Journal articles on the topic 'Estuaries Australia'
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1
Gillanders, Bronwyn M., Travis S. Elsdon, Ian A. Halliday, Gregory P. Jenkins, Julie B. Robins, and Fiona J. Valesini. "Potential effects of climate change on Australian estuaries and fish utilising estuaries: a review." Marine and Freshwater Research 62, no. 9 (2011): 1115. http://dx.doi.org/10.1071/mf11047.
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Estuaries are especially vulnerable to the impacts of climate change because changes in climatic and hydrologic variables that influence freshwater and marine systems will also affect estuaries. We review potential impacts of climate change on Australian estuaries and their fish. Geographic differences are likely because southern Australian climates are predicted to become warmer and drier, whereas northern regions may see increased precipitation. Environmental factors, including salinity gradients, suspended sediment, dissolved oxygen and nutrient concentrations, will be influenced by changing freshwater input and other climate variables. Potential impacts will vary depending on the geomorphology of the estuary and the level of build-up of sand bars across estuarine entrances. Changes to estuarine fish assemblages will depend on associated changes to salinity and estuarine-mouth morphology. Marine migrants may be severely affected by closure of estuarine mouths, depending on whether species ‘must’ use estuarine habitat and the level of migratory v. resident individuals. Depending on how fish in coastal waters locate estuaries, there may be reduced cues associated with estuarine mouths, particularly in southern Australia, potentially influencing abundance. In summary, climate change is expected to have major consequences for Australian estuaries and associated fish, although the nature of impacts will show significant regional variation.
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Tremblin, Clément M., Maria Holzmann, Justin H. Parker, Aleksey Sadekov, and David W. Haig. "Invasive Japanese foraminifera in a south-west Australian estuary." Marine and Freshwater Research 73, no. 3 (November 24, 2021): 328–42. http://dx.doi.org/10.1071/mf21254.
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An invasive foraminiferan is recorded for the first time in an Australian estuary. Trochammina hadai, originally described as endemic from Japan and subsequently found to be alien in coastal waters of California and Brazil, has been identified in estuarine sediment in the vicinity of Bunbury Port in Western Australia. Species determination is based on morphological, molecular and ecological similarities to the Japanese type. The species has not been recorded in other estuaries in Australia. Bunbury Port is a major exporter of woodchip to Japan and the introduction of T. hadai may have come from ballast water out of shallow-draught woodchip vessels. Small sediment samples of estuarine mud obtained at water depths of ~5 m contain abundant T. hadai (on average ~0.4 mm in adult diameter) that are easily recognised in microscopic view of the sediment surface by their bright reddish-brown colour. The collection of sediment samples from the estuarine floor and ballast water, and the examination of these for foraminifers, may provide a useful indicator in estuaries for the possible presence of other exotic species, particularly in the vicinity of ports.
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Hodgkin, Ernest P., and Patrick Hesp. "Estuaries to salt lakes: Holocene transformation of the estuarine ecosystems of south-western Australia." Marine and Freshwater Research 49, no. 3 (1998): 183. http://dx.doi.org/10.1071/mf96109.
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When the estuaries of south-western Australia were first flooded by the Holocene marine transgression about 7000 years before present (BP), most were enclosed by limestone barrier dunes. Coastal sand drift built bars and flood-tide deltas in the narrow entrances, but until about 3500 years BP the estuaries remained tidal-dominated systems with a diverse marine–estuarine fauna. Now the bars/deltas so obstruct the small tides that estuary water is fresh in winter and marine to hypersaline in summer; the estuaries are river-flow-dominated systems and the ecosystems are characterised by a restricted euryhaline estuarine biota. Some estuaries are still permanently open, their bars/deltas never close, and some are seasonally open, their bars open with river flow in winter and close in summer. Other estuaries are normally closed, their bars remain closed for several years and break with episodic flood flow, or are permanently closed coastal salt lakes with bars that never or rarely break: they can become grossly hypersaline and may dry up altogether. An hypothesis to explain this Holocene transformation of the estuaries attributes it principally to sedimentary processes in an environment where river flow is highly seasonal, tides are microtidal, there was a fall in sea level, and there are differences in the volume and periodicity of flow and the degree of shelter to the entrances from the prevailing south-west winds and swell.
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O'Mara, K., A. Miskiewicz, and M. Y. L. Wong. "Estuarine characteristics, water quality and heavy metal contamination as determinants of fish species composition in intermittently open estuaries." Marine and Freshwater Research 68, no. 5 (2017): 941. http://dx.doi.org/10.1071/mf15409.
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Estuaries are critical aquatic environments that are used by many fish during their life cycle. However, estuaries often suffer from poor water quality as a result of anthropogenic activities. Fish diversity studies in estuaries are common, although few have examined whether correlations exist between water quality, metal contamination and fish assemblages. In the present study we investigated the effect of abiotic conditions, heavy metals and estuary characteristics on the abundance, diversity and composition of fish in four intermittently open estuaries along the Illawarra coast of south-eastern Australia. The heterogeneity of environmental conditions was reflected in the fish assemblages in each estuary. Environmental variables predicted fish species composition, and estuaries in particularly poor condition contained few species (estuarine residents) in high abundance, indicating their ability to acclimatise and survive in conditions that are hostile to other species. Overall, these findings demonstrate that estuarine fish assemblages may be useful indicators of estuary condition and reveal the importance of managing anthropogenic activities in the surrounding catchment to improve water quality so that biodiversity of fish can be restored in these estuarine environments.
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Fury, Christine A., and Peter L. Harrison. "Abundance, site fidelity and range patterns of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in two Australian subtropical estuaries." Marine and Freshwater Research 59, no. 11 (2008): 1015. http://dx.doi.org/10.1071/mf08109.
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Bottlenose dolphins are widely studied in marine habitats, but information on estuarine populations is very limited. The present study provides the first published data on bottlenose dolphins in Australian estuaries. Abundance estimates, site fidelity and individual ranging patterns were examined over a 3-year period for Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting the Clarence River (CR) and Richmond River (RR) estuaries in northern New South Wales, Australia. Mark–recapture analyses estimated 71 (62–81 95% CI) dolphins utilised the CR whereas 34 (19–49 95% CI) used the RR. Differences in site fidelity were observed between the estuaries, with 60% and 37% of identified dolphins determined as residents, 26% and 21% as occasional visitors and 14% and 42% as transients for the CR and RR respectively. Resource partitioning was apparent in both estuaries with the mean distance resident dolphins were found upstream from the river mouth being greater than occasional visitors and transients. The Clarence River sustains a larger, predominantly resident dolphin community compared with the Richmond River, which supports a relatively small dolphin community with lower site fidelity. Management of future increased anthropogenic disturbances is needed to ensure the long-term survival of these dolphin populations.
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Hadwen, Wade L., Grant L. Russell, and Angela H. Arthington. "Gut content- and stable isotope-derived diets of four commercially and recreationally important fish species in two intermittently open estuaries." Marine and Freshwater Research 58, no. 4 (2007): 363. http://dx.doi.org/10.1071/mf06157.
