Дисертації: "Estuaries Australia"

1

Chuwen, Benjamin Michael. "Characteristics of the ichthyofaunas of offshore waters in different types of estuary in Western Australia, including the biology of black bream Acanthopagrus butcheri /." Murdoch University Digital Theses Program, 2009. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20100210.154423.

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2

Deeley, D. M. "Evaluating indicators of ecological health for estuaries in southwest Australia." Thesis, Deeley, D.M. (2001) Evaluating indicators of ecological health for estuaries in southwest Australia. PhD thesis, Murdoch University, 2001. https://researchrepository.murdoch.edu.au/id/eprint/3371/.

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A broad range of environmental indicators were evaluated to determine their suitability for describing the early onset of nutrient enrichment in south-west Australian estuaries. The southwest of Australia experiences a Mediterranean climate with hot dry summers and cool wet winters. Most of the south-west estuarine catchments have been extensively cleared for agricultural and urban development and have been loosing unacceptably high loads of nutrients. Symptoms of nutrient enrichment have been observed in many south-west estuaries. An evaluation of fifty years of historical water quality data defined the range of normal behaviour for these systems together with the nature of rarer extreme events. It was found that south-west Australian estuaries are highly variable in space and time and appear to be more susceptible to nutrient enrichment than those observed elsewhere in Australia. While there may be significant fluctuations in physico-chemical conditions and the structure of biological communities in ecosystems subjected to natural variability and anthropogenic stressors, it is possible that the junction of biological communities in these situations is less affected by these types of perturbations. Several indicators of biological function (rates and processes) were developed and evaluated to determine whether they offered a greater degree of diagnostic precision (early warning) than measures of stocks and status (inventory). In evaluating various environmental indicators, it was found that no single indicator was able to unambiguously define the interactions between physic-chemical and biological processes and the response of these systems to anthropogenic and natural stressors. It has been concluded that a broad range of potential indicators must be evaluated simultaneously, in order to define baseline conditions, measurement endpoints and trends to inform catchment and estuarine management and restoration. Increased confidence in the selected indicator suite can flow from an evaluation of the monotonicity of correlated indicators, especially when assessments show consistent patterns for physico-chemical measures and measures of biotic community structure across several trophic groups. Traditional physic-chemical indicators have provided reliable information in me past, but problems have arisen when relating these measures to biological endpoints, particularly for estuaries with significant seasonal and inter-annual variability. In the absence of biological data for estuarine ecosystems experiencing significant seasonal and inter-annual variability, socio--economic indicators of catchment land use practices may be the only option. Paleolimnological investigations may also provide additional insight into patterns of natural variability over the longer term, but the degree of taxonomic resolution required and requirements for supporting stable isotope analysis, may consume considerable resources. Autotrophic protistans (periphyton, phytoplankton), appear to be useful for describing nutrient enrichment, salinity and other physico-chemical conditions, but complicating factors such as the nature of coupling of secondary predation need to be identified. Autecology of local indicator species also needs to be defined. Zooplankton appear to be limited as environmental indicators, but because of their potential role in grazing and materials transfer, they may be useful as elements of biotic indices across several trophic groups. One of the major impediments to using planktonic organisms for inferring the condition of estuarine health is the considerable vertical, horizontal and temporal heterogeneity displayed by these organisms in both disturbed and undisturbed systems. More recently, benthic macro-invertebrates have been successfully used to describe the nature and magnitude of organic enrichment of estuaries. Community structure, biomass and relative abundance of functional groups and indicator species have also been developed and used as environmental indicators. Problems may occur in the use of these organisms to infer health in south-west estuaries because of the presence of naturally immature communities and variable colonization dynamics where there is significant seasonal and inter-annual variability. Inventory measures of community structure have problems because of a lack of information about exchange pathways connecting system components and unknown interactions between diversity, stability and resilience of the ecosystem. Species richness, diversity indices and measures of biomass have probably been the most widely used indicators in the majority of published works, but generally without appropriate critical analysis of their utility. Biomass appears to have less inter-annual variability than do other measures of community structure. A myriad of biotic indices (ratios of functional groups) within and across trophic levels have been described in the international literature. There are problems in defining weightings and concordance methods for elements contributing to biotic indices and the loss of valuable information during these types of data reduction limit their potential. Detailed autecology of members of functional groups are required for biotic indices and this type of information is potentially available for some cosmopolitan species, but generally lacking for endemic species which may describe important nuances of the local environment. As with biotic indices, there is a range of combined metrics described in the literature. Metrics generally combine physico-chemical elements, and may include some biological information. Many of the problems with biotic indices apply equally to metrics, but when calibrated for a particular local situation, they offer considerable discriminatory power. Assessment of early colonisation dynamics and the responsiveness of periphyton communities to nutrient additions provided insights into some key processes in south-west estuaries. Periphyton communities in estuaries with a past history of nutrient enrichment responded well to nutrient additions while communities in less disturbed estuaries did not respond as readily. This infers that opportunistic species able to respond rapidly to nutrient additions may become established in estuaries having a nutrient enrichment history while they may be less able to maintain a viable presence in less enriched estuaries. While showing promise, additional testing and refinement of these process indicators would better define their potential as early warning indicators of nutrient enrichment for south-west estuaries. For describing the ecological health of south-west Australian estuaries, physico-chemical indicators of catchment and estuarine water quality and socio-economic measures of catchment land use history may be of use. If assumptions about the linearity of interactions between the diversity of biotic communities and the stability and resilience of ecosystem function are valid, then conventional measures of community structure will also provide useful insights. The ongoing selection, evaluation and refinement of environmental indicators for assessing the ecological health of south-west Australian estuaries, needs to proceed as a close partnership between land and waterway managers and scientific specialists.

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Mazumder, Debashish, and res cand@acu edu au. "Contribution of Saltmarsh to Temperate Estuarine Fish in Southeast Australia." Australian Catholic University. School of Arts and Science (NSW, 2004. http://dlibrary.acu.edu.au/digitaltheses/public/adt-acuvp47.09042006.

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Saltmarsh is an important coastal habitat located in the littoral zone of estuaries. Australian saltmarsh area is decreasing due to agricultural and urban development and invasion by mangrove. The aim of the study was to assess the contribution made by saltmarsh as a habitat and a source of food items for fish. Three saltmarsh sites were studied, with Towra Point chosen as a site for detailed ecological study. When corrected for water volume, fish densities were found to be higher within the saltmarsh compared to the adjacent mangrove. Although the fish assemblages in saltmarshes differed significantly from mangroves the overall ratio between commercially and ecologically valuable species in these habitats are similar, a result suggesting the importance of temperate saltmarsh as habitat for economically important fish. Significant export of crab larva from saltmarsh (average crab larval abundance 2124.63 m-3 outgoing water) is a positive contribution to the estuarine food chain supplementing the nutritional requirements of estuarine fish. While the diet of the crabs producing this larvae seems dependant on the saltmarsh environment (given the contrasting isotopic signatures of Sesarma erythrodactyla in saltmarsh and mangrove, and the similarity of isotopic signatures in the saltmarsh for Sesarma erythrodactyla and Helograpsus haswellianus), the crabs do not seem to be dependent on any of the common species of saltmarsh plant, but rather depend on particulate organic matter (POM) derived from local and other sources. Crab larva are a prey item for many estuarine fish, including commercially important species, as evidenced by gut content analysis of fish visiting the saltmarsh flats during spring tides. The results strongly suggest that emphasis be given to ecosystembased management for an estuary rather than component (e.g., vegetation) based managed as defined by the Fisheries Management Act (1994) and the State Environmental Planning Policy 14.

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4

Krispyn, Kurt N. "The fish faunas of estuaries in the Albany region of south-western Australia." Thesis, Krispyn, Kurt N. (2021) The fish faunas of estuaries in the Albany region of south-western Australia. Honours thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/65015/.

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Estuaries are amongst the most productive ecosystems and act as important nurseries and habitats for aquatic fauna. Microtidal estuaries (tidal range <2 m) are particularly prone to climate change, the effects of which on fish communities and future predictions on their state under climate change are not well understood, especially for small estuaries (<1 km2). This study quantitatively determined the fish fauna in the nearshore and offshore waters of eight microtidal estuaries (including six <1 km2) with varying extents of connectivity to the ocean in the Albany region of south-western Australia. It investigated whether fish faunas were influenced by region, season, “bar status” (i.e., open or closed), and physico-chemical variables. Nearshore waters (<1.5 m) were sampled with four replicate 21.5 m seine nets in each region (lower, basin and upper) in each estuary over four seasons in 2020. Offshore waters (>1.5 m) were sampled using four 160 m composite gill nets set throughout each estuary in the same four seasons. Conductivity and temperature loggers were used to detect any breaches of the sand bar that occurred between sampling occasions. Fish faunas in nearshore and offshore waters were m different among estuaries, and across seasons and regions in shallower waters, although all estuaries were dominated by the same suite of core species. Diversity and faunal composition were highly influenced by salinity and the duration of ocean connectivity. Diversity increased with salinity due to the immigration of marine species up until hypersaline conditions (>50) occurred, however, when salinities exceeded 100 for a protracted period, only a single highly euryhaline estuarine species survived. Permanently-open estuaries, i.e., Oyster Harbour and Waychinicup Estuary, contained the greatest number of species, but lower densities (nearshore) and catch rates (offshore) than those estuaries that open at least once a year, i.e., Torbay, Taylor, Normans and Cheyne inlets and Cordinup River. The normally-closed and extremely hypersaline Beaufort Inlet was depauperate and, after autumn, no fish were recorded in offshore waters with only a single atherinid species occurring in nearshore waters. This study provides baseline information for these data-poor estuaries and identified one system of high conservation significance. It also provides insights on how estuaries and their fish fauna may change due to reduced rainfall and river flow associated with climate change, and become more like Beaufort Inlet.

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5

Loneragan, Neil Randell. "The populations and community structures of fishes in two large estuaries of south-western Australia." Thesis, Loneragan, Neil Randell (1989) The populations and community structures of fishes in two large estuaries of south-western Australia. PhD thesis, Murdoch University, 1989. https://researchrepository.murdoch.edu.au/id/eprint/11723/.

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The fish fauna of the large and adjacent Swan and Peel-Harvey estuaries in temperate south-western Australia, were sampled at regular intervals using beach seines, gill nets and otter trawls at a number of sites throughout these systems. A total of 673 037 individuals, representing 38 families and 76 species were caught in the Swan Estuary compared with 144 372 individuals, 29 families and 55 species in the PeelHarvey Estuary. Although the Clupeidae, Terapontidae, Mugilidae, Apogonidae and Atherinidae were the most abundant families in each system, the important species within the families differed between the estuaries. Of the 15 most abundant species in the shallows of the Swan Estuary, seven were marine teleosts which entered the estuary regularly and in large numbers (marine estuarine-opportunists), seven completed their life cycle within the estuary (estuarine) and one (Nematalosa vlaminghi) was anadromous. The contribution of individuals of the marine estuarine-opportunist category to catches in the shallows declined from nearly 95% in the lower estuary, to approximately 17% in the middle estuary and 6% in the upper estuary. The estuarine and anadromous groups together comprised 83 and 94% of the catches in the middle and upper estuaries, respectively. By contrast, marine estuarine-opportunists were the most abundant group in all regions of the Peel-Harvey, including the saline reaches of tributary rivers. The number of species and density of fish in the shallows of the Swan and PeelHarvey systems declined with distance from estuary mouth and rose with increasing salinity and temperature. Classification and ordination of the data from the shallows of both estuarine systems distinguished the ichthyofauna of the saline reaches of the rivers from that of the lower reaches of the estuary. However, the faunal composition of the middle estuary of the Swan was also relatively distinct from those of the lower and upper estuary. The number of species and catch rates in the deeper waters of the Peel-Harvey were influenced to a greater extent by salinity, than those in the shallows. This implies that the larger fish which characterise the deeper waters may thus be less tolerant to low salinities than the smaller fish, typically found in the shallows. Site within the Swan Estuary generally influenced the densities of individual species to a greater extent than either season or year, or the interactions between these factors. When seasonal effects were pronounced, they could be related to summer spawning migrations into the upper estuary (N. vlaminghi, Amniataba caudavittatus ), spring immigrations into the lower estuary (Mugil cephalus ) or winter movements into deeper and more saline waters (Apogon rueppellii ). Marked annual variations in the density of Torquigener pleurogramma were related to large differences in the recruitment of the 0+ age class between years.

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6

Qu, Wenchuan. "Studies on nitrogen cycling processes in Lake Illawarra, New South Wales, Australia." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050302.161641/index.html.

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7

Wilton, Kylee Margaret, and res cand@acu edu au. "Coastal Wetland Habitat Dynamics in Selected New South Wales Estuaries." Australian Catholic University. School of Arts and Sciences, 2002. http://dlibrary.acu.edu.au/digitaltheses/public/adt-acuvp29.29082005.

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Intertidal wetland habitats in southeastern Australia have changed significantly during the past sixty years. Mangrove habitats have expanded both seawards and landwards, the latter being at the expense of saltmarsh habitats. This relatively common phenomenon is generally suggested to be an outcome of sea-level rise. Several factors potentially responsible for this change are examined, including changes in mean sealevel during the past 50 to 100 years, changes in climate, population growth, catchment landuse, and estuary type. A protocol for mapping estuarine habitats was developed and implemented, incorporating the application of geographic information systems. Spatial and temporal coastal wetland habitat changes at nine sites along the New South Wales coast are illustrated. These habitat dynamics were shown to not correlate between sites. The results demonstrate that sea-level rise in this region cannot solely account for the extent of change during the past sixty years. With the exception of one site (Careel Bay), there have been no correlations between contemporary mean sea-level rise and mangrove incursion of the saltmarsh habitats at the study sites, or with rainfall patterns, at the scale of observation in this study, which was largely decadal. The only correlations determined during this study have been between population growth and coastal wetland habitat dynamics in some sites. In spite of saltmarsh habitat loss being a regional phenomenon, local factors appear to have a profound bearing on the rates of change. Neither contemporary mean sea-level rise, rainfall patterns, estuary type, catchment landuse, catchment natural cover nor population pressure can account solely for the patterns in the spatial and temporal dynamics of the coastal wetlands of New South Wales. It seems apparent that regional factors create preconditions favourable for mangrove incursion, but that localised conditions have been responsible for the extent of these incursions from site to site. That is, despite higher sea-level and greater rainfall, the extent of change has been determined by the unique characteristics of each site. The results have important implications for current estuary management practices in the state of New South Wales. The lack of spatial and temporal trends in coastal wetland habitat dynamics point to the need for management to be conducted on a localised, rather than regional scale. Additionally, anthropogenic influences must be carefully managed, since the extent of mangrove habitat expansion into saltmarsh areas is unlikely to be a natural occurrence.

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8

Sloss, Craig R. "Holocene sea-level change and the aminostratigraphy of wave-dominated barriers estuaries on the southeast coast of Australia." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060306.154507/index.html.

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9

Rose, Thomas H. "Comparisons of the benthic and zooplankton communities in the eutrophic Peel-Harvey and nearby Swan estuaries in south-western Australia." Thesis, Rose, Thomas H. (1994) Comparisons of the benthic and zooplankton communities in the eutrophic Peel-Harvey and nearby Swan estuaries in south-western Australia. PhD thesis, Murdoch University, 1994. https://researchrepository.murdoch.edu.au/id/eprint/51981/.

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The benthic macroinvertebrates and the zooplankton of the shallow (<1.5 m deep) sandy middle regions of the Peel-Harvey Estuary and of the nearby Swan Estuary were sampled seasonally between the winters of 1986 and 1987. Measurements were also taken of the environmental variables in the benthos and in the water column. In comparison with the Swan Estuary, the Peel-Harvey Estuary is highly nutrient enriched and is not as well flushed. As a consequence, the water in the basins of the Peel-Harvey experience large seasonal blooms of the blue-green alga Nodularia spumigena and massive growths of benthic and drifting green algae. The first led to marked seasonal declines in redox values, secchi depths and nocturnal dissolved oxygen and, together with the decomposition of the macroalgae, resulted in a marked increase in particulate organic matter in the sediments. The following comparisons between the benthic invertebrate fauna in the Peel- Harvey with that of the Swan Estuary are consistent with the effects of far greater eutrophication in the former system. (1) The number of individuals was far higher in the Peel-Harvey, whereas the number of species, diversity and biomass was greater in the Swan. (2) The contributions made by small and highly fecund polychaetes (e.g. Capitclla capitata), amphipods (e.g. Corophium minor), tanaids (e.g. Tanais dulongi) and microbivalves (e.g. Arthritica semen) to the numbers and biomass of individuals were much greater in the Peel-Harvey, whereas the contributions by large long-living bivalve molluscs and polychaetes to the numbers and more particularly the biomass of individuals were greater in the Swan. (3) While the densities and biomass of the main components of the benthic community rose to reach a maximum in spring or summer in the Swan Estuary, they peaked in autumn in the Peel-Harvey. The later peak in the latter system is apparently related to deleterious conditions present during spring and early summer, e.g. frequent episodes of hypoxia. Greater variability in the density and biomass of organisms at sites in the Peel-Harvey are assumed to reflect variation in the intensity of deleterious conditions produced by eutrophication within this system. The following comparisons also indicate that the zooplankton community of the Peel-Harvey Estuary manifests the effects of eutrophication to a greater extent than that of the Swan Estuary. (1) The abundance of individuals in the Peel-Harvey was higher than in the Swan whereas the reverse situation pertained with the number of species. (2) The density of calanoids and harpacticoids was far lower in the Peel- Harvey, presumably reflecting the influence of anoxia on their benthic stages. (3) The numbers of amphipods and nematodes were greater in the Peel-Harvey. (4) As with the benthos, the density and biomass of zooplankton varied more between sites in the Peel- Harvey and the density of the main components of the zooplankton peaked later, ie. after the deleterious conditions produced during spring and summer had amehorated. There were also a much higher number of interactions between season and time of day in the density and biomass of the zooplankton and this was attributed to the combination of eutrophication-induced hypoxia and turbidity, which altered migration patterns in comparison to the Swan. The above comparisons thus indicate that there have probably been major changes in the faunal composition of the Peel-Harvey Estuary following eutrophication and particularly the advent of Nodularia blooms since the late 1970s. This view is supported by the fact that, in comparison with the situation during the 1970s and early 1980s, the densities of gastropods in the benthos and of calanoids in the plankton are lower, while the densities of amphipods in both the benthos and zooplankton are greater.

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au, rhoddell@central murdoch edu, and Richard James Hoddell. "A mtDNA study of aspects of the recent evolutionary history and phylogeographic structure of selected teleosts in coastal environments of south-western Australia." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070831.162328.