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Despite remaining closed for variable periods, intermittently open estuaries provide habitat for estuarine and marine fish species of commercial and recreational value. To better understand how these systems trophically support their fish assemblages, the diets of four valued fish species, namely Acanthopagrus australis, Platycephalus fuscus, Sillago ciliata and Mugil cephalus, were examined in two intermittently open estuaries in New South Wales, Australia. Fish diets were determined using both gut contents and stable isotope analyses because the different temporal resolutions afforded by these methods can provide insight into the flexibility of fish diets. Stable isotope signatures of prey and fish proved to be particularly useful in analyses of the diets of M. cephalus and P. fuscus, because these species consume large quantities of unidentifiable organic matter and have high incidences of empty guts respectively. Diet reconstructions across methods were generally consistent for A. australis, but differed substantially for S. ciliata, with fewer prey taxa identified in the guts than expected. This result suggests that individual S. ciliata switch between local resources on the basis of their fluctuating temporal availability. Trophic flexibility, coupled with broad physicochemical tolerances, enables these species to flourish in the challenging environment of intermittently open estuaries.
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Pusey, Bradley J., Mark J. Kennard, Helen K. Larson, Quentin Alsop, Michael Hammer, and Duncan J. Buckle. "Estuarine fishes of the South Alligator River, Kakadu National Park, northern Australia." Marine and Freshwater Research 67, no. 12 (2016): 1797. http://dx.doi.org/10.1071/mf15221.
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Estuaries are recognised globally as areas of high production, diversity and high economic value. Exploitation of the economic potential of estuaries and attendant infrastructural development plus expansion of human populations has resulted in degradation of estuaries worldwide. Many estuaries of northern Australia, in contrast, remain in good ecological condition. The estuarine fish fauna of the South Alligator River, Kakadu region of northern Australia was investigated to determine seasonal and spatial variation in composition. Beam trawls were used at 94 locations over the wet and dry seasons of 2012. In total, 81 taxa were collected, 26 of which had not previously been recorded in the river. Sciaenidae and Engraulidae dominated species richness and abundance. Samples were heterogeneous in terms of composition and abundance in a manner unrelated to any measured aspect of the habitat over which trawls occurred. Species richness was higher in the lower estuary than the upper estuary and more species were detected during the wet season. Turnover in assemblage structure between sampling occasions was associated with seasonal variation in discharge concordant with changes in salinity and potentially productivity. Compositional variation was largely ascribed to differential spawning phenology of adults and tolerance to fluctuating salinity. The Kakadu region supports a rich fish fauna moderately distinct from that observed elsewhere in the Northern Territory. Pronounced temporal turnover in assemblage structure and spatial variation at a variety of scales (i.e. within samples, and within and between rivers) collectively pose a challenge to management in light of ongoing and proposed development of the water resources of northern Australia, including its estuaries.
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Creighton, Colin, Paul I. Boon, Justin D. Brookes, and Marcus Sheaves. "Repairing Australia's estuaries for improved fisheries production – what benefits, at what cost?" Marine and Freshwater Research 66, no. 6 (2015): 493. http://dx.doi.org/10.1071/mf14041.
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An Australia-wide assessment of ~1000 estuaries and embayments undertaken by the National Land and Water Resources Audit of 1997–2002 indicated that ~30% were modified to some degree. The most highly degraded were in New South Wales, where ~40% were classified as ‘extensively modified’ and <10% were ‘near pristine’. Since that review, urban populations have continued to grow rapidly, and increasing pressures for industrial and agricultural development in the coastal zone have resulted in ongoing degradation of Australia's estuaries and embayments. This degradation has had serious effects on biodiversity, and commercial and recreational fishing. A business case is developed that shows that an Australia-wide investment of AU$350 million into repair will be returned in less than 5 years. This return is merely from improved productivity of commercial fisheries of a limited number of fish, shellfish and crustacean species. Estuary repair represents an outstanding return on investment, possibly far greater than most of Australia's previous environmental repair initiatives and with clearly demonstrated outcomes across the Australian food and services economies.
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Ferrell, DJ, SE McNeill, DG Worthington, and JD Bell. "Temporal and spatial variation in the abundance of fish associated with the seagrass Posidonia australis in South-eastern Australia." Marine and Freshwater Research 44, no. 6 (1993): 881. http://dx.doi.org/10.1071/mf9930881.
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A beam trawl was used to sample fish associated with the seagrass Posidonia australis between September 1988 and June 1990. We describe variation in abundance of fish at two spatial scales: among three seagrass beds 1-10 km apart within each of three estuaries, and among the estuaries separated by at least 100 km. Most species had significant differences in abundance among sites and estuaries that changed through time. However, many species also had consistent patterns in abundance among sites and among estuaries. For example, there were large and consistent differences in the abundance of many species among the three estuaries. Widespread changes in abundance (ie: changes that took place at all sites within an estuary or in most estuaries) were not common. The two spatial scales used in this study are also logical scales for management of seagrass habitats. The consistent differences in abundance of some fish found at both spatial scales will complicate management decisions.
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Watts, Robyn J., and Michael S. Johnson. "Estuaries, lagoons and enclosed embayments: habitats that enhance population subdivision of inshore fishes." Marine and Freshwater Research 55, no. 7 (2004): 641. http://dx.doi.org/10.1071/mf04051.
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Several studies have suggested that estuaries, lagoons and enclosed embayments may offer special opportunities for local subdivision in marine species. We used data from published papers and unpublished theses to examine the effect of such water bodies on allozyme differentiation of seven species of inshore fishes in Western Australia. We included species that differ in their dispersal, and hence their intrinsic potential for gene flow. Over large distances, subdivision was generally greater among estuarine populations than among conspecific marine populations collected over similar distances. Over small distances, paired marine and estuarine samples were generally more divergent than pairs of marine samples separated by similar distances. For species with a low capability for dispersal, estuaries appear to add to the high levels of genetic subdivision that commonly result from other factors. Under special circumstances estuaries may also provide opportunities for genetic divergence in species with a high capability of dispersal that are rarely subdivided at a large geographical scale. These observations indicate that estuaries can increase the genetic subdivision of populations of inshore fishes, and that species that use both marine and estuarine habitats are likely to have greater genetic subdivision than those that are restricted to marine habitats.
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Logan, Brendan, Kathryn H. Taffs, and Laura Cunningham. "Applying paleolimnological techniques in estuaries: a cautionary case study from Moreton Bay, Australia." Marine and Freshwater Research 61, no. 9 (2010): 1039. http://dx.doi.org/10.1071/mf09277.
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Paleoecological techniques are useful tools to identify restoration targets and natural variability for natural resource management programs. However, despite recent advances, caution is required when employing paleoecological techniques in estuaries, due to their dynamic nature relative to lake environments where these techniques were pioneered. This study used a novel combination of chronological, diatom, geochemical and isotopic data to assess the effectiveness of using these techniques in estuaries, and to develop an understanding of environmental changes within Moreton Bay, an open estuarine environment in subtropical east Australia. Results indicated mixed success, with 210Pb results indicating only background unsupported 210Pb levels, 14C results indicating sediment deposition from mixed sources, no diatom preservation and inconsistencies between geochemical and isotope proxies. Evidence did exist that the Moreton Bay sediments have been derived from different sources over the past 10 000 years. However, isotope records were not able to identify the likely sources of these sediments. Problems with diatom preservation were most probably due to the high salinity and temperatures associated with subtropical open embayment estuaries. Future studies attempting to identify environmental histories of estuaries should incorporate river-influenced locations rather than marine-dominated sites to ensure better diatom preservation and more definitive geochemical signals.
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Henderson, Christopher J., Ben L. Gilby, Thomas A. Schlacher, Rod M. Connolly, Marcus Sheaves, Nicole Flint, Hayden P. Borland, and Andrew D. Olds. "Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes." ICES Journal of Marine Science 76, no. 4 (February 4, 2019): 1052–61. http://dx.doi.org/10.1093/icesjms/fsz007.
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Abstract Coastal seascapes are composed of a diversity of habitats that are linked in space and time by the movement of organisms. The context and configuration of coastal ecosystems shapes many important properties of animal assemblages, but potential seascape effects of natural and artificial habitats on nearby habitats are typically considered in isolation. We test whether, and how, the seascape context of natural and urban habitats modified fish assemblages across estuaries. Fish were sampled with underwater videos in five habitat types (mangroves, rock bars, log snags, unvegetated sediments, armoured shorelines) in 17 estuaries in eastern Australia. Different habitats supported distinct fish assemblages, but the spatial context of mangroves and armoured shorelines had pervasive ecological effects that extended across entire estuaries. In most estuarine habitats, fish diversity and abundance was greatest when they were in close proximity of mangroves, and decreased due to the proximity of armoured shorelines. Many cities are centred on estuaries, and urban expansion is often associated with the fragmentation of mangrove forests. Our findings emphasize that these transformations of urban estuarine landscapes are likely to propagate to broader ecological impacts detectable in multiple habitats beyond mangrove forests.
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McSweeney, SL, DM Kennedy, and ID Rutherfurd. "A geomorphic classification of intermittently open/closed estuaries (IOCE) derived from estuaries in Victoria, Australia." Progress in Physical Geography: Earth and Environment 41, no. 4 (May 26, 2017): 421–49. http://dx.doi.org/10.1177/0309133317709745.
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A large proportion of estuaries along microtidal wave-dominated coastlines worldwide have entrances that intermittently close to the ocean when tidal currents and fluvial discharge are insufficient to erode sediment delivered onshore by waves. In this study, these systems are termed “intermittently open/closed estuaries” (IOCE) in order to include all estuaries which intermittently close to the ocean. IOCE do not fit neatly into existing generalized estuary classification models and have been traditionally recognized as a single estuary type that constitute a rare subset of wave-dominated estuaries. In this study, 111 estuaries in Victoria, Australia, are used to develop a classification model that delineates between different IOCE types. This was undertaken using historic aerial imagery and quantification of the estuary channel width, catchment area, lagoon dimensions and tidal prism derived from remotely sensed data. Field surveying of entrance morphology was undertaken for a subsample of 35 IOCE characteristic of each section of the coast and which had detailed entrance condition records. Using this subset, IOCE were classified into three distinct types using multiple methods of statistical delineation (non-metric multidimensional scaling, hierarchical cluster analysis and distribution analysis). These three types are: (1) Type A, the largest IOCE which both close and open infrequently but for the longest durations; (2) Type B, medium sized IOCE which open and close several times per year for weekly to monthly durations; and (3) Type C (tidal creeks), the smallest IOCE located specifically in high rainfall, mountainous catchments and which exist in a predominantly open state. The three types of IOCE showed an order of magnitude difference in entrance closure duration as controlled by variations in the catchment area, tidal prism volume, dimensions of the estuarine lagoon and the entrance channel at the mouth. The classification is also applicable to wave-dominated coastlines internationally where IOCE are present.
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Whitfield, A. "Predation on small juvenile fishes in shallow estuarine nursery areas: Reply to Baker & Sheaves (2021)." Marine Ecology Progress Series 662 (March 18, 2021): 209–14. http://dx.doi.org/10.3354/meps13678.
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The key criticism by Baker & Sheaves (2021; Mar Ecol Prog Ser 662:205-208) of the Whitfield (2020; Mar Ecol Prog Ser 649:219-234) estuarine littoral predation paradigm review is that shallow water fish nursery habitats contain abundant predator assemblages which may create high predation pressure on the juvenile fish cohorts that occupy these areas. The primary arguments supporting Baker & Sheaves’ criticism arise from a series of papers published by them on piscivorous fish predation in certain tropical Australian estuaries. The counter-argument that shallow littoral areas in estuaries do indeed provide small juvenile fishes with refuge from small and large piscivorous fishes is provided by published papers from 4 different estuary types in South Africa, covering both subtropical and warm-temperate systems. Based on the overall published information, the argument for shallow (<1 m depth) estuarine waters providing major protection for newly settled juveniles appears to be weak in northern Australia but strong in South Africa. The global situation, as outlined in this response, is more supportive of low piscivorous predation in shallow nursery habitats, but further targeted research is needed before we can confirm that littoral estuarine waters are indeed a universal keystone attribute in this regard.
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Acha, Eduardo M., Hermes Mianzan, Carlos A. Lasta, and Raúl A. Guerrero. "Estuarine spawning of the whitemouth croaker Micropogonias furnieri (Pisces : Sciaenidae), in the Río de la Plata, Argentina." Marine and Freshwater Research 50, no. 1 (1999): 57. http://dx.doi.org/10.1071/mf98045.
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Most fishes that take advantage of the high productivity of estuaries exhibit offshore spawning, produce great numbers of small pelagic eggs and recruit to estuaries as larvae or juveniles. The reproductive pattern of Micropogonias furnieri (a planktonic egg spawner) in the Río de la Plata estuary (36°S,56°W) differs from this. Biological sampling and oceanographic data showed that the spawning area covers a narrow band across the river between Montevideo (34°50´8S,56°10´W) and Punta Piedras (35°25´S,57°10´W) at depths ranging from 6 to 8 m. This area is characterized by strong haloclines, reaching 21.5 units m-1. M. furnieri eggs were present only below the halocline, in salinities of 9.7–27.3, and at 18.5–20.2°C. Spawning occurred in the innermost part of the estuary, near the upstream edge of the salinity wedge and coinciding with the turbidity maximum (up to 150 mg L-1). The regular spawning of pelagic eggs has been reported in estuaries of southern Africa and Australia characterized by intermittent landlocking. The present results show that a large estuary may also provide the opportunity for successful spawning of pelagic eggs. Resumen. La mayoría de los peces que aprovechan la alta productividad de los estuarios efectúan sus desoves en el océano, producen gran cantidad de pequeños huevos pelágicos, y se reclutan a los estuarios como larvas o juveniles. El patrón reproductivo de Micropogonias furnieri (un desovante de huevos planctónicos) en el Río de la Plata (36°S,56°W), resulta diferente. Muestreos biológicos y datos oceanográficos demuestran que su área de desove cubre una estrecha franja a través del río, entre Montevideo (34°50´S,56°10´W) y Punta Piedras (35°25´S,57°10´W), en profundidades de 6 a 8 m. Esta área se caracteriza por fuertes haloclinas, de hasta 21.5 unidades m-1. Los huevos de M. furnieri se encuentran sólo debajo de la haloclina, en salinidades de 9.7 a 27.3, y temperaturas de 18.5° a 20.2°C. El desove tiene lugar en la parte más interna del estuario, cerca del límite río arriba de la cuña salina, y en coincidencia con el máximo de turbidez (hasta 150 mg L-1). En estuarios del sur de Africa y Australia, caracterizados por el cierre intermitente de su boca, ha sido reportado el desove regular de huevos planctónicos. Nuestros resultados demuestran que un gran estuario también puede proveer la oportunidad para el desove exitoso de huevos planctónicos.