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At present, there is a general lack of information regarding the spatial genetic architecture and genetic diversity of estuarine and coastal freshwater fish in Australia or about the interacting intrinsic, extrinsic and historical influences responsible for sculpting these patterns. This thesis represented the first investigation of the phylogeographic structure and recent evolutionary histories of teleost fishes from the coastal and estuarine environments of south-western Australia, using the resolution afforded by mtDNA sequence data. Available evidence indicated that, to different degrees, these species have limited potential for dispersal amongst local assemblages from different water bodies. As this theoretically reduces the confounding effects of recent gene flow on extant genetic structure, these fishes were well suited to studying the influences of historical factors. Historical influences were expected to be particularly profound, given that these coastal environments underwent massive modifications during Late Quaternary eustatic fluctuations. The thesis consists of four major components, which explored different aspects of interspecific and intraspecific phylogeny and p hylogeograp hy of three teleost species, based on mtDNA control region and cytochrome b fragments. First, the relationship between the endemic, 'strictly estuarine' Leptatherina wallacei (Atherinidae) and the more widespread, 'estuarine & marine' 6. presbyteroides was examined, with a view to establishing whether 6. wallacei represents a monophyletic or polyphyletic lineage and whether this species was derived recently (i.e. in Holocene estuaries). Second, the phylogeographic structure and genetic diversity of L. wallacei were investigated and compared with data from L. presbyteroides, with a view to using this information to interpret the recent evolutionary histories of each congener. Third, the divergence between assemblages of L. wallacei inhabiting two isolated coastal lakes was used to estimate a maximal substitution rate for the control region, which was then used to infer general time frames for the divergence between the two Leptatherina species and between the major phylogeographic partitions within each species. Fourth, investigations were initiated into phylogeographic patterns and levels of genetic diversity within and among assemblages of Pseudogobius olorum (Gobiidae) from several coastal lakes and an estuary. Phylogenetic analyses indicated that the two Leptatherina species were characterised by exclusive and reciprocally-monophyletic lineages of haplotypes from both mtDNA regions, supporting the monophyletic origins of L. wallacei. Both 6. wallacei and 6. presbyteroides exhibited high levels of genetic diversity and extensive overall subdivision (e.g. Qsr = 0.691 & 0.644 respectively for control region data). There was a profound phylogeographic break in both species between all conspecific assemblages from the lower west coast (LWC phylogroup) and all those from the south coast (SC phylogroup), which suggested the influences of shared extrinsic and/or historical factors. There was limited genetic structuring within the two major phylogroups of either Leptatherina species, apparently reflecting recent connectivity amongst local assemblages, with subsequent fragmentation and insufficient time for lineage sorting. However, two major phylogeographic breaks distinguished monophyletic control region phylogroups of L. wallacei from the isolated coastal Lake Clifton and Lake Walyungup, consistent with their independent evolution following lacustrine entrapment during the Holocene. The divergence between these two isolated lacustrine assemblages of Leptatherina wallaceiformed the basis for an estimate of the maximal substitution rate of the control region. While these data were unable to provide a precise estimate of the actual rate of molecular evolution, all the evidence suggested that it was proceeding very rapidly. The maximal rate estimate of 172.3% lineage-' MY-' was among the fastest ever reported. Based on this rate, the two Leptatherina species diverged at least 1 SKya, thus rejecting a Holocene origin for L. wallacei. The divergence between the LWC and SC phylogroups of L. wallacei has been ongoing for at least GKya, while the equivalent divergence in L. presbyteroides has been ongoing for at least 11 Kya. As the time frames of these divergences were consistent with periods of massive environmental modifications associated with the end-Pleistocene fall in sea level and the HMT, it was likely that these factors have played important roles in sculpting the species' divergence and intra-specific genetic structure. Although useful in temporally scaling genetic divergences within and between the two Leptatherina species, wider application of this rate estimate to questions regarding other taxa was limited. For example, evident rate heterogeneity between the genera precluded its use with even the relatively closely-related atherinid Atherinosoma elongafa. Phylogeographic analyses identified high levels of genetic diversity and extensive genetic subdivision (e.g. st = 0.652 for control region) amongst an estuarine and several lacustrine assemblages of Pseudogobius olorum, although phylogeographic structure was shallower than in either Leptatherina species. There was increased divergence between three assemblages from the lower west coast and two from the south coast, consistent with the profound break evident in the Leptatherina. One lacustrine assemblage appeared to represent a distinct lineage and a preliminary maximal rate estimate (~61.4% lineage-1 MY-1) was calculated based on the minimum divergence of this assemblage from its nearest conspecifics. Although slower than the rate calculated for L. wallacei, this was still high for teleost fishes. Overall, this study indicated that historical environmental factors, especially those related to Quaternary eustatic changes, have played important roles in sculpting the phylogeography and evolution of three teleost species from south-western Australia. Moreover, as these species have differential dependencies on estuarine environments (is. 'strictly estuarine' vs 'estuarine & marine') and represented two different taxonomic groups (i.e. Atherinoidei & Gobioidei), historical environmental factors may have exerted similar influences on other coastal species in the region.

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O'Callaghan, Joanne M. "Tidal and sediment dynamics of a partially mixed, micro-tidal estuary." University of Western Australia. Centre for Water Research, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0088.

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[Truncated abstract] The expansion of human populations in coastal land margins has resulted in major modifcations to estuarine ecosystems. The use of numerical models as predictive tools for assessing remediation strategies is increasing. However, parameterisation of physical processes, developed mainly through field investigations, is necessary for these models to be reliable and effective management tools. The physical processes in micro–tidal diurnal tidal systems are relatively unknown and the current study examines field measurements obtained from the upper Swan River estuary (Western Australia), a diurnal, partially mixed system during the summer when the freshwater discharge is negligible. The aims of the study were to characterise, temporally and spatially, the dominant physical processes and associated sediment resuspension. Variability at three dominant time-scales were examined: 1) sub–tidal oscillations (∼5 to 10 days) resulting from local and remote forcing; 2) tidal (∼ 24 hours) due to astronomical forcing; and 3) intra-tidal (∼2 to 3 hours) resulting from the interaction between tidal constituents. Circulation in estuaries is widely accepted in the literature to be dominated, in varying proportions, by tidal range, freshwater discharge and gravitational circulation. In the upper Swan River estuary sub–tidal oscillations were responsible for the largest upstream displacement of the salt wedge in the absence of freshwater discharge. Moreover, these sub–tidal fluctuations in water level modified the ‘classic’ estuarine circulation. The dynamics of diurnal tides are largely controlled by the tropic month, which oscillates at a slightly different period to the lunar month, resulting in the spring–neap tidal cycle to be sometimes different from syzygy. The phase lag between the diurnal (O1 + K1) and semi-diurnal (M2 + S2) constituents, at the seasonal time scale cause the maximum tidal range to be near the solstice. Over a 24–hour tidal cycle this phase lag is manifested as an intra–tidal oscillation that occurs on the flood tide. Turbidity events that last ∼1 to 2 hours occur during the intra–tidal oscillation, but are not related to maximum shear stress predicted from the mean flow characteristics. The increases in turbidity during the intra–tidal oscillation is, however, correlated with the near–bed Reynolds fluxes. During the intra–tidal oscillation advection opposes the estuarine circulation in the near–bed region, promoting vertical shear that results in destratifcation of the water column. The turbulent mixing generated at the interface and in the near–bed region coincide with resuspension events. Similar turbidity data have often been disregarded and documented as being ‘spikes’ based on the premise that the mean flow was below a critical level to resuspend sediment. Resuspension events were not simply related to mean processes and may be controlled by turbulent instabilities generated when tidal currents reverse during an intra-tidal oscillation

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Sarre, Gavin Ayrton. "Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia." Thesis, Sarre, Gavin Ayrton (1999) Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia. PhD thesis, Murdoch University, 1999. https://researchrepository.murdoch.edu.au/id/eprint/290/.

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The aims of the studies undertaken for this thesis on the black bream Acanthopagrus butcheri, a species which is confined to estuaries, were to determine the following. (1) The age compositions, growth rates, reproductive biology and diets of the populations of this species in four different estuaries (Swan River, Moore River, NomaluplWalpole and Wellstead estuaries) and a landlocked saline lake (Lake Clifton) and (2) the seasonal and regional distributions of this species within one estuary (Swan River Estuary). Acanthopagrus butcheri were collected at regular intervals from nearshore, shallow (> 2 m) and offshore, deeper (< 2.5 m) waters of the permanently open Swan River Estuary and intermittently open Moore River Estuary on the lower west coast of Australia and from the permanently open Nomalup/Walpole Estuary and normally closed Wellstead Estuary on the southern coast of Western Australia. One hundred A. butcheri were also obtained from a landlocked, coastal saline lake (Lake Clifton), 90 km south of the Swan River Estuary. Sampling employed seine nets, composite gill nets and rod and line. In the Swan River Estuary, black bream typically occur in the saline reaches of the tributary rivers which constitute the upper estuary. However, during heavy freshwater discharge in winter, many individuals are swept downstream into the basins that constitute the middle estuary. These fish migrate back into the upper estuary in spring and the larger fish spawn in this region between the middle of spring and early summer. Although smaller fish tend to remain in the upper estuary during summer as salinities increase, the larger fish migrate further upstream where salinities are lower. The salinities in which A.butcheri spawned in the different systems ranged from as low as 5.5 - 6.8 %CJin the Moore River Estuary to as high as 40.7 - 45.2 %O in the Wellstead Estuary. The use of marginal increment analyses demonstrated that the opaque zones revealed in otoliths by sectioning are formed annually and could thus be used for ageing individual fish and that the opaque zones visible in whole otoliths prior to sectioning could be used for ageing fish up to six years old. The number of annuli on scales did not provide a reliable estimate of age. The structure of the age compositions in the four estuaries varied, presumably reflecting differences in fishing pressure and, in one case, the lack of recruitment in some years. The growth rates of A. butcheri in the four estuaries and landlocked lake differed, which is probably related to variations in one or more of the following; water temperature, density of fish, salinity and the type of food available. The monthly trends exhibited by gonadosomatic indices and the prevalence of different gonadal maturity stages and mature oocytes demonstrate that spawning typically occurs in spring and early summer. The frequent occurrence of yolk vesicle, yolk granule oocytes and post-ovulatory follicles in the ovaries of some mature fish provides strong circumstantial evidence that A. butcheri is a multiple spawner, i.e. spawns more than once during each breeding season. Estimates of the minimum total fecundity ranged between 9.07 x lo4 and 7.09 x lo6, with a mean of 1.58 x lo6. Variations amongst the lengths and ages at first maturity in three of the estuarine populations of A. butcheri could apparently be attributed to the influence of variations in growth rate. Female and male Acanthopagrus butcheri both possess an ovotestis, a feature characteristic of the Sparidae. There is strong circumstantial evidence that, once a member of this species reaches maturity, it can be considered a rudimentary hermaphrodite, i.e. it possesses either functional ovaries and far smaller and immature testes or functional testes and immature ovaries of variable size. There was no evidence that this species undergoes either a protogynous or protandrous sex change. Acanthopagrus butcheri can consume various benthic and epibenthic prey, including crustaceans, polychaetes, molluscs and teleosts, and can also ingest considerable volumes of algae. However, the dietary compositions of A. butcheri in the four estuaries and Lake Clifton differed markedly, whch, together with information on the biota in those systems, indicate that A. butcheri feeds on those prey items that are most abundant in their environment. Yet, there is also evidence that, in any given system, A. butcheri will focus on a particular prey, even when other prey, which are regularly consumed in considerable volume in other systems, are abundant. The dietary compositions of A. butcheri in each estuary underwent ontogenetic changes, which would reduce the potential for intraspecific competition for food resources.

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13

Sarre, Gavin Ayrton. "Age compositions, growth rates, reproductive biology, and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia." Connect to this title online, 1999. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060818.135836.

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14

Sarre, G. A. "Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia." Murdoch University, 1999. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060818.135836.

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Анотація:

The aims of the studies undertaken for this thesis on the black bream Acanthopagrus butcheri, a species which is confined to estuaries, were to determine the following. (1) The age compositions, growth rates, reproductive biology and diets of the populations of this species in four different estuaries (Swan River, Moore River, NomaluplWalpole and Wellstead estuaries) and a landlocked saline lake (Lake Clifton) and (2) the seasonal and regional distributions of this species within one estuary (Swan River Estuary). Acanthopagrus butcheri were collected at regular intervals from nearshore, shallow (< 2 m) and offshore, deeper (> 2.5 m) waters of the permanently open Swan River Estuary and intermittently open Moore River Estuary on the lower west coast of Australia and from the permanently open Nomalup/Walpole Estuary and normally closed Wellstead Estuary on the southern coast of Western Australia. One hundred A. butcheri were also obtained from a landlocked, coastal saline lake (Lake Clifton), 90 km south of the Swan River Estuary. Sampling employed seine nets, composite gill nets and rod and line. In the Swan River Estuary, black bream typically occur in the saline reaches of the tributary rivers which constitute the upper estuary. However, during heavy freshwater discharge in winter, many individuals are swept downstream into the basins that constitute the middle estuary. These fish migrate back into the upper estuary in spring and the larger fish spawn in this region between the middle of spring and early summer. Although smaller fish tend to remain in the upper estuary during summer as salinities increase, the larger fish migrate further upstream where salinities are lower. The salinities in which A. butcheri spawned in the different systems ranged from as low as 5.5 - 6.8 %CJin the Moore River Estuary to as high as 40.7 - 45.2 %O in the Wellstead Estuary. The use of marginal increment analyses demonstrated that the opaque zones revealed in otoliths by sectioning are formed annually and could thus be used for ageing individual fish and that the opaque zones visible in whole otoliths prior to sectioning could be used for ageing fish up to six years old. The number of annuli on scales did not provide a reliable estimate of age. The structure of the age compositions in the four estuaries varied, presumably reflecting differences in fishing pressure and, in one case, the lack of recruitment in some years. The growth rates of A. butcheri in the four estuaries and landlocked lake differed, which is probably related to variations in one or more of the following; water temperature, density of fish, salinity and the type of food available. The monthly trends exhibited by gonadosomatic indices and the prevalence of different gonadal maturity stages and mature oocytes demonstrate that spawning typically occurs in spring and early summer. The frequent occurrence of yolk vesicle, yolk granule oocytes and post-ovulatory follicles in the ovaries of some mature fish provides strong circumstantial evidence that A. butcheri is a multiple spawner, i.e. spawns more than once during each breeding season. Estimates of the minimum total fecundity ranged between 9.07 x lo4 and 7.09 x lo6, with a mean of 1.58 x lo6. Variations amongst the lengths and ages at first maturity in three of the estuarine populations of A. butcheri could apparently be attributed to the influence of variations in growth rate. Female and male Acanthopagrus butcheri both possess an ovotestis, a feature characteristic of the Sparidae. There is strong circumstantial evidence that, once a member of this species reaches maturity, it can be considered a rudimentary hermaphrodite, i.e. it possesses either functional ovaries and far smaller and immature testes or functional testes and immature ovaries of variable size. There was no evidence that this species undergoes either a protogynous or protandrous sex change. Acanthopagrus butcheri can consume various benthic and epibenthic prey, including crustaceans, polychaetes, molluscs and teleosts, and can also ingest considerable volumes of algae. However, the dietary compositions of A. butcheri in the four estuaries and Lake Clifton differed markedly, whch, together with information on the biota in those systems, indicate that A. butcheri feeds on those prey items that are most abundant in their environment. Yet, there is also evidence that, in any given system, A. butcheri will focus on a particular prey, even when other prey, which are regularly consumed in considerable volume in other systems, are abundant. The dietary compositions of A. butcheri in each estuary underwent ontogenetic changes, which would reduce the potential for intraspecific competition for food resources.

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15

Coen, Natasha. "Implications of habitat type on the hyperbenthos of two morphologically divergent estuaries, and their adjacent nearshore marine waters, along the lower west coast of Australia." Thesis, Coen, Natasha (2016) Implications of habitat type on the hyperbenthos of two morphologically divergent estuaries, and their adjacent nearshore marine waters, along the lower west coast of Australia. PhD thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/32297/.

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This study characterised the nearshore habitats and hyperbenthic fauna of two permanently-open but morphologically divergent estuaries along Australia’s lower west coast (the Swan-Canning and Peel-Harvey). The overarching aim was to assess whether spatial differences in the environmental characteristics of habitats could be used as a reliable basis for predicting those in faunal composition. The hyperbenthos of these temperate microtidal estuaries were also compared to that in the nearby coastal waters, and used to test several paradigms about faunal differences between estuarine and marine environments. This is the first hyperbenthic study in any Australian estuary. A quantitative approach was developed for classifying local-scale estuarine habitats using environmental criteria that were ecologically-relevant, readily available and enduring. It was applied to the above estuaries then expanded to account for geographical region and estuarine bar state and applied to two other south-western Australian systems, the seasonally-open Wilson Inlet and normally-closed Wellstead Estuary. Sampling of the hyperbenthos at various habitats throughout the Swan-Canning and Peel-Harvey estuaries in winter 2005 and summer 2006 yielded 72-92 species, 10-12 phyla (mainly Crustacea) and 5,602-9,347 individuals in each system. Mean species richness, density, diversity and composition differed significantly among habitats in each estuary and season, although not always between all habitats. Habitat differences in the hyperbenthos were almost always significantly correlated with those in the environmental attributes, indicating that the classification scheme provides a reliable basis for predicting these fauna at any unsampled site in these estuaries. Comparisons of the hyperbenthos between the above estuaries and that in the adjacent coastal waters showed that both the mean number of species and density were far greater in the marine than estuarine environments, while mean diversity was similar in all systems except the Peel-Harvey in summer, where it was significantly lower. The trends in species richness support widely-accepted paradigms of faunal differences between estuarine and marine waters, those in diversity provide partial support, while those in density are in profound opposition. Species composition differed extensively between the estuarine and marine waters, and also differed between the two estuaries but to a far lesser extent. As the first study of the hyperbenthos in Australian estuaries, and to compare these assemblages with those in adjacent marine environments, this thesis provides extremely valuable insight into these fauna and builds on the relatively limited knowledge of hyperbenthos in the southern hemisphere.

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16

Sarre, Gavin A. "Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia." Sarre, Gavin A. (1999) Age compositions, growth rates, reproductive biology and diets of the black bream Acanthopagrus butcheri in four estuaries and a coastal saline lake in south-western Australia. PhD thesis, Murdoch University, 1999. http://researchrepository.murdoch.edu.au/290/.

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Анотація:

The aims of the studies undertaken for this thesis on the black bream Acanthopagrus butcheri, a species which is confined to estuaries, were to determine the following. (1) The age compositions, growth rates, reproductive biology and diets of the populations of this species in four different estuaries (Swan River, Moore River, NomaluplWalpole and Wellstead estuaries) and a landlocked saline lake (Lake Clifton) and (2) the seasonal and regional distributions of this species within one estuary (Swan River Estuary). Acanthopagrus butcheri were collected at regular intervals from nearshore, shallow (> 2 m) and offshore, deeper (< 2.5 m) waters of the permanently open Swan River Estuary and intermittently open Moore River Estuary on the lower west coast of Australia and from the permanently open Nomalup/Walpole Estuary and normally closed Wellstead Estuary on the southern coast of Western Australia. One hundred A. butcheri were also obtained from a landlocked, coastal saline lake (Lake Clifton), 90 km south of the Swan River Estuary. Sampling employed seine nets, composite gill nets and rod and line. In the Swan River Estuary, black bream typically occur in the saline reaches of the tributary rivers which constitute the upper estuary. However, during heavy freshwater discharge in winter, many individuals are swept downstream into the basins that constitute the middle estuary. These fish migrate back into the upper estuary in spring and the larger fish spawn in this region between the middle of spring and early summer. Although smaller fish tend to remain in the upper estuary during summer as salinities increase, the larger fish migrate further upstream where salinities are lower. The salinities in which A.butcheri spawned in the different systems ranged from as low as 5.5 - 6.8 %CJin the Moore River Estuary to as high as 40.7 - 45.2 %O in the Wellstead Estuary. The use of marginal increment analyses demonstrated that the opaque zones revealed in otoliths by sectioning are formed annually and could thus be used for ageing individual fish and that the opaque zones visible in whole otoliths prior to sectioning could be used for ageing fish up to six years old. The number of annuli on scales did not provide a reliable estimate of age. The structure of the age compositions in the four estuaries varied, presumably reflecting differences in fishing pressure and, in one case, the lack of recruitment in some years. The growth rates of A. butcheri in the four estuaries and landlocked lake differed, which is probably related to variations in one or more of the following; water temperature, density of fish, salinity and the type of food available. The monthly trends exhibited by gonadosomatic indices and the prevalence of different gonadal maturity stages and mature oocytes demonstrate that spawning typically occurs in spring and early summer. The frequent occurrence of yolk vesicle, yolk granule oocytes and post-ovulatory follicles in the ovaries of some mature fish provides strong circumstantial evidence that A. butcheri is a multiple spawner, i.e. spawns more than once during each breeding season. Estimates of the minimum total fecundity ranged between 9.07 x lo4 and 7.09 x lo6, with a mean of 1.58 x lo6. Variations amongst the lengths and ages at first maturity in three of the estuarine populations of A. butcheri could apparently be attributed to the influence of variations in growth rate. Female and male Acanthopagrus butcheri both possess an ovotestis, a feature characteristic of the Sparidae. There is strong circumstantial evidence that, once a member of this species reaches maturity, it can be considered a rudimentary hermaphrodite, i.e. it possesses either functional ovaries and far smaller and immature testes or functional testes and immature ovaries of variable size. There was no evidence that this species undergoes either a protogynous or protandrous sex change. Acanthopagrus butcheri can consume various benthic and epibenthic prey, including crustaceans, polychaetes, molluscs and teleosts, and can also ingest considerable volumes of algae. However, the dietary compositions of A. butcheri in the four estuaries and Lake Clifton differed markedly, whch, together with information on the biota in those systems, indicate that A. butcheri feeds on those prey items that are most abundant in their environment. Yet, there is also evidence that, in any given system, A. butcheri will focus on a particular prey, even when other prey, which are regularly consumed in considerable volume in other systems, are abundant. The dietary compositions of A. butcheri in each estuary underwent ontogenetic changes, which would reduce the potential for intraspecific competition for food resources.