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Henderson, Christopher J., Ben L. Gilby, Edward Stone, Hayden P. Borland, and Andrew D. Olds. "Seascape heterogeneity modifies estuarine fish assemblages in mangrove forests." ICES Journal of Marine Science 78, no. 3 (February 12, 2021): 1108–16. http://dx.doi.org/10.1093/icesjms/fsab022.
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Abstract Mangroves are a dominant structural habitat within tropical and subtropical estuaries that provide a number of ecosystem services, including habitat for a range of crustaceans and fish. However, mangroves are one of the most threatened estuarine habitats globally, having been severely reduced in extent, and replaced by urban structures. Here, we test for the effects of both natural (e.g. seagrass, rock and mangroves habitat extent, and connectivity) and human (e.g. extent of urban area) landscape variables on the number and type of fish inhabiting mangroves forests. We used remote underwater video stations to quantify fish assemblages within mangroves at 150 sites in 30 estuaries across Queensland, Australia. Fish community structure was best explained by the extent of mangroves and seagrasses within an estuary, the distance to the estuary mouth, and the size of the estuary and catchment. Moderate catchment size and proximity to the estuary mouth increased species richness and abundance of harvestable fish at individual mangrove sites. In order to maintain mangrove fish assemblages and the functions they provide, management initiatives should focus on maintaining natural estuarine seascapes that are located closer to the mouth of estuaries, in particular, focusing on estuaries that have lower levels of catchment urbanization.
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Potter, I. C., and G. A. Hyndes. "Characteristics of the ichthyofaunas of southwestern Australian estuaries, including comparisons with holarctic estuaries and estuaries elsewhere in temperate Australia: A review." Austral Ecology 24, no. 4 (August 1999): 395–421. http://dx.doi.org/10.1046/j.1442-9993.1999.00980.x.
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Ferretto, Giulia, Adriana Vergés, Alistair G. B. Poore, Tim M. Glasby, and Kingsley J. Griffin. "Habitat Provision and Erosion Are Influenced by Seagrass Meadow Complexity: A Seascape Perspective." Diversity 15, no. 2 (January 17, 2023): 125. http://dx.doi.org/10.3390/d15020125.
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Habitat complexity plays a critical role in shaping biotic assemblages and ecosystem processes. While the impacts of large differences in habitat complexity are often well understood, we know less about how subtle differences in structure affect key ecosystem functions or properties such as biodiversity and biomass. The late-successional seagrass Posidonia australis creates vital habitat for diverse fauna in temperate Australia. Long-term human impacts have led to the decline of P. australis in some estuaries of eastern Australia, where it is now classified as an endangered ecological community. We examined the influence of P. australis structural complexity at small (seagrass density) and large (meadow fragmentation) spatial scales on fish and epifauna communities, predation and sediment erosion. Fine-scale spatially balanced sampling was evenly distributed across a suite of environmental covariates within six estuaries in eastern Australia using the Generalised Random Tessellation Structures approach. We found reduced erosion in areas with higher P. australis density, greater abundance of fish in more fragmented areas and higher fish richness in vegetated areas further from patch edges. The abundance of epifauna and fish, and fish species richness were higher in areas with lower seagrass density (seagrass density did not correlate with distance to patch edge). These findings can inform seagrass restoration efforts by identifying meadow characteristics that influence ecological functions and processes.
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Hicks, Andy, Nicole C. Barbee, Stephen E. Swearer, and Barbara J. Downes. "Estuarine geomorphology and low salinity requirement for fertilisation influence spawning site location in the diadromous fish, Galaxias maculatus." Marine and Freshwater Research 61, no. 11 (2010): 1252. http://dx.doi.org/10.1071/mf10011.
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In habitats such as estuaries, which are characterised by large and fluctuating gradients in abiotic variables, finding appropriate habitat for successful spawning and egg development can be critical to a species’ survival. We explored how salinity requirements for successful fertilisation may govern the distribution of estuarine spawning habitat for the diadromous fish, Galaxias maculatus, which spawns in inundated vegetation on estuary banks during spring tides. Artificial fertilisation experiments confirmed that successful fertilisation only occurs at low salinities (<20). Thus, we predicted that egg distributions would depend upon the extent of low-salinity surface waters in an estuary. Using estuary geomorphology classification schemes, which classify estuaries by physical and chemical characteristics such as their salinity dynamics, we hypothesised that stratified estuaries would provide a greater extent of low salinity surface water than well-mixed estuaries. This prediction was supported by surveys of egg distributions in five estuaries in Victoria, Australia. Eggs were distributed over a greater proportion of ‘stratified’ v. ‘mixed’ estuary types. We suggest that combining knowledge of the spawning requirements of a species and physical properties of the habitat, such as those encapsulated in estuary geomorphic classification schemes, can greatly facilitate efforts to identify critical habitats and thus aid in species management and conservation.
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Hurwood, David A., Mike P. Heasman, and Peter B. Mather. "Gene flow, colonisation and demographic history of the flat oyster Ostrea angasi." Marine and Freshwater Research 56, no. 8 (2005): 1099. http://dx.doi.org/10.1071/mf04261.
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The Australian flat oyster Ostrea angasi is currently being assessed for its potential as a species for culture in New South Wales. It is considered important to determine the population genetic structure of wild stocks among estuaries before translocation of juveniles (spat) for growout in order to avoid possible deleterious effects of hybridisation of genetically divergent stocks (i.e. outbreeding depression). Five estuaries were sampled in southern New South Wales as well as another four from across the natural range of the species in Australia. Sequence analysis of a 594 base pair fragment of the mitochondrial cytochrome oxidase I gene was used to determine the degree of population structuring inferred from pairwise ΦST estimates and spatial analysis of molecular variance analysis. The analyses revealed that there is no significant genetic differentiation among the sampled New South Wales estuaries (P > 0.05) and all eastern samples represent a geographically homogeneous population. This essentially removes any potential constraints on broodstock sourcing and spat translocation within this region. Although levels of differentiation among all sites varied, little divergence was evident across the entire range of the sample. Furthermore, the study revealed extremely low levels of divergence between O. angasi and its northern hemisphere congener, O. edulis, raising the possibility that O. angasi may have only recently colonised Australian estuaries.
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Walsh, CJ, and BD Mitchell. "The Freshwater shrimp Paratya australiensis (Kemp, 1917) (Decapoda:Atyidae) in estuaries of south-westren victoria, Australia." Marine and Freshwater Research 46, no. 6 (1995): 959. http://dx.doi.org/10.1071/mf9950959.
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All life-cycle stages of Paratya australiensis, formerly thought to occur predominantly in freshwater environments, were found to be common in estuaries of western Victoria. Highest densities of larvae were found below the halocline in stable, open, well developed, salt-wedge estuaries. Larvae developed in the salt wedge, and juveniles recruited to littoral weed beds. Adults were most abundant in low salinities among submerged, leafy macrophytes. Although recruitment to estuaries permits the avoidance of fatal drift of larvae to sea, tolerance of saline conditions may permit rare dispersal of larvae between estuaries. A new model for the biogeography of Paratya is proposed.
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Gray, CA, DJ McElligott, and RC Chick. "Intra- and inter-estuary differences in assemblages of fishes associated with shallow seagrass and bare sand." Marine and Freshwater Research 47, no. 5 (1996): 723. http://dx.doi.org/10.1071/mf9960723.
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Differences in the assemblages of fishes associated with the seagrass Zostera capricorni and bare sand were assessed across eight estuaries spanning 300 km of the coast of northern New South Wales, Australia. Assemblages consistently differed between habitats in all estuaries, as species affinities within each habitat were relatively consistent. A greater diversity and abundance of fishes generally occurred over seagrass than over sand. Great variation in the abundances of individual species was evident but there were no consistent geographic (inter-estuary) effects. The abundances of most species varied as much between locations (0.5-2.0 km apart) within each estuary as among estuaries (15-300 km apart). Juveniles of economically important species occurred over seagrass (e.g. Rhabdosargus sarba, Acanthopagrus australis, Girella tricuspidata) and sand (e.g. Sillago ciliata). Before the true value of different nursery habitats to fisheries resources can be identified, the contribution of the juvenile fishes residing in the different nursery habitats to future (exploited) populations needs to be quantified.
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Dortch, Charles. "Prehistory Down Under: archaeological investigations of submerged Aboriginal sites at Lake Jasper, Western Australia." Antiquity 71, no. 271 (March 1997): 116–23. http://dx.doi.org/10.1017/s0003598x0008460x.
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Much of Australian prehistory lies under water. Although confined to the continent's extreme southwestern corner, field studies described in this report show that this submerged prehistoric component is very real, with numerous archaeological sites and former land surfaces awaiting investigation on the floors of Australia's lakes, rivers and estuaries, and on its submerged continental margins.
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Mills, Courtenay E., Wade L. Hadwen, and Jane M. Hughes. "Looking through glassfish: marine genetic structure in an estuarine species." Marine and Freshwater Research 59, no. 7 (2008): 627. http://dx.doi.org/10.1071/mf07215.
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Through the use of mitochondrial DNA (ATP8 gene), the prediction of intermediate genetic structuring was investigated in two species of estuarine glassfish (Ambassis marianus and Ambassis jacksoniensis) (Perciformes : Ambassidae) to determine the possibility of a generalised ‘estuarine’ genetic structure. Individuals were collected from estuaries in eastern Australia between Tin Can Bay (Queensland) in the north and Kempsey (New South Wales) in the south. Analysis of the haplotype frequencies found in this region suggested panmictic populations with star-like phylogenies with extremely high levels of genetic diversity, but with no correlation between geographic distance and genetic distance. Non-significant FST and ΦST suggested extensive dispersal among estuaries. However, Tajima’s D and Fu’s FS values suggest ‘mutation–genetic drift equilibrium’ has not been reached, and that population expansions occurring 262 000 (A. marianus) and 300 000 (A. jacksoniensis) years ago may obscure any phylogeographic structuring or isolation by distance. The finding of panmixia was contrary to the prediction of genetic structuring intermediate between that of marine fish (shallowly structured) and freshwater fish (highly structured), suggesting high dispersal capabilities in these species.
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Halliday, Ian A., Julie B. Robins, David G. Mayer, Jonathan Staunton-Smith, and Michelle J. Sellin. "Effects of freshwater flow on the year-class strength of a non-diadromous estuarine finfish, king threadfin (Polydactylus macrochir), in a dry-tropical estuary." Marine and Freshwater Research 59, no. 2 (2008): 157. http://dx.doi.org/10.1071/mf07077.
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The year-class strength of the commercial catch of king threadfin (Polydactylus macrochir (Gunther, 1876)) was correlated with freshwater flows into a dry-tropical estuary over five consecutive years. The year-class strength of king threadfin, a non-diadromous estuarine species, fluctuated and correlated significantly with freshwater flow and coastal rainfall in spring and summer; a result similar to that found for the catadromous barramundi (Lates calcarifer) within the same estuarine system. All sub-sets general linear models were used to screen relationships between year-class strength and freshwater variables. King threadfin spawn from spring to summer in north-eastern Australia, when hydrological conditions adjacent to estuaries have high salinities and are optimal for egg and post-larval survival. Young-of-the-year enter estuaries during the wet season, enabling them to take advantage of salinity gradients and the seasonal blooms in prey species such as Acetes spp. and juvenile penaeids that are accentuated in wet years. Freshwater flows in spring and summer are important drivers of the year-class strength of estuarine finfish, and reduction in these flows, through the development of water infrastructure and abstraction or long-term climate change, will potentially reduce the size of the population of estuarine fish available for human harvest.
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Cook, Perran L. M., Fiona Y. Warry, Paul Reich, Ralph Mac Nally, and Ryan J. Woodland. "Catchment land use predicts benthic vegetation in small estuaries." PeerJ 6 (February 14, 2018): e4378. http://dx.doi.org/10.7717/peerj.4378.
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Many estuaries are becoming increasingly eutrophic from human activities within their catchments. Nutrient loads often are used to assess risk of eutrophication to estuaries, but such data are expensive and time consuming to obtain. We compared the percent of fertilized land within a catchment, dissolved inorganic nitrogen loads, catchment to estuary area ratio and flushing time as predictors of the proportion of macroalgae to total vegetation within 14 estuaries in south-eastern Australia. The percent of fertilized land within the catchment was the best predictor of the proportion of macroalgae within the estuaries studied. There was a transition to a dominance of macroalgae once the proportion of fertilized land in the catchment exceeded 24%, highlighting the sensitivity of estuaries to catchment land use.
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Saintilan, Neil, and Kerrylee Rogers. "The significance and vulnerability of Australian saltmarshes: implications for management in a changing climate." Marine and Freshwater Research 64, no. 1 (2013): 66. http://dx.doi.org/10.1071/mf12212.
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We review the distribution, status and ecology of Australian saltmarshes and the mechanisms whereby enhanced atmospheric carbon dioxide and associated climate change have influenced and will influence the provision of ecosystem goods and services. Research in temperate and subtropical saltmarsh has demonstrated important trophic contributions to estuarine fisheries, mediated by the synchronised mass-spawning of crabs, which feed predominantly on the C4 saltmarsh grass Sporobolus virginicus and microphytobenthos. Saltmarshes also provide unique feeding and habitat opportunities for several species of threatened microbats and birds, including migratory shorebirds. Saltmarshes increased in extent relative to mangrove in Australia in both tide- and wave-dominated geomorphic settings through the latter Holocene, although historic trends have seen a reversal of this trend. Australian saltmarshes have some capacity to maintain elevation with respect to rising sea level, although in south-eastern Australia, the encroachment of mangrove and, in Tasmania, conversion of shrubland to herbfield in the past half-century are consistent with changes in relative sea level. Modelling of the impacts of projected sea-level rise, incorporating sedimentation and other surface-elevation drivers, suggests that the survival of saltmarsh in developed estuaries will depend on the flexible management of hard structures and other impediments to wetland retreat.
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Kuo, John, and Hugh Kirkman. "Halophila decipiens Ostenfeld in estuaries of southwestern Australia." Aquatic Botany 51, no. 3-4 (August 1995): 335–40. http://dx.doi.org/10.1016/0304-3770(95)00468-f.
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Kingsford, R. T. "Conservation of waterbirds in Australia." Pacific Conservation Biology 19, no. 4 (2013): 366. http://dx.doi.org/10.1071/pc130366.