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17

Claus, Sonia Carmel, University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "Heavy metals in biota from temperate Australian estuaries." THESIS_CSTE_SFH_Claus_S.xml, 2003. http://handle.uws.edu.au:8081/1959.7/503.

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The detection of anthropogenic impacts in our estuaries has become a critical social, political and scientific concern in recent years. Work has focussed on the effects of these impacts on the spatial and temporal patterns of biotic assemblages and searched for bioindicators and biomarkers of pollutants that may act as early warning signs. The estuaries in temperate Southeastern Australia have a diversity of biotic assemblages living in the soft sediment. One of the most abundant macroinvertebrates is the little studies mussel, Xenostrobus securi that is found living with an assemblage of benthic biota including amphipods, crabs, isopods and tanaids, bivalves and gastropods. Two commercial fish species bream and mullet also inhabit these estuaries. Numerous stormwater drains can be found entering the estuaries through the mangrove forests lining the shores. Along with inputs of freshwater, stormwater drains are thought to be responsible for the entry of heavy metals into estuaries. These heavy metals have the potential to alter the patterns of biotic assemblages and bioaccumulate in the tissues of miacroinvertebrates, mussels and fish living within temperate estuaries. Over the time of this study the concentrations of heavy metals in the sediment tissues and shell of X.Securis varies spatially and temporally. Although this study adds substantially to current knowledge there is still more that is needed to establish X. Securis as a bioindicator. Questions remain about uptake, depuration and response to environmental gradients of heavy metals in X. Securis. Before X Securis can be used routinely in monitoring heavy metal contamination these questions need to be further investigated
Doctor of Philosophy (PhD)

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18

Claus, Sonia Carmel. "Heavy metals in biota from temperate Australian estuaries /." View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051013.092820/index.html.

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Thesis (Ph.D.) -- University of Western Sydney, 2003.
"Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.

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19

Mazumder, Debashish. "Contribution of saltmarsh to temperate estuarine fish in southeast Australia." Thesis, Australian Catholic University, 2004. https://acuresearchbank.acu.edu.au/download/6dbd534f7861bacf0f59f392d1b2ecd75f2b50b02048bebf8d84fcf60b2ca640/1902051/64981_downloaded_stream_206.pdf.

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Saltmarsh is an important coastal habitat located in the littoral zone of estuaries. Australian saltmarsh area is decreasing due to agricultural and urban development and invasion by mangrove. The aim of the study was to assess the contribution made by saltmarsh as a habitat and a source of food items for fish. Three saltmarsh sites were studied, with Towra Point chosen as a site for detailed ecological study. When corrected for water volume, fish densities were found to be higher within the saltmarsh compared to the adjacent mangrove. Although the fish assemblages in saltmarshes differed significantly from mangroves the overall ratio between commercially and ecologically valuable species in these habitats are similar, a result suggesting the importance of temperate saltmarsh as habitat for economically important fish. Significant export of crab larva from saltmarsh (average crab larval abundance 2124.63 m-3 outgoing water) is a positive contribution to the estuarine food chain supplementing the nutritional requirements of estuarine fish. While the diet of the crabs producing this larvae seems dependant on the saltmarsh environment (given the contrasting isotopic signatures of Sesarma erythrodactyla in saltmarsh and mangrove, and the similarity of isotopic signatures in the saltmarsh for Sesarma erythrodactyla and Helograpsus haswellianus), the crabs do not seem to be dependent on any of the common species of saltmarsh plant, but rather depend on particulate organic matter (POM) derived from local and other sources. Crab larva are a prey item for many estuarine fish, including commercially important species, as evidenced by gut content analysis of fish visiting the saltmarsh flats during spring tides. The results strongly suggest that emphasis be given to ecosystembased management for an estuary rather than component (e.g., vegetation) based managed as defined by the Fisheries Management Act (1994) and the State Environmental Planning Policy 14.

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20

Jelbart, Jane E., University of Western Sydney, of Science Technology and Environment College, and School of Environment and Agriculture. "The influence of seascape spatial features on the fish and macroinvertebrates in seagrass beds." THESIS_CSTE_EAG_Jelbert_J.xml, 2004. http://handle.uws.edu.au:8081/1959.7/492.

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Seagrass beds of Zostera capricorni are an integral part of the estuarine landscape along the east coast of Australia forming important habitats for juvenile fish and macroinvertebrates. Seagrass beds can vary in their spatial structural such as their size, shape and patchiness of seagrass cover. They can also be located within the estuarine landscape context such as their proximity to other habitats or their location within the estuary. The influence or correlation of these landscape or seascape spatial features of seagrass beds on the assemblages of seagrass fauna (fish and macroinvertebrates) was tested in this thesis. It was found that the spatial structure of seagrass beds (size and shape), their patchiness of the seagrass cover and location within the estuary (close or far from estuary mouth) were correlated with the assemblages of fish within seagrass beds. In particular it was demonstrated that there were greater densities of small fish species in the small compared to the large beds of Z. capricorni. This occurred regardless of the placement of the seagrass bed within the estuary context, its proximity to other habitats or patchiness of cover. Further experimentation using artificial seagrass patches demonstrated that this effect of patch size was independent of the perimeter length or perimeter to area ratio of the seagrass beds. It was hypothesised that the greater density of small fish species in small seagrass beds could be attributed to the greater proportion of edge habitats in small beds i.e. edge-mediated effects. However, the number of fish species per net haul in edges and inner regions of small and large seagrass beds were measured and found not to be different. The outcomes of this research suggest that to conserve the small fish species within an estuary, it is essential to protect even the small and patchy seagrass beds. A network of seagrass beds from all regions of the estuary is also required and the adjacent mangrove forests must be included
Doctor of Philosophy (PhD)

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21

Zharikov, Yuri. "Feeding ecology of shorebirds (Charadrii) spending the non-breeding season on an Australian subtropical estuarine flat /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16734.pdf.

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22

Rochford, Louisa. "Stormwater heavy metal loadings to Port Jackson Estuary, NSW, Australia." University of Sydney, 2008. http://hdl.handle.net/2123/4087.

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Анотація:

Master of Science
Investigations of fluvial and estuarine sediments have indicated stormwater is an important source of heavy metals to Port Jackson estuary and high concentrations of these sedimentary contaminants are a threat to the healthy functioning of the estuarine ecosystem. Stormwater remediation devices have been installed in stormwater channels entering the estuary, however these devices are mainly for removing gross pollutants and are ineffective in removing heavy metals from stormwater. A thorough characterisation of heavy metal inputs and behaviour has been undertaken by sampling, analysing and modelling heavy metals in stormwater entering Port Jackson estuary to provide a rigorous data base for future remediation efforts. A conceptual model of transport and fate of heavy metals in stormwater entering Port Jackson estuary has also been developed to identify heavy metals, subcatchments and flow regimes requiring remediation, and to assist in designing remediation devices for optimum removal of heavy metals from stormwater. Modelling of stormwater using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) indicated that the average annual discharge of stormwater from the Port Jackson catchment was 215,307 ML. Average annual loadings of arsenic, cadmium, chromium, copper, nickel, lead and zinc in stormwater discharging to Port Jackson estuary were 0.8, 0.5, 1.7, 3.2, 1.1, 3.6 and 17.7 tonnes per year, although comparison to other studies in the catchment suggests these values may be underestimations of actual loadings by 1.3 to 10 times. The proportion of heavy metals discharged under low-flow conditions (<5mm of rainfall in 24 hours), medium-flow conditions (between 5 and 50mm in 24 hours), and high-flow conditions (>50 mm of rainfall in 24 hours) was 6.5%, 62.5% and 31%, respectively. The conceptual model indicates stormwater loadings of copper, lead and zinc pose a risk to the health of riverine and estuarine ecosystems in the catchment and these metals should be targeted for remediation. Stormwater channels which should be prioritised for remediation include the channels entering southern embayments west of Darling Harbour; Duck, Parramatta and Lane Cove Rivers; and the channels and rivers entering Neutral, Long and Sugarloaf Bays. Stormwater loadings of lead are predominantly associated with suspended particulates, whereas loadings of copper and zinc are equally partitioned between dissolved and particulate phases. Stormwater remediation strategies should target both dissolved and particulate phases to ensure effective removal of copper, lead and zinc. Research suggests heavy metals in stormwater discharged to the estuary under high-flow conditions are rapidly exported seaward and bypass the estuary. Preliminary research also suggests that under medium-flow conditions, particulate heavy metals bypass the embayments of Port Jackson and are deposited in the main channel. Once deposited in the main channel, particulate heavy metals are likely to be remobilised and removed from the estuary through multiple phases of resuspension. Although further research is required in this area, this preliminary research suggests remediation should target low-flow conditions. The findings of the current research could be used to identify appropriate remediation strategies for dissolved and particulate phase heavy metals in stormwater discharging to Port Jackson estuary. However, in designing stormwater remediation devices, consideration should also be given to the range of contaminants that may be present in stormwater entering Port Jackson estuary (including suspended solids, nutrients, pesticides and organics).

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23

Pham, Cong Tri. "The ecology of fish larvae in Pumicestone Passage : an estuarine system in Southeast Queensland, Australia /." St. Lucia, Qld, 2000. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16437.pdf.

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24

Astill, Helen Lee. "The role of benthic macroalgae in sediment-water nutrient cycling in the Swan-Canning estuarine system, Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2000. https://ro.ecu.edu.au/theses/1344.

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This study documented the macroalgal assemblages of the Swan-Canning Estuarine System (SCES) over a two year period, and the influences of several environmental parameters on the assemblages. In addition, the Impacts of unattached macroalgal accumulations on benthic nutrient fluxes and microbial communities were investigated. Benthic macroalgal assemblages and physico-chemical regimes were monitored in the SCES, to determine temporal and spatial changes in macroalgal communities and the influence of environmental factors in these changes. Physico-chemical regimes demonstrated strong seasonal changes, which revolved around the onset and cessation of freshwater flows in winter (May to September). In the months after freshwater flows, strong spatial variability in physico-chemical profiles was observed. However, by summer the system was essentially marine. Macroalgal biomass and species richness was lowest in winter. Species number was maximal during periods of greatest hydrological variability in the estuary (spring and autumn). It may be inferred from results of statistical analyses that substrate type (i.e. hard/soft) and waterflow were the most Influential factors over temporal and spatial distribution of macroalgal species in the SCES. These factors ware reflected by the patchiness of macroalgal distribution in the system- attached macroalgal species distributed unevenly according to availability of limited hard substrate and presence/absence of unattached macroalgal species corresponding to seasonal freshwater flows. One species, Gracileria comosa, dominated macroalgal biomass and was the most widespread species and commonly occurred as extensive, unattached accumulations. As G. comosa was the most abundant unattached macroalga, accumulations of this species were investigated to determine the characteristics and behaviour or accumulations in the Swan-Canning Estuarine System. Accumulations were characterised by seasonally measuring height and biomass of accumulations in three regions or the estuarine system over one year. The height of accumulations was generally between 5 and 25cm, regardless of water depth, location, or season. Biomass was highly variable, but generally between 100 and 500 dw/m2 . The persistence of macroalgal accumulations was monitored at 28 sites within 10 estuarine regions, over a three month period, during which the first freshwater flows were recorded. Accumulations persisted between one week and one month, depending on the region, with accumulations persisting for longer periods in areas of low flow such as embayments and the regulated Canning River, and for shorter periods In regions of higher flow such as the channalised Swan River. Field and laboratory studies were performed to determine If the presence of G. comosa accumulations had an Impact on sediment-water nutrient exchange. Field studies established that accumulations affected benthic nutrient fluxes within a 24 hour period. However, this effect was site-dependent, occurring at an estuarine site of relatively high sediment organic content, but not at a site of relatively low sediment organic. Diurnal changes in water quality inside algal accumulations corresponded to photosynthetic/respiratory activity of the macroalgae - most notably, Increases In orthophosphate and ammonium fluxes from the sediment after approximately 8h of darkness. Since this effect was on time scales less than the period of persistence (weeks to months), It was concluded that macroalgal accumulations have an impact on benthic nutrient fluxes from sediments of relatively high organic content in the system. Laboratory studies investigated the effect of depth and density of an algal layer on sediment- water nutrient exchange. The experimental results concurred with field observations; water column concentrations of inorganic nutrients were significantly higher in sediment cores overlain by an algal layer over a 7 day period. In addition, Inorganic nutrient concentrations increased With Increasing height of the layer and ammonium concentrations increased with increasing density of the algal layer. Additional laboratory experiments tested the effect of an algal layer on sediment denitrification rates, and the composition and distribution of benthic microbial populations, Benthic nitrogen (N2) release rates were low irrespective of the presence of macroalgae and sediment types (less than 1mmo N/m2/d). However, release rates were significantly higher in sediment cores covered by algae than in comparable bare sediment cores, provided the algal layer was relatively high (5cm in height} and sediment organic content was high. The presence of an algal layer did not have a significant effect on the composition or distribution of microbes in the sediment. In all cases, microbial populations contained relatively few denitrifiers/nitrate reducers compared to nitrifiers and ammonifiers. High ammonium release rates from the sediment to the water column, and the low release rates of elemental nitrogen, suggested that even II the nitrate reducing bacteria were active they were not reducing nitrate to nitrogen, suggesting the possibility of Dissimilatory Nitrate Reduction to Ammonium (DNRA). Subsequent analysis confirmed that the nitrate reducers were reducing nitrate to nitrite, a result compatible with the hypothesis that the main microbial processes occurring were ammonification, nitrification, and DNRA, but not denitrification. These processes, regardless of the presence of a benthic algal layer, contribute to high ammonium flux rates from the sediment and provide a mechanism of internal inorganic nitrogen regeneration. In conclusion, this study has established that unattached macroalgal accumulations are a prominent component of the macroatgal community in the Swan-Canning Estuarine System. Accumulations may remain within an estuarine region for up to one month, particularly in regions of low water flow. In seasons and regions of relatively high water flows (e.g. the Swan River), accumulations become highly transient, if present at all. At times, and in regions where they may persist, algal accumulations of 5cm or more in depth have an impact on benthic nutrient fluxes. In particular, their presence over sediments of high organic content appears to exacerbate the release of ammonium from the sediment to the overlying water column. Of note, the benthic process Dissimilatory Nitrate Reduction to Ammonium appears to dominate in summer while denitrification rates are minimal, regardless of the presence of a macroagal layer. From these findings, it is recommended that high fluxes of ammonium in the system be recognised In water quality management and nutrient budgets for the system, as It appears that Internal ammonium regeneration Is a large source of Inorganic nitrogen for organisms In the overlying water body, and may support algal blooms In summer. In addition, it appears that the most appropriate method of managing macroalgal distribution and biomass in the system is ensuring strong freshwater flushes during winter periods when macroalgal biomass is largely removed. If seasonal flushes were inhibited, it is predicted that macroalgal biomass and distribution would increase, extending the period that thsy can influence benthic nutrient cycles. The physical removal of macroalgae as a management option in such a scenario would require much time and effort, as the Swan-Canning Estuarine System is such a large system, and macroalgae are spread throughout. Therefore, in modifying river flows into the estuarine system, the quantity, composition and distribution of macroalgae, and possibly other flora and fauna, will be altered. This is already evident in the Canning River, which is regulated and suffers management problems, such as altered species composition, bathymetric changes, toxic algal blooms, and eutrophication.

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25

Barnes, Peter Brendan. "Environmental impacts and the ecology of sponges and ascidians in south-eastern Australian coastal lakes and lagoons." Department of Biological Sciences - Faculty of Science, 2009. http://ro.uow.edu.au/theses/849.

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Estuaries worldwide are under threat from urbanisation and development and will need effective management for their successful conservation. Coastal lakes and lagoons have been identified as one of the estuary types most susceptible to human impacts largely because of their isolated nature and slow flushing times. Management of estuaries will be most effective when based on a sound scientific understanding of the patterns of distribution, biology and ecology over the full range of biodiversity of these systems, however, such an understanding is lacking for many systems and many taxa. Studies of sponges and ascidians in coastal lakes and lagoons are rare compared to other taxa, particularly in the southern hemisphere. This study represents the first detailed scientific investigation of the ecology of sponges and ascidian in coastal lakes and lagoons of southeastern Australia. Consequently, a large part of this thesis was devoted to quantifying basic patterns of distribution. I started with a pilot study to develop an effective sampling design, followed by large-scale comparisons among different types of lake, comparisons among habitats within lakes and an environmental impact study. I concluded with a manipulative experiment to examine processes responsible for smallscale patterns of distribution of sponges in seagrass meadows.In the pilot study, distributions of sponges and ascidians were quantified at a hierarchy of three spatial scales in each of two coastal lakes. Nested analyses of variance were then used to identify spatial scales at which variation was significant. Most sponges and ascidians were very patchily distributed at a range of spatial scales from 10s of metres up to 100s of kilometres. Unlike other published examples of cost– benefit analyses, very few taxa were widespread over the larger spatial scales. Cost– benefit analyses done to determine the optimal sampling design revealed inclusion of patchily distributed taxa in analyses improved the overall precision of sampling for comparisons of assemblages among lakes.Large-scale comparisons of assemblages of sponges and ascidians were made among lakes of different size (big versus small), opening regime (mostly open to the ocean versus mostly closed) and level of environmental modification (extensively modified versus more pristine). Similar to other taxa studied in coastal lakes, in general there were more species in lakes mostly open to the ocean compared to the mostly closed lakes, and importantly, no sponges and only one species of ascidian was found in the small closed lakes. There also appeared to be an effect of the level of modification of a lake with relatively smaller abundances of ascidians in extensively modified lakes, and a complete absence of sponges from one of the extensively modified lakes.Habitat-associated patterns were examined at smaller spatial scales by comparing the distributions of sponges and ascidians with the species composition and percentage cover of seagrass and macroalgae within two lakes; St Georges Basin and Wallis Lake. Several patterns of association were observed, but these varied among species of sponge and ascidian. In St Georges Basin, the most common sponge, Aplysinella cf. rhax and the native ascidian Pyura stolonifera were positively correlated with the seagrass, Posidonia australis. In contrast, the introduced ascidian, Styela plicata was more abundant in areas dominated by the seagrass, Zostera capricorni. In Wallis Lake, sponges were most diverse and some species most abundant in large beds of the macroalga, Lamprothamnion sp., while other sponges were found only on the holdfasts of brown macroalgae. In both lakes, sponges were generally less common in areas dominated by dense meadows of the seagrass, Zostera capricorni.Among the many anthropogenic impacts threatening the ecology of coastal lakes, the discharge of cooling water from coal-fired power stations represents an almost ideal case study from which to develop appropriate sampling regimes for detecting impacts on sponges and ascidians. Using reference locations both within and outside Lake Macquarie which has two cooling water outlets, I found assemblages of sponges and ascidians were often more diverse, more abundant and less temporally variable near to the outlets compared to reference locations.Based on the observation that the sponge, Suberites sp. which contains photosynthetic symbionts was absent from meadows of dense Zostera capricorni, I used in situ manipulative experiments in Smiths Lake to investigate processes which maybe affecting their distribution. Individual Suberites sp. were shaded, had water flow reduced and were transplanted into areas of dense Z. capricorni. There were no measurable short-term effects of shading or reduced water flow, but transplanted sponges were quickly eaten and I concluded predation by fish was likely to be a key process determining small-scale patterns of distribution of Suberites sp. in seagrass meadows. This result was in stark contrast to the majority of previous studies of the effects of seagrass habitat complexity on predation which have found predation to decrease with increasing density or complexity.In conclusion, I have sought to provide sound scientific information to aid in the management of these systems. A simple, but nevertheless key finding was that sponges and ascidians are indeed present and widespread in coastal lakes and lagoons of southeastern Australia and should not be continually overlooked in the management and conservation of these systems. Conservation will be complex and requires an understanding of environmental impacts and the consequences of management on the full range of biodiversity. The distributions of sponges and ascidians at large ‘lakewide’ scales appear to behave similarly to other taxa. Management strategies which change the characteristics of a lake at these large spatial scales such as artificial openings of entrances could therefore be predicted to have similar effects across a range of taxa including sponges and ascidians. In contrast, at smaller spatial scales such as the complexity of seagrass meadows, some species of sponges and ascidians may behave very differently from other taxa. At present, our understanding of these naturally variable and complex systems is incomplete and will require ongoing scientific investigation to identify natural patterns of distribution, environmental impacts, important natural processes and the ecological consequences of management strategies.