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There are 93 species of Australian waterbirds, predominantly dependent on freshwater, inland saline or estuarine ecosystems. They include diverse species predominantly from six major groups: grebes (Podicipediformes); ducks, geese and swans (Anseriformes); pelicans and cormorants (Pelecaniformes); egrets, ibises, spoonbills (Ciconniiformes); cranes, rails and crakes (Gruiiformes) and shorebirds (Charadriiformes). I analysed the content of 382 publications on Australian waterbirds in relation to life history and threats. There were 4.08 publications per species, with most publications biased towards the Anseriformes (6.95 publications per species). There were relatively few publications on Gruiformes (1.13 per species) or Podicipediformes (0.33 per species). There is reasonably good knowledge of distribution, abundance, diet and foraging and habitat use, but there were generally few examples of integration of these data into population modelling, a particularly useful tool for conservation of species. Significant gaps exist in the understanding of basic life history and movement patterns, critical for conservation; these are particularly accentuated for cryptic species. Opportunities exist to collection basic information, directed towards modelling population dynamics. As with most of the world’s organisms, habitat loss and degradation remain the major threat to waterbirds in Australia. The ongoing pressure on water resources and developments of estuaries continue to cause decline of waterbirds, exacerbated by secondary threats including climate change, disease, hunting, pollution and disturbance. Hunting continues to have an impact, but it is relatively poorly modelled, requiring more investment by governments charged with its management. Effective conservation of Australian waterbirds and their wetland habitats depends on mitigating habitat loss and degradation, primarily dependent on political will not knowledge.
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Crowley, GM. "Late quaternary mangrove distribution in northern Australia." Australian Systematic Botany 9, no. 2 (1996): 219. http://dx.doi.org/10.1071/sb9960219.
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Although mangroves have long graced the north Australian coastline, stable sea levels required for the formation of extensive mangrove swamp forests have occurred only intermittently over the late Quaternary. Most ancestral mangrove swamps are likely to have been formed below present sea level. The only well-preserved deposits that have been described, developed on the present continental surface as sea level reached its present position in the early Holocene. Gradual upstream shifting of mangrove communities from about 8400 BP is recorded in sediments from the wet tropics, followed by the establishment of extensive Rhizophora forests over the newly drowned estuaries. More extensive Rhizophora swamps developed in the monsoon tropics where an earlier transitional phase has not been preserved. These 'big swamps' infilled over the next 1500–4500 years as sediments accumulated above the now stable sea level. The present mangrove estate, though more restricted, is fairly stable, with maintenance of mangrove forests in protected prograding bays and in estuaries kept open by adequate river flow. In the short term, mangroves may be threatened by human influences, but any change in climate leading to a gradual change in sea level should again provide conditions for expansion of mangrove habitats across northern Australia.
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Hirst, Alastair J. "Broad-scale environmental gradients among estuarine benthic macrofaunal assemblages of south-eastern Australia: implications for monitoring estuaries." Marine and Freshwater Research 55, no. 1 (2004): 79. http://dx.doi.org/10.1071/mf03011.
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The importance of abiotic factors in explaining patterns of estuarine benthic macrofaunal community structure was examined on a broad spatial scale across south-eastern Australia. Macrofaunal communities were surveyed using an Ekman grab and a modified epibenthic sled (dredge) at each sampling site: data for 24 environmental variables were also collected. Twenty-eight estuaries were sampled on a single occasion during late summer at three stratified locations within each estuary (upper, mid and lower). Macrofaunal community composition was best explained by a common environmental gradient summarising variation in both salinity and longitude. Hence, although the distribution of macrofaunal taxa can be clearly linked to changes in salinity, the geographical position of the sites along an east–west axis, rather than a generalised down-stream gradient, appears to best explain the data. This association was primarily linked to broad-scale changes in estuarine morphology across the geographical range of this survey. A sediment-based environmental gradient among grab samples, but not dredge samples, reflected the largely infaunal nature of the grab samples. In general, the present survey did not support the classification of estuarine assemblages on the basis of a range of physical parameters but, instead, emphasised the continuity of estuarine benthic macrofaunal community structure on a broad spatial scale.
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Smith, Kimberley A., and Iain M. Suthers. "Consistent timing of juvenile fish recruitment to seagrass beds within two Sydney estuaries." Marine and Freshwater Research 51, no. 8 (2000): 765. http://dx.doi.org/10.1071/mf99142.
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Recruitment patterns of juvenile Rhabdosargus sarba (Sparidae) and Pelates sexlineatus (Terapontidae) were examined by frequent (1–4 weeks) beach seining of seagrass beds in Sydney, south-east Australia. Two sites within each of two estuaries (Botany Bay and Pitt Water) were sampled for one year. One site within Botany Bay was sampled for 3 years. A total of 12 824 juveniles of R. sarba and 7037 juveniles of P. sexlineatus were collected. R. sarba recruited in 4 pulses during winter/spring, while P. sexlineatus recruited in 6 pulses during summer/autumn, and the timing of recruitment events was consistent among locations and years. P. sexlineatus recruitment coincided with new moons, but R. sarba recruitment dates were less precisely determined. Predictable annual recruitment patterns result in temporal partitioning of seagrass habitat between these two abundant estuarine species. Spatial differences in magnitude of recruitment events among sites reflected patterns of estuarine circulation.
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Petuch, Edward, David Berschauer, and David Waller. "A New Cowrie from the Estuaries of Northwestern Australia." Festivus 51, no. 2 (April 1, 2019): 81–87. http://dx.doi.org/10.54173/f512081.
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A new species of cowrie in the genus Erronea (Ipserronea) is described from the muddy coastal estuaries of King Sound, Western Australia, at the mouth of the Fitzroy River. The new cowrie, here named Erronea (Ipserronea) garyi n. sp., is the smallest-known member of its subgenus and inhabits oyster and Pinna beds on intertidal mud flats adjacent to mangrove jungles and river inlets. This new mudflat-dwelling dwarf cowrie is the fifth-known species in the subgenus Ipserronea
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Golding, C. J., R. J. Smernik, and G. F. Birch. "Characterisation of sedimentary organic matter from three south-eastern Australian estuaries using solid-state 13C-NMR techniques." Marine and Freshwater Research 55, no. 3 (2004): 285. http://dx.doi.org/10.1071/mf03167.
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Solid state 13C-nuclear magnetic resonance (NMR) spectroscopy was used to characterise sedimentary organic matter sampled from three estuaries on the central New South Wales coast (Australia). Cross polarisation (CP) and Bloch decay (BD) experiments were used to determine the chemical composition of the samples. These experiments indicated that, although the natural organic matter is predominately terrestrial in origin, the proportion of carbon existing as aromatic carbon, distinctive of vascular plants, decreases towards the mouth of the estuaries. This suggests that the relative contribution of terrestrial and marine source material largely defines the character of estuarine organic matter. Substantial amounts of charcoal were identified in sedimentary organic matter close to recent bushfire activity. Proton-spin relaxation editing (PSRE) was used to probe the physical structure of the sedimentary organic matter at the sub-micron scale. This technique showed that the organic matter was heterogeneous, providing support for a popular model of sedimentary organic matter structure. However, detailed interpretation of the domain structure of the organic matter was hindered by the presence of multiple components from both terrestrial and marine sources.