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26

Rubio, Zuazo Ana Maria, and anarubio zuazo@gmail com. "Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two southeastern Australian estuaries." The Australian National University. Centre for Resource and Environmental Studies, 2008. http://thesis.anu.edu.au./public/adt-ANU20080618.091057.

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There has been a continuous decline in both the production and general performance of the SRO in NSW estuaries over the past three decades. The relationship of this decline to both environmental and oyster-density related factors are assessed in this thesis. This question has been examined at different scales: a large scale that compares two different estuaries (Clyde and Shoalhaven Rivers, southern NSW); a regional scale that encompasses variations within an estuary and, at a lease scale that examines processes pertaining to individual or small groups of oysters. Levels of inorganic nutrients were in general very low potentially limiting primary production. The limiting nutrient was nitrogen or phosphorus depending on whether long term conditions were dry or wet, respectively. Only during rain events, through the input of terrestrial material, were conditions favourable for fast rates of primary production. Carbon and nitrogen isotope analysis has demonstrated that both external material and local resuspension of the benthos constitute a major proportion of the SRO diet. The uptake of the various food sources also varied considerably depending on local environmental conditions. Increases in SRO growth were strongly correlated to increases in temperature with a low temperature cut-off at ~13°C. Growth also appeared to reduce considerably when salinities lower than ~15ppt persisted for the order of a month. These factors may alter growth through changes in filtration rates. These processes were modelled in a coupled hydrodynamic-NPO (Nitrogen-Phytoplankton-Oyster) model of the Clyde River. This demonstrated that primary production was more affected by estuarine dynamics and nutrient concentrations than oyster uptake. At the current levels of oyster densities, primary production by itself could not account for the observed oyster growth, however growth became realistic with observed levels of POC added to the model. A set of environmental indices were used to complement the model and to assess the sustainability of the culture system. The combined indices indicated that while the ecological carrying capacity of the Clyde was exceeded the production capacity at an estuarine scale was not. On the lease scale, density experiments showed that while growth was not reduced as a result of current stocking densities, the condition index was significantly affected.

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27

Rubio, Ana M. "Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two Southeastern Australian estuaries /." View thesis entry in Australian Digital Theses Program, 2007. http://thesis.anu.edu.au/public/adt-ANU20080618.091057/index.html.

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28

Griffin, Sandra Lenore. "Interactions between zooplankton grazers and phytoplankton as part of the energy and nutrient dynamics in the Swan River Estuary, Western Australia." Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/1928.

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Most Australian studies on estuarine plankton have examined distribution and abundance in relation to hydrological changes, primary productivity and associated nutrient dynamics. Relatively few have examined the complex interactions between zooplankton grazers and the type and quality of food available, or the role of zooplankton grazers in structuring phytoplankton communities, or their contribution to the nutrient pool. The ecological role of zooplankton grazers in the Swan River estuary, Perth, Western Australia, was examined as part of a collaborative research project directed by the Western Australian Estuarine Research Foundation, which was established in response to concern about increasing intensity and persistence of algal blooms. The present study focussed on one component of the zooplankton, the Copepoda, as model zooplankton grazers. A regular zooplankton monitoring programme, undertaken over a two year period, provided data on seasonal patterns of abundance and distribution of zooplankton over a broad spectrum of physical conditions. Relationships were identified between habitat variables, such as algal biomass, dissolved oxygen, salinity and suspended solids and zooplankton distribution, relative abundance and species composition. Prior to the inception of this study, it was assumed that copepod species composition, abundance and richness in the Swan River estuary may have changed over time, in response to long-term declines in water quality. Comparison of historical copepod monitoring data with current data did not detect any such change and it was concluded that there was greater variation in copepod species composition, abundance and richness within years than between years and that no significant change had occurred between 1966 and 1997.However, an absence or reduction in abundance of copepods in areas of very high algal biomass (>80 pg chlorophyll a.L-1) suggests that local loss of water quality may have an impact on copepods over a small spatial scale within the estuary. Different aspects of the interactions between zooplankton grazers and phytoplankton were studied. Zooplankton grazing rates were measured in situ during algal blooms and in the laboratory under controlled conditions to determine the potential for zooplankton grazers to reduce algal biomass. Field and laboratory experiments supported the hypothesis that copepods and other zooplankton can exert 'top-down control' over phytoplankton biomass, but that the type and biomass of phytoplankton present affected their ability to exert this control. The results of the field and laboratory grazing experiments, along with literature data, were used to provide input data for a model of zooplankton and phytoplankton dynamics during a dinoflagellate bloom in the Swan River estuary. The model was tested against biomass measurements of zooplankton and phytoplankton to determine how well it predicted actual changes in the plankton community. The simulated output closely followed the measured Page x field data and fitted regression curves and provided information about diurnal patterns of phytoplankton production, respiration and migration and hydrodynamic transport, which was not available from field data. It was shown that zooplankton grazing, particularly grazing by microzooplankton, was the process contributing most to the observed decline in dinoflagellate biomass. Nutrient availability is one of several factors determining productivity of phytoplankton. Nutrients within copepod faecal pellets are relocated by faecal deposition to sediments, where microbial activity leads to the remineralisation of these nutrients.Quantification of metabolic excretion of nutrients by copepods and the rate at which pellets are produced by copepod grazers, the concentration of nutrients within faecal pellets and the rate at which these nutrients are released indicated that copepods may play an important role in nutrient regeneration during summer and autumn when allochthonous nutrients are unavailable. At other times of the year, it is unlikely that copepods play an important role in nutrient regeneration. The research has provided a more detailed level of understanding of the interactions between zooplankton, phytoplankton and their environment. The data is ideally suited for use in a computer model to predict the effects of management actions on the Swan River estuary. This would allow pre-emptive management strategies to be developed and lessen the focus on reactive management.

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29

Young, Glen Christopher. "The fish fauna of two south-western Australian estuaries: Influence of an artificial entrance channel and of hypersalinity and prolonged closure." Thesis, Young, Glen Christopher (2000) The fish fauna of two south-western Australian estuaries: Influence of an artificial entrance channel and of hypersalinity and prolonged closure. PhD thesis, Murdoch University, 2000. https://researchrepository.murdoch.edu.au/id/eprint/52019/.

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The work undertaken for this thesis had the following two broad aims. The first was to determine the characteristics of the fish fauna of the Peel-Harvey Estuary in the mid 1990s, soon after the construction of a large artificial channel, the Dawesville Channel, into this estuary, and to compare these characteristics with those recorded in the early 1980s and thus prior to the construction of that channel. The second was to determine the characteristics of the ichthyofauna of the normally closed Wellstead Estuary, focusing in particular on elucidating the influence of both the extremely high salinities that are found in this system and the opening of the estuary mouth which occurs when freshwater discharge is sufficiently strong to breach the large sand bar at that mouth. The fish larvae on flood and ebb tides in the artificial Dawesville channel and the original Mandurah Channel of the Peel-Harvey Estuary were sampled at monthly intervals during 1997 using bongo nets. Postlarval, juvenile and adult fish in the Mandurah Channel and two regions in each of the large basins (Peel Inlet and Harvey Estuary) were sampled at regular intervals between the end of 1995 and end of 1997 using seine nets that were 5.5, 21.5 and 102.5 m in length. Nearshore, shallow and offshore, deeper waters of Wellstead Estuary were sampled at eight-weekly intervals between July 1996 and May 1998 using a 41.5 m seine net and composite gill nets, respectively. The number of fish species caught as larvae was far greater in the Dawesville Channel (49) than in the Mandurah Channel (34), a difference that was mainly due to a far greater number of marine stragglers, and often reef-associated species, in the former channel. The difference in number of species is presumably related to the presence of a better developed reef system just outside the Dawesville Channel and the fact that the velocity and volume of tidal water that is exchanged through this channel is much greater than through the Mandurah Channel. The number of fish larvae caught on flood tides was greater than on ebb tides in both channels, which suggests some individuals of marine species settle in the shallow and slower flowing regions in the channels or just inside the basins. Favonigobius lateralis and Atherinosoma elongata, which spawn in the estuary, tend to be transported out as preflexion larvae on ebb tides and inwards as postflexion larvae on flood tides. The species composition of the ichthyoplankton on both the flood and ebb tides in both channels underwent pronounced and consistent cyclical changes throughout the year, which was clearly related to differences in the spawning times of the various species within and outside the estuary. The catches of postlarval and early 0+ juvenile fish provide very strong evidence that the majority of marine species, that were caught as larvae on flood and ebb tides in the Mandurah and Dawesville channels, do not become established in the basins of the Peel-Harvey Estuary. However, the catch and length-frequency data for Hyperlophas vittatus indicated that large numbers of this clupeid enter this estuary as postlarvae, settle soon after they enter the estuary and then subsequently slowly penetrate into the basins. The use of Classification and Multidimensional scaling ordination demonstrated that the species composition of the fish fauna of nearshore, shallow waters in the large basins of the Peel-Harvey Estuary during the 1980s was influenced more by region within the estuary than by time of year, whereas the reverse pertained in the mid-1990s. The shift to a strong seasonal influence on species composition in the latter period is presumably related to the far greater tidal water movement that now occurs in the basin regions as a result of the constmction of the Dawesville Channel. This seasonality in the basins is attributable, in part, to differences in the patterns of immigration and emigration exhibited by the juveniles of marine species. The number of species and overall density of fish were positively correlated with salinity and inversely correlated with distance from estuary mouth. This trend was followed by all species except Leptatherina wallacei, which is known typically to occupy the upper reaches of estuaries where salinities are reduced. Since the construction of the Dawesville Channel, the density of fish in Peel Inlet has declined, presumably due to the reduction in the amount of macroalgae. Prior to the construction of the Dawesville Channel, when the basins, and in particular Peel Inlet, contained massive growths of macroalgae, the fauna of these regions was dominated by three weed-associated species, namely Relates sexlineatus, Apogon rueppellii and Genes sub fascial us. Although these species thus contributed nearly 60% to the total number of fish caught in the early 1980s, they contributed only about 8% in the mid 1990s after the construction of the Dawesville Channel, when, as a result of increased Hushing, there was a reduction in macroalgae. The construction of the Dawesville Channel has resulted in the Harvey Estuary becoming (1) directly connected with the ocean at its northern and seaward end, (2) better flushed and (3) far less susceptible to the development of blue-green algal blooms in the spring and early summer, which had previously been shown to have a deleterious effect on fish abundance. These changes account for the greater number of fish species and greater densities of fish that were recorded in the post- Dawesville period than pre- Dawesville period. Wellstead Estuary remained closed between October 1993 and September 1997 and then opened for just under a month, before once again becoming closed until the end of April 1998 when it opened and remained so until the end of the 24 month sampling period in May 1998. During the study period, mean monthly salinities underwent massive seasonal variations and sometimes varied markedly between regions. For example, mean monthly salinities in the lower estuary rose from 52.9%c in July 1996 to 111.7%c in the following March, before declining precipitously to 14.3%c in September 1997. In March 1997, they ranged greatly from 63.0%c in the upper estuary to 111.7%o in the lower estuary. A total of only 20 species were caught using seine and gill nets throughout this estuary. Not surprisingly, the fish fauna in nearshore, shallow waters was dominated by species which spawn in the estuary, with these species contributing over 98% of all fish caught. In contrast, marine species contributed approximately 58% of the fish caught in offshore, deeper waters. These species were larger teleosts which live for a number of years and moved in and out of the estuary when the bar at the estuary mouth was breached. The species composition in nearshore, shallow waters changed progressively and significantly between the lower, middle and upper estuary, reflecting in part the greater densities of Atherinosoma elongata and Aldrichetta forsteri towards the lower end of the estuary and of Acanthopagrus butcheri, Leptatherina presbyteroides. Pseudogobius olorum and Leptatherina wallacei towards the upper end. Since the fish typically found in nearshore, shallow waters represented species that complete their life cycles within estuaries, it is not surprising that the species composition did not change when the estuary mouth opened. In contrast, the species composition in offshore, deeper waters did not vary among regions but did change after the estuary mouth became open. This change in composition was due to the emigration of Mugil cephalus and Aldrichetta forsteri and the immigration of Arripis georgiana, Arripis truttaceus and Pomatomus saltatrix.

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30

Wildsmith, Michelle Deanne. "Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia /." Access via Murdoch University Digital Theses Project, 2007. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081029.93910.

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31

Griffin, Sandra Lenore. "Interactions between zooplankton grazers and phytoplankton as part of the energy and nutrient dynamics in the Swan River Estuary, Western Australia." Curtin University of Technology, School of Chemical and Biological Sciences, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=14320.

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Most Australian studies on estuarine plankton have examined distribution and abundance in relation to hydrological changes, primary productivity and associated nutrient dynamics. Relatively few have examined the complex interactions between zooplankton grazers and the type and quality of food available, or the role of zooplankton grazers in structuring phytoplankton communities, or their contribution to the nutrient pool. The ecological role of zooplankton grazers in the Swan River estuary, Perth, Western Australia, was examined as part of a collaborative research project directed by the Western Australian Estuarine Research Foundation, which was established in response to concern about increasing intensity and persistence of algal blooms. The present study focussed on one component of the zooplankton, the Copepoda, as model zooplankton grazers. A regular zooplankton monitoring programme, undertaken over a two year period, provided data on seasonal patterns of abundance and distribution of zooplankton over a broad spectrum of physical conditions. Relationships were identified between habitat variables, such as algal biomass, dissolved oxygen, salinity and suspended solids and zooplankton distribution, relative abundance and species composition. Prior to the inception of this study, it was assumed that copepod species composition, abundance and richness in the Swan River estuary may have changed over time, in response to long-term declines in water quality. Comparison of historical copepod monitoring data with current data did not detect any such change and it was concluded that there was greater variation in copepod species composition, abundance and richness within years than between years and that no significant change had occurred between 1966 and 1997.
However, an absence or reduction in abundance of copepods in areas of very high algal biomass (>80 pg chlorophyll a.L-1) suggests that local loss of water quality may have an impact on copepods over a small spatial scale within the estuary. Different aspects of the interactions between zooplankton grazers and phytoplankton were studied. Zooplankton grazing rates were measured in situ during algal blooms and in the laboratory under controlled conditions to determine the potential for zooplankton grazers to reduce algal biomass. Field and laboratory experiments supported the hypothesis that copepods and other zooplankton can exert 'top-down control' over phytoplankton biomass, but that the type and biomass of phytoplankton present affected their ability to exert this control. The results of the field and laboratory grazing experiments, along with literature data, were used to provide input data for a model of zooplankton and phytoplankton dynamics during a dinoflagellate bloom in the Swan River estuary. The model was tested against biomass measurements of zooplankton and phytoplankton to determine how well it predicted actual changes in the plankton community. The simulated output closely followed the measured Page x field data and fitted regression curves and provided information about diurnal patterns of phytoplankton production, respiration and migration and hydrodynamic transport, which was not available from field data. It was shown that zooplankton grazing, particularly grazing by microzooplankton, was the process contributing most to the observed decline in dinoflagellate biomass. Nutrient availability is one of several factors determining productivity of phytoplankton. Nutrients within copepod faecal pellets are relocated by faecal deposition to sediments, where microbial activity leads to the remineralisation of these nutrients.
Quantification of metabolic excretion of nutrients by copepods and the rate at which pellets are produced by copepod grazers, the concentration of nutrients within faecal pellets and the rate at which these nutrients are released indicated that copepods may play an important role in nutrient regeneration during summer and autumn when allochthonous nutrients are unavailable. At other times of the year, it is unlikely that copepods play an important role in nutrient regeneration. The research has provided a more detailed level of understanding of the interactions between zooplankton, phytoplankton and their environment. The data is ideally suited for use in a computer model to predict the effects of management actions on the Swan River estuary. This would allow pre-emptive management strategies to be developed and lessen the focus on reactive management.

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32

au, m. hourston@iinet net, and Mathew Hourston. "The ecology of free-living nematodes in nearshore marine and estuarine sediments of the microtidal lower west coast of Australia." Murdoch University, 2009. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20100512.85739.

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The overarching aim of this thesis was to describe the ecology of the assemblages of free-living nematodes in the sediments of nearshore marine and estuarine waters on the microtidal lower west coast of Australia. The thesis also provides descriptions of ten previously undescribed species as well as develops and tests a habitat classification scheme for the Swan River Estuary using these biotic assemblages. The first section of my thesis has determined the ways in which the characteristics of the nematode assemblages in nearshore marine waters along the microtidal lower west coast of Australia are related to habitat type, time of year and shore-perpendicular zones. Three habitat types, which had previously been identified on the basis of a suite of enduring environmental characteristics, could be broadly described as highly sheltered from wave activity and containing dense seagrass (habitat type 1), moderately sheltered from wave activity and with sparse seagrass (habitat type 2) and relatively exposed to wave activity and with no seagrass (habitat type 6). Sampling in five consecutive seasons yielded > 15 000 nematodes, representing 75 species. The number of species and densities in habitat type 1, and particularly those in its subtidal zone, were far greater than those in the other two habitat types. Both of these biotic variables underwent marked seasonal changes, declining to low levels during winter. The compositions of the assemblages differed significantly among the three habitat types, with the differences between habitat types 1 and 6 being particularly marked. Paracomesoma sipho, Dichromadora sp., Marylynnia annae and Pomponema sp., which, on the basis of their buccal cavity morphology, are assumed to feed primarily on benthic diatoms, were particularly abundant at the most sheltered habitat type, whereas Gonionchus australis, Theristus sp. and Bathylaimus australis, which are assumed to be deposit feeders, were relatively abundant at the most highly exposed habitat type. The compositions of the assemblages differed among seasons and were most discrete in spring, due to marked increases in the densities of certain species. However, differences in the compositions in the different zones of each habitat type were relatively small, presumably reflecting the influence of the small tidal regime of this region. The second component of this thesis has determined the ways in which the density, number of species, species composition and trophic structure of free-living nematode assemblages in the subtidal waters of a large microtidal estuary change spatially and temporally, and has explored whether those four biotic characteristics are related to certain environmental factors. Based on data derived from samples collected seasonally at 12 sites throughout the estuary, the densities and number of species of nematodes decreased progressively with distance from estuary mouth, to reach a minimum at sites where salinities were most variable, and then increased slightly in the uppermost part of the estuary where salinities were least. Densities were also generally greatest in spring, due largely to increases in the abundance of epistrate-grazing species at the time when the amount of primary food (microphytobenthos) peaked. The spatial distribution of the composition of the nematode assemblages was closely correlated with salinity and, to a lesser extent, grain-size composition and amount of particulate organic material in the sediment (%POM). Although species composition changed sequentially along the estuary, the change was particularly pronounced between sites above and below the area where salinities started to decline markedly and become more variable and %POM increased markedly. This reflected, in particular, far greater abundances of Spirinia parasitifera at the six downstream sites, and of Theristus sp. 1 at the six sites further upstream. Species composition underwent pronounced seasonal cyclical changes at all sites, presumably reflecting interspecific differences in the timing of peak reproduction and thus of recruitment. The trophic structure of the nematode assemblages changed both spatially and temporally in relation to the relative abundance of different food sources. Thus, for example, non-selective deposit feeders, such as Theristus sp. 1, dominated samples in the upper estuary, where %POM was by far the greatest, and was rare or absent at downstream sites. Conversely, epistrate grazers, such as species of the Chromadoridae, were most abundant at downstream sites in spring, when the density of the microphytobenthos reached its maximum. The data for the nematode assemblages in nearshore subtidal marine sediments of the lower west coast of Australia were compared with those in nearshore subtidal sediments in the upper and lower regions of the Swan River Estuary. The densities and average species richness in cores from the marine environment were much lower than in cores from both estuarine regions. However, the total number of species found in the marine environment was much greater than in the estuary. The compositions of the nematode assemblages were more variable in marine than estuarine sediments. The assemblages from the two estuarine regions were far more similar to each other than to those from the marine region at a species level, and also, but to a lesser extent, at the generic and family levels. While the trophic compositions of the nematode assemblages in the upper estuarine region was dominated by non-selective deposit feeding species and those of the lower estuarine region were dominated by epistrate grazing species during spring and non-selective deposit feeding species in other seasons, the dominant functional feeding groups varied among the sites representing the marine region. That variability presumably reflects differences in the relative contributions of the different potential food sources. Surprisingly, the trophic composition in the upper estuarine region, i.e. comprising predominantly non-selective deposit feeders, was similar to that at the very different environment of the most exposed marine site. The dominance of this feeding group at the marine site is assumed to be attributable to the fact that the only food source of any note is POM and, even then, it occurs in only small amounts. Taxonomic descriptions have been produced for ten new species of nematodes found during the ecological studies of the free-living aquatic nematofaunas of south-western Australia. These species were chosen because they were members of families for which the other species had been described and, in a number of cases, were important for distinguishing between the compositions of a priori groups. They comprised four species of Axonolaimidae, representing the genera Ascolaimus, Parascolaimus, Odontophora and Parodontophora, and six species of Desmodoridae, representing single species of Bolbonema, Eubostrichus, Catanema and Leptonemella and two species of Onyx. As a complement to the nematological study of the Swan River Estuary, a novel habitat classification system was developed and then applied in this environment. This system was based on enduring environmental characteristics and employed the relatively new multivariate statistical routines SIMPROF and LINKTREE. The applicability of habitat types produced by this classification system to biotic assemblages was tested using the data for the estuarine nematode assemblages described above. The results demonstrate that the compositions of the assemblages differed significantly among each of the habitat types defined by the classification system. While there were also significant differences between the compositions of the nematofaunas at sites belonging to the same habitat type, the extent of these differences were generally less than those between habitat types. A significant and strong correlation was also found between the spatial pattern exhibited by the environmental characteristics used to define habitat types, and that of the nematofauna.