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Rustomji, Paul. "Flood and drought impacts on the opening regime of a wave-dominated estuary." Marine and Freshwater Research 58, no. 12 (2007): 1108. http://dx.doi.org/10.1071/mf07079.
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Wave-dominated estuaries are affected by floods generated in their hinterland catchments as well as marine tide and wave processes. The interaction of these terrestrial and marine influences controls the opening regime of the estuary. Despite the well documented environmental pressures on estuaries including elevated nutrient loadings and abstraction of river flows, little research concerning the variability and controls on estuary mouth opening regimes exists. From water level observations of Tuross Lake estuary in south-eastern Australia, the estuary’s recent opening regime is reconstructed and shown to vary significantly over time. Floodwaters fill the estuary and scour the estuary mouth, enhancing the exchange of marine water between the estuary and the ocean, which manifests as an increased tidal range within the estuary. Between floods, tide and wave activity caused aggradation of the estuary mouth such that the tidal range within the estuary declined by 0.5–0.7 mm per day as the mouth became more constricted. Under conditions of low river flow, high evaporative losses and seasonal reductions in ocean wave height, the estuary mouth can close completely. Using twentieth century streamflow estimates, it is shown that hydrologic variability is likely to have resulted in large variations in the estuary’s opening regime. Since 2000, there have been relatively few flood-driven scour events and this explains the relatively congested state of the current estuary mouth. Predicted hydrologic changes under enhanced atmospheric carbon dioxide concentrations are also likely to enhance the variability in the estuary’s opening regime.
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Zampatti, Brenton P., Christopher M. Bice, and Paul R. Jennings. "Temporal variability in fish assemblage structure and recruitment in a freshwater-deprived estuary: The Coorong, Australia." Marine and Freshwater Research 61, no. 11 (2010): 1298. http://dx.doi.org/10.1071/mf10024.
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River regulation can diminish freshwater flows to estuaries and compromise estuarine functionality. Understanding biotic responses to altered flow regimes is imperative to effectively manage aquatic ecosystems. The present study investigated temporal variation in fish assemblage structure and the recruitment of catadromous fish in the Coorong estuary at the terminus of the Murray River, in south-eastern Australia. Over the three-year study period, freshwater inflows to the estuary diminished and ultimately ceased, disconnecting freshwater and estuarine environments. It was hypothesised that these conditions would lead to (1) increases in estuarine salinities and concomitant changes in fish assemblage structure and abundance, and (2) decreased recruitment of catadromous fish. As freshwater inflow decreased, salinities immediately downstream of a series of tidal barrages increased from brackish to marine–hypersaline, species richness and diversity decreased, freshwater and diadromous species became less abundant and assemblages were increasingly characterised by marine species. Furthermore, the abundance of young-of-year catadromous fish decreased dramatically. Excessive regulation of freshwater inflows is resulting in the Coorong estuary resembling a marine embayment, leading to a loss in species diversity. We suggest, however, that even small volumes of freshwater may promote diversity in estuarine fish assemblages and some recruitment of catadromous species.
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Taylor, Matthew D. "Spatial and temporal patterns of habitat use by three estuarine species of mysid shrimp." Marine and Freshwater Research 59, no. 9 (2008): 792. http://dx.doi.org/10.1071/mf07247.
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The mysids Rhopalopthalmus egregius, Haplostylus dakini and Doxomysis australiensis are abundant yet unstudied omnivorous crustaceans in Australian estuaries. Habitat use and population dynamics were investigated for these species over spring and summer in the Tweed River, Australia, to explore their ecological role in estuarine ecosystems. Overall, mysids were concentrated in shallow unvegetated and deep unvegetated estuarine habitats. H. dakini were most abundant in shallow and deep bare habitats at night, whereas R. egregius were most abundant in deep bare habitats during the night. D. australiensis were present across all habitats in the night, but negligible numbers were present during the day. Significantly greater numbers of R. egregius and D. australiensis were sampled during the new moon, compared with the full moon. Significantly larger R. egregius and D. australiensis individuals were present in benthic habitats at night, indicating possible partitioning of habitat for juvenile and adult subpopulations. Adaptive foraging strategies and habitat use facilitates the coexistence of sympatric mysid species, H. dakini and R. egregius, and within-species habitat partitioning allowed juvenile R. egregius to avoid interaction with adult R. egregius. The observed dynamics minimize inter- and intra-specific predation between mysids, and by other predators, while optimizing access to key trophic resources.
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Kriwoken, Lorne K., and Paul Hedge. "Exotic species and estuaries: managing Spartina anglica in Tasmania, Australia." Ocean & Coastal Management 43, no. 7 (July 2000): 573–84. http://dx.doi.org/10.1016/s0964-5691(00)00047-8.
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Russell, D. J., and A. J. McDougall. "Movement and juvenile recruitment of mangrove jack, Lutjanus argentimaculatus (Forsskål), in northern Australia." Marine and Freshwater Research 56, no. 4 (2005): 465. http://dx.doi.org/10.1071/mf04222.
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Lutjanus argentimaculatus, tagged and released in coastal rivers and estuaries, were found to have made inter- and intra-riverine, coastal and offshore movements. A small proportion of the recaptures made offshore movements to reef habitats of up to 315 km and these recaptures were fish that were at liberty, on average, more than twice as long as those fish that had made intra-riverine movements. Most juvenile fish <400-mm length to caudal fork (LCF) resident in rivers were recaptured less than a kilometre from where they were released. The proportion of fish making sizeable movements increased with increasing recapture size, with about of 20% of larger fish (400–500-mm LCF) making offshore, inter-riverine or coastal movements. Larger fish were primarily caught offshore, whereas smaller fish <~338-mm LCF were exclusively caught in estuarine and freshwater habitats. Recruitment of juveniles into estuarine and lower freshwater riverine habitats occurred from about February. There was temporal variability of recruitment of mangrove jack into some river systems and their relative abundance within the river system was inversely proportional to the distance from the sea. Overfishing of juveniles when they are concentrated in inshore areas could have adverse implications for mangrove jack stocks.
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Lenanton, R. C. J., and I. C. Potter. "Contribution of Estuaries to Commercial Fisheries in Temperate Western Australia and the Concept of Estuarine Dependence." Estuaries 10, no. 1 (March 1987): 28. http://dx.doi.org/10.2307/1352022.
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Meynecke, J. O. "Coastal habitat connectivity ? implications for declared fish habitat networks in Queensland, Australia." Pacific Conservation Biology 15, no. 2 (2009): 96. http://dx.doi.org/10.1071/pc090096.
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Estuaries are widely recognized as key habitats supporting nearshore secondary production and catch of commercial fisheries. In Queensland, some of these coastal marine habitats are protected by the declared fish habitat programme run by the Department of Primary Industries and Fisheries. Expected environmental changes for Australian estuarine systems include reduced freshwater flow, increased sedimentation and with them, a loss of connectivity. At present, the relationship between the protected declared fish habitat and habitat connectivity remains unknown. By comparing long term coastal fish catch data with geomorphic characteristics of coastal habitats structural connectivity was previously identified as a potential driver of commercial fish catch in Queensland. An ecology landscape approach was used for this study to identify potential fish habitat hotspots along the coastline of Queensland thus allowing better defined networks of declared fish habitats. A comparison between this approach and the current declared fish habitats demonstrated potential deficits and provided important insights for fisheries management. Declared fish habitats should be placed in coastal habitats with high structural connectivity to ensure sustainability of fisheries in light of environmental changes.