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33

Hourston, Mathew. "The ecology of free-living nematodes in nearshore marine and estuarine sediments of the microtidal lower west coast of Australia." Thesis, Hourston, Mathew (2009) The ecology of free-living nematodes in nearshore marine and estuarine sediments of the microtidal lower west coast of Australia. PhD thesis, Murdoch University, 2009. https://researchrepository.murdoch.edu.au/id/eprint/1672/.

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Анотація:

The overarching aim of this thesis was to describe the ecology of the assemblages of free-living nematodes in the sediments of nearshore marine and estuarine waters on the microtidal lower west coast of Australia. The thesis also provides descriptions of ten previously undescribed species as well as develops and tests a habitat classification scheme for the Swan River Estuary using these biotic assemblages. The first section of my thesis has determined the ways in which the characteristics of the nematode assemblages in nearshore marine waters along the microtidal lower west coast of Australia are related to habitat type, time of year and shore-perpendicular zones. Three habitat types, which had previously been identified on the basis of a suite of enduring environmental characteristics, could be broadly described as highly sheltered from wave activity and containing dense seagrass (habitat type 1), moderately sheltered from wave activity and with sparse seagrass (habitat type 2) and relatively exposed to wave activity and with no seagrass (habitat type 6). Sampling in five consecutive seasons yielded > 15 000 nematodes, representing 75 species. The number of species and densities in habitat type 1, and particularly those in its subtidal zone, were far greater than those in the other two habitat types. Both of these biotic variables underwent marked seasonal changes, declining to low levels during winter. The compositions of the assemblages differed significantly among the three habitat types, with the differences between habitat types 1 and 6 being particularly marked. Paracomesoma sipho, Dichromadora sp., Marylynnia annae and Pomponema sp., which, on the basis of their buccal cavity morphology, are assumed to feed primarily on benthic diatoms, were particularly abundant at the most sheltered habitat type, whereas Gonionchus australis, Theristus sp. and Bathylaimus australis, which are assumed to be deposit feeders, were relatively abundant at the most highly exposed habitat type. The compositions of the assemblages differed among seasons and were most discrete in spring, due to marked increases in the densities of certain species. However, differences in the compositions in the different zones of each habitat type were relatively small, presumably reflecting the influence of the small tidal regime of this region. The second component of this thesis has determined the ways in which the density, number of species, species composition and trophic structure of free-living nematode assemblages in the subtidal waters of a large microtidal estuary change spatially and temporally, and has explored whether those four biotic characteristics are related to certain environmental factors. Based on data derived from samples collected seasonally at 12 sites throughout the estuary, the densities and number of species of nematodes decreased progressively with distance from estuary mouth, to reach a minimum at sites where salinities were most variable, and then increased slightly in the uppermost part of the estuary where salinities were least. Densities were also generally greatest in spring, due largely to increases in the abundance of epistrate-grazing species at the time when the amount of primary food (microphytobenthos) peaked. The spatial distribution of the composition of the nematode assemblages was closely correlated with salinity and, to a lesser extent, grain-size composition and amount of particulate organic material in the sediment (%POM). Although species composition changed sequentially along the estuary, the change was particularly pronounced between sites above and below the area where salinities started to decline markedly and become more variable and %POM increased markedly. This reflected, in particular, far greater abundances of Spirinia parasitifera at the six downstream sites, and of Theristus sp. 1 at the six sites further upstream. Species composition underwent pronounced seasonal cyclical changes at all sites, presumably reflecting interspecific differences in the timing of peak reproduction and thus of recruitment. The trophic structure of the nematode assemblages changed both spatially and temporally in relation to the relative abundance of different food sources. Thus, for example, non-selective deposit feeders, such as Theristus sp. 1, dominated samples in the upper estuary, where %POM was by far the greatest, and was rare or absent at downstream sites. Conversely, epistrate grazers, such as species of the Chromadoridae, were most abundant at downstream sites in spring, when the density of the microphytobenthos reached its maximum. The data for the nematode assemblages in nearshore subtidal marine sediments of the lower west coast of Australia were compared with those in nearshore subtidal sediments in the upper and lower regions of the Swan River Estuary. The densities and average species richness in cores from the marine environment were much lower than in cores from both estuarine regions. However, the total number of species found in the marine environment was much greater than in the estuary. The compositions of the nematode assemblages were more variable in marine than estuarine sediments. The assemblages from the two estuarine regions were far more similar to each other than to those from the marine region at a species level, and also, but to a lesser extent, at the generic and family levels. While the trophic compositions of the nematode assemblages in the upper estuarine region was dominated by non-selective deposit feeding species and those of the lower estuarine region were dominated by epistrate grazing species during spring and non-selective deposit feeding species in other seasons, the dominant functional feeding groups varied among the sites representing the marine region. That variability presumably reflects differences in the relative contributions of the different potential food sources. Surprisingly, the trophic composition in the upper estuarine region, i.e. comprising predominantly non-selective deposit feeders, was similar to that at the very different environment of the most exposed marine site. The dominance of this feeding group at the marine site is assumed to be attributable to the fact that the only food source of any note is POM and, even then, it occurs in only small amounts. Taxonomic descriptions have been produced for ten new species of nematodes found during the ecological studies of the free-living aquatic nematofaunas of south-western Australia. These species were chosen because they were members of families for which the other species had been described and, in a number of cases, were important for distinguishing between the compositions of a priori groups. They comprised four species of Axonolaimidae, representing the genera Ascolaimus, Parascolaimus, Odontophora and Parodontophora, and six species of Desmodoridae, representing single species of Bolbonema, Eubostrichus, Catanema and Leptonemella and two species of Onyx. As a complement to the nematological study of the Swan River Estuary, a novel habitat classification system was developed and then applied in this environment. This system was based on enduring environmental characteristics and employed the relatively new multivariate statistical routines SIMPROF and LINKTREE. The applicability of habitat types produced by this classification system to biotic assemblages was tested using the data for the estuarine nematode assemblages described above. The results demonstrate that the compositions of the assemblages differed significantly among each of the habitat types defined by the classification system. While there were also significant differences between the compositions of the nematofaunas at sites belonging to the same habitat type, the extent of these differences were generally less than those between habitat types. A significant and strong correlation was also found between the spatial pattern exhibited by the environmental characteristics used to define habitat types, and that of the nematofauna.

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34

Hourston, Mathew. "The ecology of free-living nematodes in nearshore marine and estuarine sediments of the microtidal lower west coast of Australia." Hourston, Mathew (2009) The ecology of free-living nematodes in nearshore marine and estuarine sediments of the microtidal lower west coast of Australia. PhD thesis, Murdoch University, 2009. http://researchrepository.murdoch.edu.au/1672/.

Повний текст джерела

Анотація:

The overarching aim of this thesis was to describe the ecology of the assemblages of free-living nematodes in the sediments of nearshore marine and estuarine waters on the microtidal lower west coast of Australia. The thesis also provides descriptions of ten previously undescribed species as well as develops and tests a habitat classification scheme for the Swan River Estuary using these biotic assemblages. The first section of my thesis has determined the ways in which the characteristics of the nematode assemblages in nearshore marine waters along the microtidal lower west coast of Australia are related to habitat type, time of year and shore-perpendicular zones. Three habitat types, which had previously been identified on the basis of a suite of enduring environmental characteristics, could be broadly described as highly sheltered from wave activity and containing dense seagrass (habitat type 1), moderately sheltered from wave activity and with sparse seagrass (habitat type 2) and relatively exposed to wave activity and with no seagrass (habitat type 6). Sampling in five consecutive seasons yielded > 15 000 nematodes, representing 75 species. The number of species and densities in habitat type 1, and particularly those in its subtidal zone, were far greater than those in the other two habitat types. Both of these biotic variables underwent marked seasonal changes, declining to low levels during winter. The compositions of the assemblages differed significantly among the three habitat types, with the differences between habitat types 1 and 6 being particularly marked. Paracomesoma sipho, Dichromadora sp., Marylynnia annae and Pomponema sp., which, on the basis of their buccal cavity morphology, are assumed to feed primarily on benthic diatoms, were particularly abundant at the most sheltered habitat type, whereas Gonionchus australis, Theristus sp. and Bathylaimus australis, which are assumed to be deposit feeders, were relatively abundant at the most highly exposed habitat type. The compositions of the assemblages differed among seasons and were most discrete in spring, due to marked increases in the densities of certain species. However, differences in the compositions in the different zones of each habitat type were relatively small, presumably reflecting the influence of the small tidal regime of this region. The second component of this thesis has determined the ways in which the density, number of species, species composition and trophic structure of free-living nematode assemblages in the subtidal waters of a large microtidal estuary change spatially and temporally, and has explored whether those four biotic characteristics are related to certain environmental factors. Based on data derived from samples collected seasonally at 12 sites throughout the estuary, the densities and number of species of nematodes decreased progressively with distance from estuary mouth, to reach a minimum at sites where salinities were most variable, and then increased slightly in the uppermost part of the estuary where salinities were least. Densities were also generally greatest in spring, due largely to increases in the abundance of epistrate-grazing species at the time when the amount of primary food (microphytobenthos) peaked. The spatial distribution of the composition of the nematode assemblages was closely correlated with salinity and, to a lesser extent, grain-size composition and amount of particulate organic material in the sediment (%POM). Although species composition changed sequentially along the estuary, the change was particularly pronounced between sites above and below the area where salinities started to decline markedly and become more variable and %POM increased markedly. This reflected, in particular, far greater abundances of Spirinia parasitifera at the six downstream sites, and of Theristus sp. 1 at the six sites further upstream. Species composition underwent pronounced seasonal cyclical changes at all sites, presumably reflecting interspecific differences in the timing of peak reproduction and thus of recruitment. The trophic structure of the nematode assemblages changed both spatially and temporally in relation to the relative abundance of different food sources. Thus, for example, non-selective deposit feeders, such as Theristus sp. 1, dominated samples in the upper estuary, where %POM was by far the greatest, and was rare or absent at downstream sites. Conversely, epistrate grazers, such as species of the Chromadoridae, were most abundant at downstream sites in spring, when the density of the microphytobenthos reached its maximum. The data for the nematode assemblages in nearshore subtidal marine sediments of the lower west coast of Australia were compared with those in nearshore subtidal sediments in the upper and lower regions of the Swan River Estuary. The densities and average species richness in cores from the marine environment were much lower than in cores from both estuarine regions. However, the total number of species found in the marine environment was much greater than in the estuary. The compositions of the nematode assemblages were more variable in marine than estuarine sediments. The assemblages from the two estuarine regions were far more similar to each other than to those from the marine region at a species level, and also, but to a lesser extent, at the generic and family levels. While the trophic compositions of the nematode assemblages in the upper estuarine region was dominated by non-selective deposit feeding species and those of the lower estuarine region were dominated by epistrate grazing species during spring and non-selective deposit feeding species in other seasons, the dominant functional feeding groups varied among the sites representing the marine region. That variability presumably reflects differences in the relative contributions of the different potential food sources. Surprisingly, the trophic composition in the upper estuarine region, i.e. comprising predominantly non-selective deposit feeders, was similar to that at the very different environment of the most exposed marine site. The dominance of this feeding group at the marine site is assumed to be attributable to the fact that the only food source of any note is POM and, even then, it occurs in only small amounts. Taxonomic descriptions have been produced for ten new species of nematodes found during the ecological studies of the free-living aquatic nematofaunas of south-western Australia. These species were chosen because they were members of families for which the other species had been described and, in a number of cases, were important for distinguishing between the compositions of a priori groups. They comprised four species of Axonolaimidae, representing the genera Ascolaimus, Parascolaimus, Odontophora and Parodontophora, and six species of Desmodoridae, representing single species of Bolbonema, Eubostrichus, Catanema and Leptonemella and two species of Onyx. As a complement to the nematological study of the Swan River Estuary, a novel habitat classification system was developed and then applied in this environment. This system was based on enduring environmental characteristics and employed the relatively new multivariate statistical routines SIMPROF and LINKTREE. The applicability of habitat types produced by this classification system to biotic assemblages was tested using the data for the estuarine nematode assemblages described above. The results demonstrate that the compositions of the assemblages differed significantly among each of the habitat types defined by the classification system. While there were also significant differences between the compositions of the nematofaunas at sites belonging to the same habitat type, the extent of these differences were generally less than those between habitat types. A significant and strong correlation was also found between the spatial pattern exhibited by the environmental characteristics used to define habitat types, and that of the nematofauna.

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35

au, M. Wildsmith@murdoch edu, and Michelle Wildsmith. "Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia." Murdoch University, 2007. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081029.93910.

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The following four broad aims were addressed in this study. (1) To ascertain whether the characteristics of the benthic macroinvertebrate assemblages within the different nearshore marine habitat types identified by Valesini et al. (2003) on the lower west coast of Australia differ significantly, and whether the pattern of those spatial differences matches those among the environmental characteristics that were used to distinguish those habitat types; (2) To develop a quantitative approach for classifying nearshore habitats in estuarine waters that employs readily-available data for a range of enduring environmental characteristics, and to use that approach to classify the various habitat types present in nearshore waters of the Swan-Canning Estuary on the lower west coast of Australia; (3) To test the hypothesis that the characteristics of the benthic macroinvertebrate assemblages in the in the Swan-Canning Estuary differ significantly among nearshore habitat types, and that the pattern of those differences matches that among the environmental characteristics used to distinguish those habitat types and (4) To test the hypothesis that, as a result of environmental changes in the Swan-Canning Estuary, the characteristics of the benthic macroinvertebrate assemblages at various habitats in this estuary in 1986/7 differ from those in 2003/4. To address the first aim, benthic macroinvertebrates were sampled seasonally for one year in the subtidal waters and intertidal zone (upper and lower swash zones) at the six nearshore habitat types that were identified by Valesini et al. (2003) on the lower west coast of Australia. The habitat types, which differed mainly in the extent of their exposure to wave activity and whether seagrass and/or nearshore reefs were present, had been distinguished quantitatively using values for a suite of seven statistically-selected enduring environmental characteristics. The faunal samples yielded a total of 121 species representing eight phyla, among which the Polychaeta, Malacostraca and Bivalvia were the most speciose classes and contributed ~ 38, 23 and 10%, respectively, to the total number of individuals. The total number of species and mean density of macroinvertebrates was far greater at the most protected habitat type (1), which also contained dense beds of seagrass, than at any other habitat type, i.e. 70 species and 209.2 individuals 0.1 m-2, compared to 32 species and 36.9 individuals 0.1 m-2 at the most exposed habitat type (6), which had a substrate comprised only of sand. Differences among habitat type influenced the benthic macroinvertebrate species composition to a greater extent than differences among either zones or seasons. Significantly different faunal compositions were detected among those latter two factors only at the most protected habitat type. The faunal assemblage at habitat type 1 was clearly the most distinct from those at the other five habitat types, particularly in the subtidal zone (R-statistics=0.642-0.831, p=0.1%), and was typified by five abundant polychaete species that were adapted to deposit-feeding. In contrast, the fauna at habitat type 6 was typified by four crustacean species and a species of bivalve and polychaete, whose mobility and tough external surface facilitated their survival and feeding in those turbulent waters. The extents of the differences in species composition among the six habitat types was significantly matched with that among the suite of enduring environmental characteristics that distinguished those habitat types, particularly in the case of the subtidal zone (Rho=0.676). Such results indicated that the environmental variables used to distinguish the nearshore habitat types could be used to reliably predict the types of benthic macroinvertebrate species likely to occur at any site along the lower west coast of Australia. The above biological validation of the nearshore marine habitat classification scheme developed by Valesini et al. (2003) provided the justification for the approach to the second broad aim of this study, namely to develop a quantitative scheme for classifying habitat types in the Swan-Canning Estuary. This approach was similar to that employed by Valesini et al. (2003) in that it considers that differences among habitat types are well reflected by differences in a suite of enduring environmental variables. However, it improves on that earlier method by employing a completely objective and quantitative approach. Thus, a large number of environmentally-diverse nearshore sites (102) were initially selected throughout the Swan-Canning Estuary and a suite of 13 enduring environmental variables quantified at each using remotely-sensed images of the estuary in a Geographic Information System. Such variables were chosen to reflect either (i) the type of substrate and submerged vegetation present, (ii) the extent of exposure to wave action or (iii) the location of the site within the estuary with respect to its vicinity to marine and fresh water sources. These data were then subjected to the CLUSTER routine and associated SIMPROF procedure in the PRIMER v6 multivariate statistical package to quantitatively identify those groups of sites that did not differ significantly in their environmental characteristics, and thus represented habitat types. Eighteen habitat types were identified, which were shown to well reflect spatial differences in a suite of non-enduring water quality and sediment characteristics that were measured in situ at a range of estuarine sites during both summer and winter in 2005 (Rho=0.683 and 0.740, respectively, p=0.1%). However, those latter environmental characteristics required far more time in the field and laboratory to quantify than the enduring variables used to identify the habitat types. Benthic macroinvertebrates were sampled during summer and winter in 2005 in the shallow subtidal regions (~1 m depth) at sites representing eight of the habitat types identified in the Swan-Canning Estuary. These samples contained a total of 51 and 36 species during summer and winter, respectively, and, in both seasons, represented nine phyla, namely Annelida, Crustacea, Mollusca, Sipuncula, Nematoda, Platyhelminthes, Cnidaria, Uniramia and Nemertea. The compositions of the benthic macroinvertebrate assemblages differed significantly among habitat types and, to a similar extent, between seasons (Global R-statistic=0.408 and 0.409, respectively, p=0.1%). However, the spatial differences were considerable greater in winter than in summer (Global R-statistic=0.536 vs 0.280, p=0.1%), presumably due to the greater spatial variation in particular non-enduring in situ environmental characteristics, such as redox depth and salinity. While the number of species, overall density and taxonomic distinctness of benthic macroinvertebrates also differed significantly among habitats, those variables differed to a greater extent between seasons, being greater in winter than in summer. While the measures of taxonomic distinctness tended to be greater at habitat types located in the lower to middle reaches, i.e. habitat types 6, 7, 9, 10, 13 and 18, than the upper reaches i.e. habitat types 1 and 3, the number of species and overall density reflected this trend only during winter. During summer, the mean numbers of species at habitat types 1, 3, 6 and 10 (3.4-6.0) were significantly lower than those at habitat types 7, 13, and 18 (8.8-10.9), whereas the overall density of benthic macroinvertebrates was far greater at habitat type 7 (32260 individuals 0.1 m-2)than at any other habitat type in this season (3135-18552 individuals 0.1 m-2). Overall, the greatest differences in assemblage composition occurred between those at habitat types 1 and 18 (R-statistic=0.669, p=0.1%), which were located in the uppermost region of the estuary and the lower reaches of the basin, respectively, and differed to the greatest extent in their enduring environmental characteristics. The assemblage at habitat type 1, and also that at habitat type 3, located just downstream, were relatively distinct from those at all other habitat types, particularly during winter (R-statistics=0.666-0.993, p=0.1%). The fauna at the first of these habitat types was relatively depauperate, containing low numbers of species and densities, and was characterised by the polychaetes Leitoscoloplos normalis and Ceratonereis aequisetis and the bivalve Arthritica semen. The assemblage at habitat type 3 was also characterised by those three species and the amphipod Paracorophium minor and the polychaete Boccardiella limnicola. In contrast, the assemblage at habitat type 18 was characterised by a more diverse assemblage, i.e. the polychaetes Capitella capitata, C. aequisetis, L. normalis and Pseudopolydora kempi, the amphipods, Grandidierella propodentata and Corophium minor and the bivalve Sanguinolaria biradiata. The number of species was among the highest at this habitat type during both seasons, which was also reflected in the high taxonomic diversity, and the overall density was the highest in winter and second highest in summer. Despite the above faunal differences, those between assemblages at habitat types 7 and 9, which were both located in the basin of the Swan-Canning Estuary, were similar in magnitude to those that occurred between pairs of habitat types located in two different regions of the estuary. Although both habitat types 7 and 9 were characterised by a similar suite of species, i.e. Oligochaete spp., C. aequisetis, C. capitata, C. minor, G. propodentata, L. normalis, and S. biradiata, the substantial differences in assemblage composition between these habitat types in both summer and winter (R-statistics=0.570 and 0.725, respectively) was due to marked differences in the relative contributions of each of these species. Significant and strong correlations were shown to exist in both summer and winter between the pattern of differences in the benthic macroinvertebrate assemblages among habitat types and that among the enduring environmental characteristics used to identify those habitat types (Rho=0.625 and 0.825, respectively, p=0.1%). Furthermore, these correlations were greater than those obtained between the benthic macroinvertebrate fauna and any combination of the non-enduring environmental characteristics (i.e. water quality and sediment parameters) recorded in situ at each habitat type (Rho=0.508 and 0.824, in summer and winter, respectively, p=o.1%). This demonstrates the greater capacity of surrogate enduring environmental characteristics to account for differences in the range of variables that may influence the distribution of benthic invertebrate fauna. Thus, the lists of characteristic benthic macroinvertebrate taxa produced for each of the eight habitat types studied in the Swan-Canning Estuary provide a reliable benchmark by which to gauge any future changes in those fauna. Moreover, these results indicate that the above habitat classification scheme can be used to reliably predict the types of benthic macroinvertebrate fauna that are likely to occur at any nearshore site of interest in this estuarine system. The final component of this study showed that the benthic macroinvertebrate assemblages at four sites in the middle reaches of the Swan-Canning Estuary in 2003/4 differed significantly from those recorded at the same sites in 1986/7. Such differences were reflected in (1) changes in the relative densities of a suite of ten species that were responsible for distinguishing the faunas in these two periods, (2) the absence of 22 rare species in 2003/4 (i.e. 42% of the number of species recorded in 1986/7), (3) the presence of 17 new species in 2003/4, including an abundant polychaete that is likely to have been introduced and (4) a far greater extent of seasonal variation in the number of species and densities of benthic macroinvertebrates in 2003/4. Such changes are likely to be related to lower sediment oxygen levels in certain seasons in 2003/4, as well as an altered hydrological regime due to increased temperatures and decreased rainfall in that more recent period. The fact that these changes have occurred within the Swan-Canning Estuary highlights the need for effective management tools, such as the habitat classification scheme and associated faunal survey undertaken in this study. Such data will provide a sound basis by which to examine the ways in which fauna vary spatially within the system, and allow for the establishment of comprehensive benchmarks for detecting future changes.

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36

Pratt, Catherine, and n/a. "Investigations into Faecal Sterols and E.Coli as Indicators of Sewage and Non-Sewage Inputs into a Subtropical Estuarine Embayment System in South Eastern QLD, Australia." Griffith University. School of Environmental and Applied Science, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070124.111827.

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Sewage pollution from humans, animal and domestic sources (land and agricultural run-off) are recognized as a major cause of deteriorating water quality along Australia's coastline. Management of water quality has primarily relied on the use of bacterial indicator methods. However the validity and source-specificity of these methods have been met with increasing reservations for several years now. A relatively recent methodology uses a different chemical biomarker approach using 'sterols', a group of compounds related to the common bio-membrane lipid cholesterol and its derivatives. Sterols can offer an additional diagnostic tool to distinguish and discriminate between sources of faecal contamination in marine, freshwater and estuarine environments in both sediments and the water column. This study investigates for the first time, the degradation of coprostanol and selected faecal sterols in 'natural' sediments from a highly mixed (marine and estuarine) sub-tropical environment following a simulated pollution event (primary effluent); the use of faecal sterols as an additional indicator for determining non-point source sewage discharges at popular anchorages in the Moreton Bay and Gold Coast Broadwater system; and the use of sterol ratios in the determination of the fate and transportation of nutrients from a Sewage Treatment Plant (STP) point-source outlet pipe during plant malfunction. The microcosm degradation experiment revealed that faecal and selected sterols are continually synthesised and degraded over time by auto- and hetero trophic organisms within the sediment matrix. Coprostanol was the only sterol to degrade continually, with only minor fluctuations over a time period of two months. Results from this degradation experiment further revealed a sharp decline of coprostanol within the first week. From this it could be concluded that, without any further addition, external inputs of coprostanol are reduced to background levels within this time period. Therefore, removal of coprostanol after six days was 94% and 73% in mud and sand, respectively. The removal of coprostanol was much higher in mud than sand, reflecting a higher level of microbial activity in muddy sediments for assimilation of sterols. The field study undertaken at popular anchorages in Moreton Bay and the Gold Coast Broadwater revealed extremely low levels of sterols and bacterial indicators over both a spatial and temporal scale consistent with a shallow, oligotrophic, highly dynamic sand dominated system. Even though sterols analysed were found at extremely low levels (mostly in the nano-gram range), they were found to be highly correlated and were successful in identifying an unexpected once off pollution event from a point source at Moreton Bay Island. Other than this one incident, both sterol and bacterial levels were consistently low even when anchorages were at full capacity. Thus, sewage from recreational vessels was found to have very little, if any, effect on the water quality at anchorages in Moreton Bay and Gold Coast Broadwater. The point-source study conducted during a local sewage treatment plant malfunction revealed that even though absolute concentrations of sterols did not change during this event, the distribution of sterols within the samples changed, hence changing the sterol ratios. Further, nutrients (mainly nitrogen) can be transported several kilometres by currents, flocculate out of the water column and settle out into the sediment in areas with low tidal and hydrological flushing. There, the nutrients can cause in situ production of sterols in sediments changing sterol ratios. Overall, this study revealed that analyses of sterol biomarkers have the potential to indicate nutrient inputs (such as nitrogen) as well as sewage, post-hoc pollution events at extremely low levels/high dilutions in coastal sediments.

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37

Wildsmith, Michelle. "Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia." Thesis, Wildsmith, Michelle (2007) Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia. PhD thesis, Murdoch University, 2007. https://researchrepository.murdoch.edu.au/id/eprint/424/.

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Анотація:

The following four broad aims were addressed in this study. (1) To ascertain whether the characteristics of the benthic macroinvertebrate assemblages within the different nearshore marine habitat types identified by Valesini et al. (2003) on the lower west coast of Australia differ significantly, and whether the pattern of those spatial differences matches those among the environmental characteristics that were used to distinguish those habitat types; (2) To develop a quantitative approach for classifying nearshore habitats in estuarine waters that employs readily-available data for a range of enduring environmental characteristics, and to use that approach to classify the various habitat types present in nearshore waters of the Swan-Canning Estuary on the lower west coast of Australia; (3) To test the hypothesis that the characteristics of the benthic macroinvertebrate assemblages in the in the Swan-Canning Estuary differ significantly among nearshore habitat types, and that the pattern of those differences matches that among the environmental characteristics used to distinguish those habitat types and (4) To test the hypothesis that, as a result of environmental changes in the Swan-Canning Estuary, the characteristics of the benthic macroinvertebrate assemblages at various habitats in this estuary in 1986/7 differ from those in 2003/4. To address the first aim, benthic macroinvertebrates were sampled seasonally for one year in the subtidal waters and intertidal zone (upper and lower swash zones) at the six nearshore habitat types that were identified by Valesini et al. (2003) on the lower west coast of Australia. The habitat types, which differed mainly in the extent of their exposure to wave activity and whether seagrass and/or nearshore reefs were present, had been distinguished quantitatively using values for a suite of seven statistically-selected enduring environmental characteristics. The faunal samples yielded a total of 121 species representing eight phyla, among which the Polychaeta, Malacostraca and Bivalvia were the most speciose classes and contributed ~ 38, 23 and 10%, respectively, to the total number of individuals. The total number of species and mean density of macroinvertebrates was far greater at the most protected habitat type (1), which also contained dense beds of seagrass, than at any other habitat type, i.e. 70 species and 209.2 individuals 0.1 m-2, compared to 32 species and 36.9 individuals 0.1 m-2 at the most exposed habitat type (6), which had a substrate comprised only of sand. Differences among habitat type influenced the benthic macroinvertebrate species composition to a greater extent than differences among either zones or seasons. Significantly different faunal compositions were detected among those latter two factors only at the most protected habitat type. The faunal assemblage at habitat type 1 was clearly the most distinct from those at the other five habitat types, particularly in the subtidal zone (R-statistics=0.642-0.831, p=0.1%), and was typified by five abundant polychaete species that were adapted to deposit-feeding. In contrast, the fauna at habitat type 6 was typified by four crustacean species and a species of bivalve and polychaete, whose mobility and tough external surface facilitated their survival and feeding in those turbulent waters. The extents of the differences in species composition among the six habitat types was significantly matched with that among the suite of enduring environmental characteristics that distinguished those habitat types, particularly in the case of the subtidal zone (Rho=0.676). Such results indicated that the environmental variables used to distinguish the nearshore habitat types could be used to reliably predict the types of benthic macroinvertebrate species likely to occur at any site along the lower west coast of Australia. The above biological validation of the nearshore marine habitat classification scheme developed by Valesini et al. (2003) provided the justification for the approach to the second broad aim of this study, namely to develop a quantitative scheme for classifying habitat types in the Swan-Canning Estuary. This approach was similar to that employed by Valesini et al. (2003) in that it considers that differences among habitat types are well reflected by differences in a suite of enduring environmental variables. However, it improves on that earlier method by employing a completely objective and quantitative approach. Thus, a large number of environmentally-diverse nearshore sites (102) were initially selected throughout the Swan-Canning Estuary and a suite of 13 enduring environmental variables quantified at each using remotely-sensed images of the estuary in a Geographic Information System. Such variables were chosen to reflect either (i) the type of substrate and submerged vegetation present, (ii) the extent of exposure to wave action or (iii) the location of the site within the estuary with respect to its vicinity to marine and fresh water sources. These data were then subjected to the CLUSTER routine and associated SIMPROF procedure in the PRIMER v6 multivariate statistical package to quantitatively identify those groups of sites that did not differ significantly in their environmental characteristics, and thus represented habitat types. Eighteen habitat types were identified, which were shown to well reflect spatial differences in a suite of non-enduring water quality and sediment characteristics that were measured in situ at a range of estuarine sites during both summer and winter in 2005 (Rho=0.683 and 0.740, respectively, p=0.1%). However, those latter environmental characteristics required far more time in the field and laboratory to quantify than the enduring variables used to identify the habitat types. Benthic macroinvertebrates were sampled during summer and winter in 2005 in the shallow subtidal regions (~1 m depth) at sites representing eight of the habitat types identified in the Swan-Canning Estuary. These samples contained a total of 51 and 36 species during summer and winter, respectively, and, in both seasons, represented nine phyla, namely Annelida, Crustacea, Mollusca, Sipuncula, Nematoda, Platyhelminthes, Cnidaria, Uniramia and Nemertea. The compositions of the benthic macroinvertebrate assemblages differed significantly among habitat types and, to a similar extent, between seasons (Global R-statistic=0.408 and 0.409, respectively, p=0.1%). However, the spatial differences were considerable greater in winter than in summer (Global R-statistic=0.536 vs 0.280, p=0.1%), presumably due to the greater spatial variation in particular non-enduring in situ environmental characteristics, such as redox depth and salinity. While the number of species, overall density and taxonomic distinctness of benthic macroinvertebrates also differed significantly among habitats, those variables differed to a greater extent between seasons, being greater in winter than in summer. While the measures of taxonomic distinctness tended to be greater at habitat types located in the lower to middle reaches, i.e. habitat types 6, 7, 9, 10, 13 and 18, than the upper reaches i.e. habitat types 1 and 3, the number of species and overall density reflected this trend only during winter. During summer, the mean numbers of species at habitat types 1, 3, 6 and 10 (3.4-6.0) were significantly lower than those at habitat types 7, 13, and 18 (8.8-10.9), whereas the overall density of benthic macroinvertebrates was far greater at habitat type 7 (32260 individuals 0.1 m-2)than at any other habitat type in this season (3135-18552 individuals 0.1 m-2). Overall, the greatest differences in assemblage composition occurred between those at habitat types 1 and 18 (R-statistic=0.669, p=0.1%), which were located in the uppermost region of the estuary and the lower reaches of the basin, respectively, and differed to the greatest extent in their enduring environmental characteristics. The assemblage at habitat type 1, and also that at habitat type 3, located just downstream, were relatively distinct from those at all other habitat types, particularly during winter (R-statistics=0.666-0.993, p=0.1%). The fauna at the first of these habitat types was relatively depauperate, containing low numbers of species and densities, and was characterised by the polychaetes Leitoscoloplos normalis and Ceratonereis aequisetis and the bivalve Arthritica semen. The assemblage at habitat type 3 was also characterised by those three species and the amphipod Paracorophium minor and the polychaete Boccardiella limnicola. In contrast, the assemblage at habitat type 18 was characterised by a more diverse assemblage, i.e. the polychaetes Capitella capitata, C. aequisetis, L. normalis and Pseudopolydora kempi, the amphipods, Grandidierella propodentata and Corophium minor and the bivalve Sanguinolaria biradiata. The number of species was among the highest at this habitat type during both seasons, which was also reflected in the high taxonomic diversity, and the overall density was the highest in winter and second highest in summer. Despite the above faunal differences, those between assemblages at habitat types 7 and 9, which were both located in the basin of the Swan-Canning Estuary, were similar in magnitude to those that occurred between pairs of habitat types located in two different regions of the estuary. Although both habitat types 7 and 9 were characterised by a similar suite of species, i.e. Oligochaete spp., C. aequisetis, C. capitata, C. minor, G. propodentata, L. normalis, and S. biradiata, the substantial differences in assemblage composition between these habitat types in both summer and winter (R-statistics=0.570 and 0.725, respectively) was due to marked differences in the relative contributions of each of these species. Significant and strong correlations were shown to exist in both summer and winter between the pattern of differences in the benthic macroinvertebrate assemblages among habitat types and that among the enduring environmental characteristics used to identify those habitat types (Rho=0.625 and 0.825, respectively, p=0.1%). Furthermore, these correlations were greater than those obtained between the benthic macroinvertebrate fauna and any combination of the non-enduring environmental characteristics (i.e. water quality and sediment parameters) recorded in situ at each habitat type (Rho=0.508 and 0.824, in summer and winter, respectively, p=o.1%). This demonstrates the greater capacity of surrogate enduring environmental characteristics to account for differences in the range of variables that may influence the distribution of benthic invertebrate fauna. Thus, the lists of characteristic benthic macroinvertebrate taxa produced for each of the eight habitat types studied in the Swan-Canning Estuary provide a reliable benchmark by which to gauge any future changes in those fauna. Moreover, these results indicate that the above habitat classification scheme can be used to reliably predict the types of benthic macroinvertebrate fauna that are likely to occur at any nearshore site of interest in this estuarine system. The final component of this study showed that the benthic macroinvertebrate assemblages at four sites in the middle reaches of the Swan-Canning Estuary in 2003/4 differed significantly from those recorded at the same sites in 1986/7. Such differences were reflected in (1) changes in the relative densities of a suite of ten species that were responsible for distinguishing the faunas in these two periods, (2) the absence of 22 rare species in 2003/4 (i.e. 42% of the number of species recorded in 1986/7), (3) the presence of 17 new species in 2003/4, including an abundant polychaete that is likely to have been introduced and (4) a far greater extent of seasonal variation in the number of species and densities of benthic macroinvertebrates in 2003/4. Such changes are likely to be related to lower sediment oxygen levels in certain seasons in 2003/4, as well as an altered hydrological regime due to increased temperatures and decreased rainfall in that more recent period. The fact that these changes have occurred within the Swan-Canning Estuary highlights the need for effective management tools, such as the habitat classification scheme and associated faunal survey undertaken in this study. Such data will provide a sound basis by which to examine the ways in which fauna vary spatially within the system, and allow for the establishment of comprehensive benchmarks for detecting future changes.

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38

Wildsmith, Michelle. "Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia." Wildsmith, Michelle (2007) Relationships between benthic macroinvertebrate assemblages and habitat types in nearshore marine and estuarine waters along the lower west coast of Australia. PhD thesis, Murdoch University, 2007. http://researchrepository.murdoch.edu.au/424/.

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Анотація:

The following four broad aims were addressed in this study. (1) To ascertain whether the characteristics of the benthic macroinvertebrate assemblages within the different nearshore marine habitat types identified by Valesini et al. (2003) on the lower west coast of Australia differ significantly, and whether the pattern of those spatial differences matches those among the environmental characteristics that were used to distinguish those habitat types; (2) To develop a quantitative approach for classifying nearshore habitats in estuarine waters that employs readily-available data for a range of enduring environmental characteristics, and to use that approach to classify the various habitat types present in nearshore waters of the Swan-Canning Estuary on the lower west coast of Australia; (3) To test the hypothesis that the characteristics of the benthic macroinvertebrate assemblages in the in the Swan-Canning Estuary differ significantly among nearshore habitat types, and that the pattern of those differences matches that among the environmental characteristics used to distinguish those habitat types and (4) To test the hypothesis that, as a result of environmental changes in the Swan-Canning Estuary, the characteristics of the benthic macroinvertebrate assemblages at various habitats in this estuary in 1986/7 differ from those in 2003/4. To address the first aim, benthic macroinvertebrates were sampled seasonally for one year in the subtidal waters and intertidal zone (upper and lower swash zones) at the six nearshore habitat types that were identified by Valesini et al. (2003) on the lower west coast of Australia. The habitat types, which differed mainly in the extent of their exposure to wave activity and whether seagrass and/or nearshore reefs were present, had been distinguished quantitatively using values for a suite of seven statistically-selected enduring environmental characteristics. The faunal samples yielded a total of 121 species representing eight phyla, among which the Polychaeta, Malacostraca and Bivalvia were the most speciose classes and contributed ~ 38, 23 and 10%, respectively, to the total number of individuals. The total number of species and mean density of macroinvertebrates was far greater at the most protected habitat type (1), which also contained dense beds of seagrass, than at any other habitat type, i.e. 70 species and 209.2 individuals 0.1 m-2, compared to 32 species and 36.9 individuals 0.1 m-2 at the most exposed habitat type (6), which had a substrate comprised only of sand. Differences among habitat type influenced the benthic macroinvertebrate species composition to a greater extent than differences among either zones or seasons. Significantly different faunal compositions were detected among those latter two factors only at the most protected habitat type. The faunal assemblage at habitat type 1 was clearly the most distinct from those at the other five habitat types, particularly in the subtidal zone (R-statistics=0.642-0.831, p=0.1%), and was typified by five abundant polychaete species that were adapted to deposit-feeding. In contrast, the fauna at habitat type 6 was typified by four crustacean species and a species of bivalve and polychaete, whose mobility and tough external surface facilitated their survival and feeding in those turbulent waters. The extents of the differences in species composition among the six habitat types was significantly matched with that among the suite of enduring environmental characteristics that distinguished those habitat types, particularly in the case of the subtidal zone (Rho=0.676). Such results indicated that the environmental variables used to distinguish the nearshore habitat types could be used to reliably predict the types of benthic macroinvertebrate species likely to occur at any site along the lower west coast of Australia. The above biological validation of the nearshore marine habitat classification scheme developed by Valesini et al. (2003) provided the justification for the approach to the second broad aim of this study, namely to develop a quantitative scheme for classifying habitat types in the Swan-Canning Estuary. This approach was similar to that employed by Valesini et al. (2003) in that it considers that differences among habitat types are well reflected by differences in a suite of enduring environmental variables. However, it improves on that earlier method by employing a completely objective and quantitative approach. Thus, a large number of environmentally-diverse nearshore sites (102) were initially selected throughout the Swan-Canning Estuary and a suite of 13 enduring environmental variables quantified at each using remotely-sensed images of the estuary in a Geographic Information System. Such variables were chosen to reflect either (i) the type of substrate and submerged vegetation present, (ii) the extent of exposure to wave action or (iii) the location of the site within the estuary with respect to its vicinity to marine and fresh water sources. These data were then subjected to the CLUSTER routine and associated SIMPROF procedure in the PRIMER v6 multivariate statistical package to quantitatively identify those groups of sites that did not differ significantly in their environmental characteristics, and thus represented habitat types. Eighteen habitat types were identified, which were shown to well reflect spatial differences in a suite of non-enduring water quality and sediment characteristics that were measured in situ at a range of estuarine sites during both summer and winter in 2005 (Rho=0.683 and 0.740, respectively, p=0.1%). However, those latter environmental characteristics required far more time in the field and laboratory to quantify than the enduring variables used to identify the habitat types. Benthic macroinvertebrates were sampled during summer and winter in 2005 in the shallow subtidal regions (~1 m depth) at sites representing eight of the habitat types identified in the Swan-Canning Estuary. These samples contained a total of 51 and 36 species during summer and winter, respectively, and, in both seasons, represented nine phyla, namely Annelida, Crustacea, Mollusca, Sipuncula, Nematoda, Platyhelminthes, Cnidaria, Uniramia and Nemertea. The compositions of the benthic macroinvertebrate assemblages differed significantly among habitat types and, to a similar extent, between seasons (Global R-statistic=0.408 and 0.409, respectively, p=0.1%). However, the spatial differences were considerable greater in winter than in summer (Global R-statistic=0.536 vs 0.280, p=0.1%), presumably due to the greater spatial variation in particular non-enduring in situ environmental characteristics, such as redox depth and salinity. While the number of species, overall density and taxonomic distinctness of benthic macroinvertebrates also differed significantly among habitats, those variables differed to a greater extent between seasons, being greater in winter than in summer. While the measures of taxonomic distinctness tended to be greater at habitat types located in the lower to middle reaches, i.e. habitat types 6, 7, 9, 10, 13 and 18, than the upper reaches i.e. habitat types 1 and 3, the number of species and overall density reflected this trend only during winter. During summer, the mean numbers of species at habitat types 1, 3, 6 and 10 (3.4-6.0) were significantly lower than those at habitat types 7, 13, and 18 (8.8-10.9), whereas the overall density of benthic macroinvertebrates was far greater at habitat type 7 (32260 individuals 0.1 m-2)than at any other habitat type in this season (3135-18552 individuals 0.1 m-2). Overall, the greatest differences in assemblage composition occurred between those at habitat types 1 and 18 (R-statistic=0.669, p=0.1%), which were located in the uppermost region of the estuary and the lower reaches of the basin, respectively, and differed to the greatest extent in their enduring environmental characteristics. The assemblage at habitat type 1, and also that at habitat type 3, located just downstream, were relatively distinct from those at all other habitat types, particularly during winter (R-statistics=0.666-0.993, p=0.1%). The fauna at the first of these habitat types was relatively depauperate, containing low numbers of species and densities, and was characterised by the polychaetes Leitoscoloplos normalis and Ceratonereis aequisetis and the bivalve Arthritica semen. The assemblage at habitat type 3 was also characterised by those three species and the amphipod Paracorophium minor and the polychaete Boccardiella limnicola. In contrast, the assemblage at habitat type 18 was characterised by a more diverse assemblage, i.e. the polychaetes Capitella capitata, C. aequisetis, L. normalis and Pseudopolydora kempi, the amphipods, Grandidierella propodentata and Corophium minor and the bivalve Sanguinolaria biradiata. The number of species was among the highest at this habitat type during both seasons, which was also reflected in the high taxonomic diversity, and the overall density was the highest in winter and second highest in summer. Despite the above faunal differences, those between assemblages at habitat types 7 and 9, which were both located in the basin of the Swan-Canning Estuary, were similar in magnitude to those that occurred between pairs of habitat types located in two different regions of the estuary. Although both habitat types 7 and 9 were characterised by a similar suite of species, i.e. Oligochaete spp., C. aequisetis, C. capitata, C. minor, G. propodentata, L. normalis, and S. biradiata, the substantial differences in assemblage composition between these habitat types in both summer and winter (R-statistics=0.570 and 0.725, respectively) was due to marked differences in the relative contributions of each of these species. Significant and strong correlations were shown to exist in both summer and winter between the pattern of differences in the benthic macroinvertebrate assemblages among habitat types and that among the enduring environmental characteristics used to identify those habitat types (Rho=0.625 and 0.825, respectively, p=0.1%). Furthermore, these correlations were greater than those obtained between the benthic macroinvertebrate fauna and any combination of the non-enduring environmental characteristics (i.e. water quality and sediment parameters) recorded in situ at each habitat type (Rho=0.508 and 0.824, in summer and winter, respectively, p=o.1%). This demonstrates the greater capacity of surrogate enduring environmental characteristics to account for differences in the range of variables that may influence the distribution of benthic invertebrate fauna. Thus, the lists of characteristic benthic macroinvertebrate taxa produced for each of the eight habitat types studied in the Swan-Canning Estuary provide a reliable benchmark by which to gauge any future changes in those fauna. Moreover, these results indicate that the above habitat classification scheme can be used to reliably predict the types of benthic macroinvertebrate fauna that are likely to occur at any nearshore site of interest in this estuarine system. The final component of this study showed that the benthic macroinvertebrate assemblages at four sites in the middle reaches of the Swan-Canning Estuary in 2003/4 differed significantly from those recorded at the same sites in 1986/7. Such differences were reflected in (1) changes in the relative densities of a suite of ten species that were responsible for distinguishing the faunas in these two periods, (2) the absence of 22 rare species in 2003/4 (i.e. 42% of the number of species recorded in 1986/7), (3) the presence of 17 new species in 2003/4, including an abundant polychaete that is likely to have been introduced and (4) a far greater extent of seasonal variation in the number of species and densities of benthic macroinvertebrates in 2003/4. Such changes are likely to be related to lower sediment oxygen levels in certain seasons in 2003/4, as well as an altered hydrological regime due to increased temperatures and decreased rainfall in that more recent period. The fact that these changes have occurred within the Swan-Canning Estuary highlights the need for effective management tools, such as the habitat classification scheme and associated faunal survey undertaken in this study. Such data will provide a sound basis by which to examine the ways in which fauna vary spatially within the system, and allow for the establishment of comprehensive benchmarks for detecting future changes.

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39

Lenanton, Rodney Charles John. "The role of estuarine and inshore-marine environments in the life cycles of the exploited marine fish species of temperate Western Australia." Thesis, Lenanton, Rodney Charles John (1988) The role of estuarine and inshore-marine environments in the life cycles of the exploited marine fish species of temperate Western Australia. PhD thesis, Murdoch University, 1988. https://researchrepository.murdoch.edu.au/id/eprint/50320/.

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The way in which "estuarine-dependent" fish use selected permanently open, seasonally open, and normally closed estuaries, and inshore marine waters is discussed. Attention is initially focused on the impact of reducing the connection between the sea in those estuaries in which bars tend to form at their mouths, and the effect of the resultant fluctuations in salinity on the composition and abundance of the estuarine fish community. Many of the commercially important and alleged "estuarine-dependent" marine species utilise nearshore marine habitats as an alternative to those provided by estuaries, even when a bar does not prevent access to the estuary. Many of these nearshore marine habitats, particularly the surf-zone, often harbour large accumulations of detached macrophyte detritus. Most of the fish caught in the surf-zone were represented by juveniles, and a number were important commercial species that were also abundant in estuaries. The total number of fish was strongly correlated with the amount of detached macrophytes present. The dominant species caught fell into two groups, i.e. those that were equally abundant in weeded and non-weeded surf-zones, and those that were almost exclusively found in weed. Dietary analyses of fish, allied with the large numbers of pisciverous cormorants present, show that the weed in the surf-zone provides a rich feeding site and suggests that it is a refuge from diurnal predation. The number of the commercially important Cnidoglanis macroceQhalus (mainly O+) was positively correlated with both the volume of fine red algae and dead seagrass. These respective two components of the drift have been shown to provide a habitat and food supply for the amphipod Allochestes comQressa, which is a major food item of the surf-zone populations of C.macrQQeQhalus. The contribution of the weight and value of "estuarine-dependent" finfish species to the total commercial fishery of temperate Western Australia was shown to be 20.3 and 2.4% respectively. Since many "alleged" "estuarine-dependent" species also use protected inshore marine waters as nursery areas in both south-western Australia and in other regions of temperate Western Australia where estuaries are absent, these species cannot be considered to be entirely dependent on estuaries. It is therefore preferable to regard these species as "estuarine-opportunists".

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40

Laurenson, Laurie Jon Bain. "Biology and commercial exploitation of the estuarine catfish, Cnidoglanis macrocephalus (Valenciennes) in South Western Australia with emphasis on the seasonally closed Wilson Inlet." Thesis, Laurenson, Laurie Jon Bain (1992) Biology and commercial exploitation of the estuarine catfish, Cnidoglanis macrocephalus (Valenciennes) in South Western Australia with emphasis on the seasonally closed Wilson Inlet. PhD thesis, Murdoch University, 1992. https://researchrepository.murdoch.edu.au/id/eprint/52064/.

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Wilson Inlet is a seasonally closed estuary on the southern coast of Western Australia. It comprises a large basin (48 km^2), which is fed by two main tributary rivers and opens to the ocean by a narrow 1 km inlet channel. The sand bar which forms across the mouth of the estuary during dry periods is artificially breached when water levels reach 1.015 m Australian Height Datum. The length of time the estuary is open to the sea, which ranges from about two to 11 months, is related to the time of opening, i.e. the earlier the opening (which corresponds to high winter fresh water build up), the longer the bar remains breached. Samples of the estuarine catfish Cnidoglanis macrocephalus were collected by gill net and beach seines from the basin of Wilson Inlet in each month between September 1987 and April 1989. Cnidoglanis macrocephalus is a benthic carnivore, feeding mainly on molluscs, crustaceans and polychaetes. Diet changed from soft bodied prey {e.g. crustaceans, mytilids, nereids and gastropods) to robust bivalves {e.g. tellinids and venerids) with increasing body size and it also changed with season. Spawning occurred within the estuary, predominantly between mid-spring (October) and mid-summer (January), with peak spawning activity late November and early December. Sexual maturity was typically first reached at an average total length of 425 mm, at which size the fish were nearing the end of the third year of life. The eggs of C. macrocephalus were deposited in burrows and the males subsequently guarded both the eggs and larvae. While the growth of C. macrocephalus in Wilson Inlet was more rapid than in a nearby inshore marine area, it was similar to that in the Swan Estuary on the lower west coast of Western Australia further to the north. Commercial catches of C. macrocephalus in Wilson Inlet rose markedly from an annual average of 34,89 kg between 1976 and 1979 to 58,431 kg between 1985 and 1989. During these two periods, the percentage contribution of C. macrocephalus catches in Wilson Inlet to the total catch of this species in Western Australia increased from 15.6 to 46.0%. Commercial catches in Wilson Inlet varied seasonally, being greatest in spring and autumn and lowest during winter. They also varied markedly among years, with values being high in 1975 and 1986 (60,000 to 80,000 kg) and low between 1977 and 1983 (<35,000 kg). The total lengths and numbers of C. macrocephalus caught in the closed and open fishing waters of Wilson Inlet, using a gill net comprising a wide range of mesh sizes, were recorded. These data were then compared with those obtained for the commercial fishery. The results strongly indicate that (I) the density and percentage contribution of large fish are lower in open than in closed fishing waters, (II) female fish were more readily caught than male fish and (III) the minimum legal mesh size and minimum legal length for C. macrocephalus should be increased to prevent fish being caught before they reached sexual maturity.

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41

De, Roach Robert John. "The polychaetes Australonereis ehlersi (Augener) and Simplisetia aequisetis (Augener) within the eutrophic Swan river estuary, Western Australia : life history, population structure and effects on sedimentary microbial nitrogen cycling." University of Western Australia. Dept. of Zoology, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0006.

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[Truncated abstract] In my study of Australonereis ehlersi and Simplisetia aequisetis [Polychaeta: Nereididae] from the Swan River Estuary, Western Australia, I assessed the life history, geographical population structure and production of both species, then measured their roles in microbial denitrification and nitrogen cycling within the sediments of the estuary. Both species exhibit a mean life-span of approximately 1 year, a production:biomass turnover rate of about 3 and potentially are capable of reproducing throughout the year, peaking during winter to spring. A. ehlersi exhibited a marine euryhaline distribution, occurring only in the main basin and lower estuary, typically at a very low density of adults; S. aequisetis exhibited a euryhaline distribution, occurring estuary-wide during both summer and winter. High density and biomass of A. ehlersi occurred in the middle estuary (at Como), predominantly as winter- recruiting juveniles. Gravid, atokous adults spawned pelagically, with a 2 to 4 month larval development period preceding settlement. Intolerance of freshwater by the pelagic larvae possibly is the major reason excluding specimens from the upper reaches of the Estuary. Adult S. aequisetis brood eggs and embryonic larvae in tubiculous burrows; the life-cycle presumably progresses entirely in sediments of relatively stable interstitial salinity (compared to pelagic fluctuations), enabling recruitment by larvae and adults into the upper reaches of the Estuary. ... The ammonification rate was higher for A. ehlersi than S. aequisetis-inhabited cores, and lowest in uninhabited cores where polychaete excretion was absent. In the absence of C2H2, sediments of S. aequisetis inhabited cores indicated a lower net NH4+ influx than uninhabited cores, whereas A. ehlersi inhabited cores exhibited a slight net efflux of NH4+ from the sediment. The difference in magnitude of nitrogenous fluxes imparted by the two polychaete species is hypothesised to relate to the influence of their respective habits on the composition and activity of their associated sedimentary microbial community. Juvenile S. aequisetis are hypothesised to homogenise and aerate sediment continually, enhancing microbial nitrification and retarding anaerobic denitrification. Permanent A. ehlersi burrows would facilitate vertical and radial oxic/anoxic stratification of sediment which, combined with enhanced substrate supply through burrow ventilation, resulted in increased rates of microbial denitrification and nitrification. I have proposed a preliminary framework by which guilds of benthic fauna, each with similar designated habits, may be tested for predictable bioturbative influence on nitrogen cycling, i.e. whether particular habits may be considered 'functional groups'. In conclusion, the fine-scale effects of A. ehlersi and S. aequisetis on microbial nitrogen cycling are integrated with details of broader-scale population dynamics to define the role of polychaetes in estuarine nitrogen cycling, with a view to managing eutrophication.

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42

Chan, Terence. "Phytoplankton dynamics in a seasonal estuary." University of Western Australia. Centre for Water Research, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0089.

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[Truncated abstract] The Swan River is a highly seasonal estuary in the south-west of Western Australia. Salinity may vary from fresh to marine at various times throughout the estuary, depending mostly on the intensity of freshwater discharge. There are occasional problematic dinoflagellate blooms which have spurred investigation of the dynamics of the phytoplankton community. The objective of this research was to examine how phytoplankton biomass and species' successions are influenced by the multiple variables in the aquatic ecosystem, and, if possible, to determine the dominant factors ... Comparisons of phytoplankton nutrient limitation simulations with experimental observations from field bioassays require further investigation, but reinforce findings that nutrients may only limit phytoplankton biomass when there is a convergence of favourable hydrological and hydrodynamic conditions. The Swan River estuary has undergone substantial hydrological modifications from pre-European settlement. Land clearing has increased freshwater discharge up to 5- fold, while weirs and reservoirs for water supply have mitigated this increase and reduced the duration of discharge to the estuary. Nutrient loads have increased approximately 20-fold from pre-European levels. The individual and collective impacts of these hydrological changes on the Swan River estuary were examined using the hydrodynamic-ecological numerical model. The simulation results indicate that despite increased hydraulic flushing and reduced residence times, increases in nutrient loads are the dominant perturbation, producing increases in the frequency and biomass of blooms by both estuarine and freshwater phytoplankton. By comparison, changes in salinity associated with altered seasonal freshwater discharge have a limited impact on phytoplankton dynamics. Reductions of nutrient inputs into the Swan River estuary from its catchment will provide a long-term improvement in water quality but manipulations of freshwater discharge have the potential to provide a provisional short-term remediation measure allowing at least partial control of phytoplankton bloom potential and eutrophication.

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43

Martin, Carol Linda. "Cultural ecosystem services derived from estuaries in New South Wales, Australia." Thesis, 2019. http://hdl.handle.net/1959.13/1407925.

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Research Doctorate - Doctor of Philosophy (PhD)
Cultural ecosystem services (CES) are the non-material benefits obtained from natural ecosystems that contribute to human wellbeing through aesthetic and recreational experiences, and spiritual enrichment. Research on CES is rapidly increasing with growing recognition of their important contributions to human wellbeing, however, little is known about CES derived from estuaries, some of the most highly impacted and modified ecosystems in the world. Difficulties valuing intangible and subjective attributes of CES, means these ecosystem services cannot be compared with economic-dominated values primarily used in decision-making. This risks a lack of recognition and consideration of CES by decision-makers that compromises the provision of CES and important non-material benefits to human wellbeing. The overall aim of this thesis is to address the knowledge gap on CES derived from estuaries, and explore social-ecological relationships in these areas. Data were collected from people residing near estuaries in New South Wales, Australia, using mixed methods including participatory mapping, personal interviews, focus groups, and an online survey questionnaire. Both quantitative and qualitative data analyses were performed. Key findings revealed estuaries are greatly valued for a range of CES, especially for aesthetic, recreational, nature/biodiversity, and intrinsic/existence/future CES-related values. Certain land use zones and land cover are major providers of specific CES, as well as bundles of CES. Both natural and manmade attributes were considered important for the continued enjoyment and recreational use of estuaries. However, natural attributes were found to be a significant predictor of CES, which in turn was a significant predictor of perceived wellbeing; emphasising the importance of the natural environment in the provision of CES. This is further supported by participants’ concerns about development, pollution and poor water quality having the greatest potential to adversely affect the provision of CES. Additionally, findings provided insights into the nature of non-material benefits supplied by CES in estuarine areas. It was evident participants’ individual and collective experiences provided important restorative, spiritual and relational benefits, but perceptions of development and over-crowding created a sense of solastalgia that impinged on wellbeing. Based on the research findings, a conceptual diagram was developed that can act as a framework to assist in understanding the flow of CES-related benefits obtained from estuarine areas and their influence on wellbeing. It is vital CES are recognised and integrated into governance, and a social-ecological approach to policy development, spatial planning and estuary management is required to promote community wellbeing. Failure to do so will result in the loss and degradation of CES, impacting overall wellbeing, resulting in increased prevalence and associated costs physical and mental health disorders. While spatial mapping of CES offers a viable alternative to economic assessments of CES, it may be useful to explore how contingent valuation methods could help facilitate the inclusion of CES into governance. This would ensure proper recognition of these valuable ecosystem services. Thus, it is necessary to investigate ways of valuing CES in monetary terms through interdisciplinary and participatory research, as well as collaboration with policy makers, spatial planners and resource managers.

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Sheaves, Marcus John. "Estuaries as juvenile habitats for lutjanid and serranid fishes in tropical northeastern Australia." Thesis, 1995. https://researchonline.jcu.edu.au/24125/1/01front.pdf.

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A number of lutjanid and serranid fishes are thought to utilise tropical estuaries as juvenile habitats. However, little detailed biological or life-history information exists for any species, and the species compositions of these families inhabiting tropical estuaries, are poorly known. During this study, the species compositions and life-histories of lutjanid and serranid fishes inhabiting estuaries along the north-eastern coast of tropical Australia were investigated. Using fish-traps, estuary faunas were compared to those inhabiting near-shore reefs. Additional samples were donated by anglers and collected from estuaries by angling. The reproductive statuses, and size and age structures of two serranids (Epinephelus coioides and E. malabaricus) and two lutjanids (Lutjanus russelli and L. argentimaculatus), in estuaries were compared to those of the same species from offshore. Fish-traps were also used to obtain data on the distribution and abundance by size of L. russelli, E. coioides and E. malabaricus from three estuaries - Cattle, Barramundi and Alligator Creeks - over a two year period. Far fewer species of lutjanids and serranids were trapped from estuaries than from nearshore reefs. While fish-trap and angling collections from estuaries produced 9 species of serranids and 5 species of lutjanids, most were collected in low numbers. Only two serranids (Epinephelus coioides and E. malabaricus) and two lutjanids (Lutjanus russelli and L. argentimaculatus) were common in either trap or angling catches. All fish of each of these species from estuaries were found to be much smaller and younger than the largest and oldest fishes of these species from offshore waters. Furthermore, all fish of each species from estuaries were found to be in pre-reproductive condition. This implies that the estuarine populations of these species consist of juveniles, and that they undergo migrations to offshore adult habitats. Thus they possess three distinct life-history stages (pelagic larvae, estuarine juveniles, offshore adults) that correspond to major habitat shifts. L. russelli were common in all estuaries and distributed throughout the three estuaries studied in detail. The probability of capturing L. russelli was similar in seaward areas of Cattle, Barramundi and Alligator Creeks, remained similar upstream areas of Barramundi Creek, but fell markedly in upstream parts of Cattle Creek. Spatial differences in the size of L. russelli (both within and between estuaries) were small, however, there was a strong pattern of seasonal change in the size of L. russelli in all estuaries. This seasonal pattern was apparently a product of the interaction between recruitment, mortality and migration. Studies in Alligator Creek showed that L. russelli demonstrated a strong preference for structurally complex habitats provided by fallen timbers and mangrove roots. The numbers of both species of Epinephelus in trap catches declined in upstream areas of the three estuaries considered in detail. However, this reduction was much more marked for E. coioides than E. malabaricus, and while in downstream areas, the numbers of E. coioides were similar to or greater than those of E. malabaricus, in upstream areas E. malabaricus dominated. This suggests that the two species differ in their abilities to access or remain in upstream areas of estuaries. There was a strong negative correlation between the maximum deviation of salinity from 'normal' seawater levels and catches of both species of Epinephelus, suggesting that long-term salinity variation may be important in determining the distribution and abundance of Epinephelus spp. within estuaries. The occupation of specific habitats during particular periods of development must be considered in the development of management strategies for these fishes. The use of estuaries as juvenile nursery grounds underlines the importance of maintaining the quality of estuarine habitats. More data from localities further afield (both within Australia and overseas) are needed to determine if the reproductive patterns found here apply to these species in other areas or to related species.

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Hitchcock, JN. "Freshwater inflows to estuaries : organic carbon and microbial food webs in south-east Australia." Thesis, 2015. http://hdl.handle.net/10453/35942.

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University of Technology, Sydney. Faculty of Science.
Freshwater inflows (FWI) play a crucial role in maintaining estuarine processes and productivity. River regulation and extraction have greatly reduced FWI to estuaries. Little attention has been paid to the role FWI has in delivering organic carbon to estuaries. The aim of this thesis was to define the relationship between freshwater inflows, organic carbon, bacteria and zooplankton dynamics. To do this, I performed a series of monitoring and experimental studies on the Bega and Clyde River estuaries, Australia. Discharge on both rivers was highly episodic during the study. On the Bega and Clyde Rivers, increasing dissolved organic carbon (DOC) concentrations were closely coupled with increasing discharge. The bioavailability of DOC increased during FWI events, and in turn bacterial growth rates were also higher during and immediately following inflow events. Bacterial growth was carbon limited most of the time, though during high flows, bacteria often became phosphorus limited. Changing availability of DOC and phosphorus during inflow events was the main reason for shifting resource limitation. On both rivers bacterial biomass was positively related to increasing DOC and phosphorus concentrations. Highly episodic discharge during this study had a major structuring role over carbon and bacteria dynamics. On the Bega River I found strong evidence that allochthonous carbon and bacteria can subsidise zooplankton production following the input of DOC during FWI events. Zooplankton density increased following a flooding event on the Bega River and stable isotope analysis indicated allochthonous terrestrial carbon was the dominant source of carbon utilised by zooplankton. Experimental mesocosms confirmed that allochthonous carbon and bacteria can support increased zooplankton in the presence of high subsidies. The individual studies forming this thesis all contribute new insights to their respective sub-disciplines within aquatic ecology. Viewed together, they present a novel conceptualisation of hydrology and freshwater inflows in the coastal carbon cycle and microbial food webs in south-east Australian estuaries. The results provide a strong case to protect freshwater inflows to estuaries.

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McPhee, Jack J. "Life history characteristics of glassfish, Ambassis jacksoniensis, adjacent to saltmarsh within a large and permanently-open estuary." Thesis, 2017. http://hdl.handle.net/1959.13/1343123.

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Research Doctorate - Doctor of Philosophy (PhD)
Saltmarsh vegetation, which typically occurs in intertidal areas within estuaries globally, provides an important habitat and feeding ground for estuarine organisms such as crustaceans, gastropods, birds and fish (some of which are of economic importance). Within south-east Australian estuaries, saltmarsh vegetation is both typically bordered by mangroves and tidally inundated three or four times per month during the high tide of the spring tidal cycle (during the day high tide in summer and during the night high tide in winter). In recent decades, saltmarsh vegetation has declined globally due to anthropogenic influence, and in Australia, ‘Coastal Saltmarsh’ is now listed as an Endangered Ecological Community under the Threatened Species Conservation Act 1995. This study was conducted within a representative and relatively “unmodified” saltmarsh habitat (Empire Bay Wetland) in a large and permanently open estuary, Brisbane Water Estuary, located in south-eastern Australia. This study, which was conducted at two markedly different times of the year during 2012, examined the general “response” of the estuarine fish (using seine nets) and zooplankton (using plankton nets) assemblages to tidal inundation, with further emphasis being placed on selected biological and ecological characteristics of the abundant estuarine ambassid, Ambassis jacksoniensis. Abundances of A. jacksoniensis (mean standard length=37.3 mm, ±0.021 (SE)) and overall fish diversity were greater in nightly winter catches than daily summer catches, which is consistent with previous evidence of important feeding times for estuarine fish (including A. jacksoniensis) upon saltmarsh derived zooplankton (e.g. crab zoeae released by saltmarsh-dwelling grapsid crabs), during ebb tides that drain saltmarsh following its inundation. Indeed, zooplankton assemblages were dominated by crab zoeae during ebb tides following saltmarsh inundation, while calanoid copepods dominated these assemblages at other times. Moreover, stomach content analyses of A. jacksoniensis showed that crab zoeae were heavily preyed upon during such times, with dietary “switching” to caridean decapods being evident when crab zoeae were not abundantly present within the water column (i.e. during flood tides and during ebb tides that did not follow saltmarsh inundation; as shown within zooplankton assemblages). Despite their high abundance within zooplankton assemblages, calanoid copepods were not preyed upon by A. jacksoniensis, which is likely to reflect the relatively fast escape responses of calanoids to predators. Further, stomach fullnesses of A. jacksoniensis were generally highest during ebb tides on days of saltmarsh inundation, implying that feeding was most marked at these times. Trophic relay is an ecological model that involves the movement of biomass and energy from vegetation, such as saltmarshes, within estuaries to the open sea via a series of predator-prey relationships. Therefore, the trophic relationship between saltmarsh-dwelling grapsid crabs (which feed on saltmarsh-derived detritus and microphytobenthos), A. jacksoniensis and their predators (which include economically important fish, such as Acanthopagrus australis, Platycephalus fuscus and Argyrosomus japonicus, provides evidence of partial trophic relay within this system, and thus highlights the ecological and economic importance of saltmarsh within this system. The trophic relationship between A. jacksoniensis and its zooplanktonic prey (e.g. crab zoeae, which is of a red/orange colour) was further investigated, for the first time, by comparisons of the calorimetric contribution of its potential prey (i.e. crab zoeae, and the far paler caridean decapods and calanoid copepods), which found no difference in the energetic densities among such potential prey, suggesting that prey (i.e. zooplankton) abundance and/or prey visibility (due to colour) has a stronger relationship than prey energetic density to the diets of A. jacksoniensis. The feeding ecology of A. jacksonsiensis was also explored, for the first time, in light of its various life history characteristics (e.g. the seasonality of sex ratios, sexual maturity and somatic/reproductive growth), with links being made between saltmarsh-derived tropic relay and energetic requirements for reproductive purposes. Thus, the gonads of A. jacksoniensis were found to be generally maturing and ripe during summer, while juvenile/inactive and spent gonads were prevalent during winter, consistent with previous evidence that A. jacksoniensis spawn during summer with a lull during winter. The sex ratios of A. jacksoniensis were also heavily female-biased during summer before equalising (to approximately 1:1) during winter, suggesting that male A. jacksoniensis may avoid the shallow sampling locations (seagrass adjacent to the saltmarsh/mangroves) in a strategy to counteract visual predation from fish and birds during daytime (summer) before returning to these waters during the night winter, during a lull in spawning, for important feeding opportunities. Female A. jacksoniensis, alternatively, may remain in such vulnerable locations due to increased energetic requirements for reproductive purposes (as demonstrated in male vs female somatic/gonadal growth analyses). These findings therefore suggest that the seasonal timing of spawning for A. jacksoniensis may be linked to their feeding behaviours (i.e. upon saltmarsh-derived zooplankton), the latter of which is governed by the tidal inundation of saltmarsh vegetation. As there is a global ecological and economic reliance by fish (particularly A. jacksoniensis) on saltmarshes, which facilitate trophic relay within these systems, it is imperative that management of Australian estuaries is employed in a manner that appropriately incorporates the conservation of saltmarsh vegetation and thus protects its ecological function within these estuaries.

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Fries, Jakob. "Measuring productivity of Australian tropical estuaries using standing stock analysis." Thesis, 2019. https://researchonline.jcu.edu.au/65063/1/JCU_65063_Fries_2019_thesis.pdf.

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Jakob Fries investigated the reliability of an alternative approach to fisheries productivity measurement in tropical estuarine ecosystems. His studies found that the assumptions length-based growth estimation methods were not biologically reasonable, and multivariate ordination techniques were potentially unreliable. The results of this study are important for industry practices.

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Nelson, Peter. "Ecological studies in the restoration of estuarine wetland habitats in Eastern Australia." Thesis, 2006. http://hdl.handle.net/1959.13/1312838.

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Research Doctorate - Doctor of Philosophy (PhD)
There is worldwide recognition that extensive loss and degradation of habitat in estuarine wetlands has occurred as a result of human activities. This has led to environmental and economic concerns which have results in increasing social pressure to conserve remaining sites and to actively rehabilitate and restore estuarine wetlands are being realised. This study reports on research aspects of two large estuarine rehabilitation projects; the Kooragang Island Wetland Rehabilitation Project in the Hunter River Estuary on the central coast (151°E, 33°S) and the Yarrahapinni Wetland Rehabilitation Project in the Macleay River Estuary (153°E, 31°S) on the mid north coast of New South Wales, Australia. The aims of the two projects shared similarities, but the estuaries differed substantially in their hydrology and geomorphology and they had different recent histories with the Hunter Estuary being highly developed for industry and settlement, and the Macleay Estuary remaining largely rural. A primary objective of the research was to measure change in selected environmental parameters in order to gauge the success, reported here, in restoring 'healthy' estuarine wetlands. This improvement in ecosystem health would be achieved by restoring natural tidal flows by opening the floodgates at Yarrahapinni and replacing restrictive culverts at Kooragang which have for decades isolated the wetlands from the natural estuarine tidal influences. Scientific experiments and empirical observations were designed to test the general hypothesis that reinstatement of tidal influence in the wetlands would result in changes in the biotic and abiotic parameters that would in substantial measure then become similar to their former state. The studies examined water quality and estuarine organisms in order to gauge the relationships between the parameters and the ecological health of the biotic communities. Comparisons were made between the biological communities in the degraded wetlands and nearby estuarine sites designated as controls, which were assumed to be similar to the endpoint of proposed restoration efforts. A 'successful' rehabilitation of the wetland would be indicated by similarity to the control sites. The dataset gathered fro the wetland and the comparative sites in the Macleay River Estuary became a long term examination of spatial and temporal change which allowed a rare opportunity to monitor estuarine and degraded wetland biotic and abiotic parameters over an extended period. Measurements were made on selected water quality parameters, cover of wetland plant species, benthic macroinvertebrate species abundance and waterbird species abundance. The study confirms that prior to the impoundment of the Yarrahapinni Wetland the dominant estuarine vegetation communities were mangrove, saltmarsh and possibly seagrass. When the study commenced there were only small remnants of the once very extensive areas of these estuarine communities in the impounded wetland. Comparisons of historical aerial photography documented the existence of around 200 hectares of mangrove and more than 230ha of saltmarsh in the wetland prior to impoundment. Greater than 99% of the area of these estuarine vegetation communities were lost following impoundment with a consequent loss of habitat for the dependent fauna. The Hunter River study involved the investigation of change in the vegetation communities on five Kooragang Island tidal creek floodplains. The two creeks where tidal flows were to be restored were designated as experimental sites, and the three creeks where flows were not to be restored, as controls. The experimental design was modified, however, when removal of restrictions to tidal flows on one of the experimental creeks caused flooding into the adjacent control creek. Vegetation communities changed in the tidal creek floodplains in response to the altered tidal regimes, whilst the control creek vegetation remained largely unchanged over five years. A large experimental plot was constructed to determine whether saltmarsh on excavated upland. Growth, establishment and recruitment of selected saltmarsh species were investigated on an area of land excavated from the pasture adjacent to the marsh. The aim of this investigation was to instigate issues such as the design, implementation and assessment of saltmarsh habitat rehabilitation and creation. Together thesis investigations in the two estuaries indicate that restoration and rehabilitation of estuarine habitats is possible and practical, and provide strong environmental values which in turn will provide social and economic benefits. The combined empirical and experimental investigations indicate that with the restoration of tidal flows, water quality will improve and vegetation will reset to a condition resembling the communities prior to the truncation or restriction of the tidal regimes. Whilst it is difficult to predict with accuracy the timeframe and the trajectory of the outcomes it is clear that the desired natural estuarine vegetation will return with careful management. Unlike other terrestrial restorations, any successional stages the restoration goes through will be an interaction of the temporal development of the mangrove and saltmarsh communities rather than one community necessarily preparing the ground for the later community. There is evidence that the intertidal ranges of the two communities overlap somewhat and that mangrove is the competitive dominant. There is no evidence that saltmarsh is a necessary precursor to mangrove in this range. Examination of selected components of the estuarine ecosystems indicate that, with the restoration of tidal flows there will be a positive effect on estuarine benthic invertabrates and estuarine waterbird community diversity and productivity in the rehabilitated habitats. With the restoration of natural estuarine flora and fauna communities there is predicted to be an increase in ecosystem resources such as fish and shellfish nurseries and a reduction in costly episodes related to poor water quality.

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Abrantes, Kátya Gisela dos Santos. "Trophic structure and the importance of terrestrial wetland producers for aquatic food webs in tropical Australian estuaries /." 2008. http://eprints.jcu.edu.au/1989.

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Abrantes, Kátya Gisela dos Santos. "Trophic structure and the importance of terrestrial wetland producers for aquatic food webs in tropical Australian estuaries." Thesis, 2008. https://researchonline.jcu.edu.au/1989/1/01front.pdf.

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Estuaries support a great density and diversity of life and are traditionally considered to be important nursery areas for a variety of species, providing abundant and essential food supply and refuge from predation for juveniles of several fish and invertebrate species. However, to date no study has provided unequivocal evidence supporting this paradigm. In fact, recent studies based on the analysis of stable isotopes have shown that the importance of estuarine terrestrial wetland habitats such as mangroves and salt marsh in supplying energy to animals in adjacent aquatic habitats is not as significant as once thought. The objective of the present thesis is use stable isotopic analysis to clarify the importance of terrestrial wetland productivity as a source of energy for estuarine communities in the Australian Wet and Dry Tropics and to study the processes of energy flow taking place in these systems. Overall, material of terrestrial wetland origin was found to be incorporated into estuarine food webs in Tropical Australia. However, this importance is dependent on several physical and ecological factors including productivity of the different habitats, type and extension of wetland vegetation and connectivity. In a first study, stable isotope analysis of carbon and nitrogen were used to analyse processes of energy flow and assess the extend to which carbon fixed by terrestrial plants is incorporated into adjacent aquatic food webs in two intermittently connected estuarine pools in the Ross River floodplain in North Queensland, Australia. The two pools differed in surrounding vegetation as one was surrounded by mangroves and the other by the salt couch Sporobolus virginicus. Since δ13C values of C3 mangroves (low δ13C) are very different from those of the C4 salt couch (high δ13C), it was possible to determine the importance of terrestrial wetland producers by comparing isotope values of consumers between sites. The IsoSource model was also used to clarify the importance of the different potential sources to consumers. An incorporation mangrove and S. virginicus material was detected for several fish and invertebrate species at both sites, indicating that carbon of terrestrial origin is incorporated in the estuarine food web. A linear negative relationship between δ13C and δ15N was also detected for primary producers, primary consumers and secondary consumers at the Sporobolus pool. This relationship was similar for the different trophic levels and was found to be useful to calculate trophic positions. A food web of ~3.5 trophic levels was found at both pools. In a more detailed study, δ13C and δ15N analysis was used to determine the extent to which carbon of terrestrial origin is important for nutrition of juveniles of four penaeid prawn species, and to detect and describe ontogenetic variations in diet. These species were selected because penaeids are known to depend on estuarine wetland habitats such as mangroves and salt marsh at their juvenile stage. Although an incorporation of mangrove and salt marsh carbon was detected, it was not of a major importance for any species, and autochthonous sources seemed more important. Ontogenetic shifts in diet were detected for Penaeus (Fenneropenaeus) merguiensis, Metapenaeus bennetae and Penaeus esculentus, and corresponded to an increase in mean trophic level as well as to changes in the ultimate sources of energy. In a broader scale study, the incorporation of terrestrial wetland productivity in estuarine food webs was studied in four open estuarine systems in Tropical Australia. These included a near-pristine system in the Wet Tropics (Deluge Inlet), two impacted systems in the Wet Tropics (Victoria and Half Moon Creeks), and a near pristine system in the Dry Tropics (Blacksoil Creek). Incorporation of mangrove derived carbon was detected for Deluge Inlet and Victoria Creek and incorporation of carbon of sugarcane origin was also detected for fish from Victoria Creek. The degree of incorporation of mangrove carbon into estuarine food webs seemed to relate directly to the type and extent of mangrove vegetation adjacent to the estuary. Trophic structure differed between estuaries, but in all areas a constant trophic length with about four trophic levels was detected. Stable isotope results also suggest a high level of omnivory and diet overlap between fish species at Deluge Inlet, Half Moon Creek and Blacksoil Creek, but not for the agriculture impacted system of Victoria Creek, which can be a reflection of the great level of anthropogenic impact in this area. In a final study, the seasonality in importance of autochthonous and allochthonous carbon for aquatic communities in six intermittently connected estuarine areas of the Australian Dry Tropics was investigated. Results varied between sites, depending of site-specific ecological conditions. The hydrology regime was a major factor controlling the sources of energy in these areas, controlling the amount of terrestrial material available to aquatic animals throughout the year and allowing the presence of an energetic connectivity between the terrestrial and aquatic environments. An important seasonal variation in the main sources of energy was detected in two systems, where a greater incorporation of carbon of terrestrial origin was present after the wet season. Hence, aquatic food webs may rely alternatively on autochthonous and allochthonous sources of energy, depending on the season. Trophic organization, including level of omnivory, diet overlap and trophic length, was also found to differ between systems and seasons due to differences in species composition, resource availability, connectivity, and type and level of environmental disturbances. While trophic length seems to be similar between open estuarine areas, with food webs having ~4 trophic levels, in intermittently connected areas trophic length was more variable between systems, with between 3.2 and 4 trophic levels.

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