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Woodroffe, C. D. "Mangrove response to sea level rise: palaeoecological insights from macrotidal systems in northern Australia." Marine and Freshwater Research 69, no. 6 (2018): 917. http://dx.doi.org/10.1071/mf17252.
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Accelerated sea-level rise threatens coastal wetlands; it is unclear whether sediment accretion beneath mangroves will be sufficient to keep pace. A conceptual framework, used to describe the response of reefs, can also be applied to mangroves, discriminating drowning or back-stepping with rapid rise from keep-up or catch-up under moderate rates. In macrotidal estuaries of northern Australia, different mangrove species grow across particular elevation ranges and accretion rates decrease with tidal elevation. Palaeoecological reconstructions, from drilling, dating and pollen analysis, record mangrove distribution over past millennia. Estuarine plains are underlain by a vertically continuous stratigraphy of muds, implying continuity of widespread ‘big swamp’ mangrove forests during decelerating stages of post-glacial sea-level rise c. 7000 years ago. In contrast, on higher-energy open coasts, mangroves back-stepped, but re-established as the shoreline prograded when the nearshore built to suitable elevation: a catch-up mode. These results demonstrate that mangrove response to sea-level rise has varied, determined by the availability of sediment and the oceanographic processes by which it is redistributed. How mangrove forests adjust in future will also vary as a function of local topography and sediment availability. Extensive plains flanking estuarine systems are particularly vulnerable to tidal creek extension and saline incursion under future higher sea levels.
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Bruce, L. C., P. L. M. Cook, I. Teakle, and M. R. Hipsey. "Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia." Hydrology and Earth System Sciences Discussions 10, no. 7 (July 26, 2013): 9799–845. http://dx.doi.org/10.5194/hessd-10-9799-2013.
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Abstract. Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM) to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74). The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends). The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65) increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement of oxygen depletion, temperature was critical in determining the extent of hypoxia and anoxia in the estuary. These findings highlight the importance of how seasonal changes in flow events and environmental flow management can impact on estuarine oxygen depletion in a warming climate. This study provides an improved understanding of the controls on hypoxia and anoxia in riverine estuaries, which is essential to support improved prediction of nutrient dynamics and ecological heath.
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Radke, L. C., I. P. Prosser, M. Robb, B. Brooke, D. Fredericks, G. B. Douglas, and J. Skemstad. "The relationship between sediment and water quality, and riverine sediment loads in the wave-dominated estuaries of south-west Western Australia." Marine and Freshwater Research 55, no. 6 (2004): 581. http://dx.doi.org/10.1071/mf04044.
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We examine surface sediment and water column total nutrient and chlorophyll a concentrations for 12 estuaries with average water depths <4 m, and calculated sediment loads ranging from 0.2 to 10.8 kg m−2 year−1. Sediment total nitrogen, phosphorus and organic carbon concentrations vary inversely with sediment loads due to: (i) the influx of more mineral-rich sediment into the estuaries; and (ii) increasing sediment sulfidation. Sediment total organic carbon (TOC) : total sulfur (TS) and TS : Fe(II) ratios correlated to sediment loads because enhanced sedimentation increases burial, hence the importance of sulfate reduction in organic matter degradation. Curvilinear relationships were found between a weathering index and organic matter δ13C in sediment, and sediment load. The rising phase of the curve (increasing weathering, lighter isotopic values) at low to intermediate loads relates to soil erosion, whereas regolith or bedrock erosion probably explains the declining phase of the curve (decreasing weathering, heavier isotopic values) at higher sediment loads. The pattern of change for water column total nutrients (nitrogen and phosphorus) with sediment loads is similar to that of the weathering index. Most water quality problems occur in association with soil erosion, and at sediment loads that are intermediate for the estuaries studied. Limited evidence is presented that flushing can moderate the impact of sediment loads upon the estuaries.
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Amaral, Valter, Henrique N. Cabral, and Melanie J. Bishop. "Effect of runoff from acid-sulfate soils on pneumatophores of the grey mangrove, Avicennia marina." Marine and Freshwater Research 62, no. 8 (2011): 974. http://dx.doi.org/10.1071/mf11003.
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Runoff from acid-sulfate soils (ASS) is increasingly threatening the structure and function of estuarine ecosystems worldwide. Along the eastern coast of Australia, sulfuric acid is known to affect the growth and survival of mangrove saplings; however, impacts of ASS runoff on the structure and function of established mangrove trees are unclear. Pneumatophores, the aerial roots produced by some species of mangrove, are critical sites of gas exchange, allowing these species to persist in waterlogged soils. They also provide physical structure in estuarine sediments, facilitating communities of algae, invertebrates and, at high tide, fish. We tested the hypotheses that Avicennia marina (Forsk.) Vierh. pneumatophores would be less abundant, shorter, thinner and weaker close to major ASS outflow drains. Sampling at sites close to and away from drains within each of two estuaries of New South Wales, Australia, showed no effect of exposure to runoff on pneumatophore density or thickness. Pneumatophores were, however, shorter (~2 cm) and weaker (up to two-fold) at ASS-affected than reference sites. Although the reduced length and strength of pneumatophores at acidified sites may limit the number of epifaunal molluscs they can support, the persistence of dense pneumatophores indicates that the capacity to benefit invertebrates and fish remains.
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Nicholson, Geoff, Gregory P. Jenkins, John Sherwood, and Andy Longmore. "Physical environmental conditions, spawning and early-life stages of an estuarine fish: climate change implications for recruitment in intermittently open estuaries." Marine and Freshwater Research 59, no. 8 (2008): 735. http://dx.doi.org/10.1071/mf07197.
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Significant variation in the egg and larval survival and juvenile recruitment of estuarine fishes has been linked to fluctuating environmental conditions. This present study compared the distribution and abundance of black bream (Acanthopagrus butcheri) eggs and yolk-sac larvae between two microtidal estuaries of different flow regimes, where the riverine flow into the Glenelg estuary was around eight times the flow volume into the Hopkins estuary. Samples were collected monthly from September to November at sites along each estuary where vertical profiles of temperature, salinity and dissolved oxygen (DO) were measured, and vertically stratified sampling of black bream eggs and yolk-sac larvae was conducted using a Schindler sampler. Salt wedge formation was apparent in both estuaries, with significant de-oxygenation of deeper, saline waters. Eggs occurred in a wide range of DO levels but yolk-sac larvae were less common at the lowest levels. Most eggs and yolk-sac larvae were collected in salinities greater than 10. Results suggested that egg mortality was higher in the Hopkins than the Glenelg estuary, which may be associated with the hypoxic conditions characteristic of low-flow conditions. The results have significant implications in terms of climate change that is predicted to lead to warmer, drier conditions in south-eastern Australia, potentially increasing stratification and subsequent hypoxic zones.
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Birch, Gavin F., and Marco A. Olmos. "Sediment-bound heavy metals as indicators of human influence and biological risk in coastal water bodies." ICES Journal of Marine Science 65, no. 8 (September 15, 2008): 1407–13. http://dx.doi.org/10.1093/icesjms/fsn139.
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AbstractBirch, G. F., and Olmos, M. A. 2008. Sediment-bound heavy metals as indicators of human influence and biological risk in coastal water bodies. – ICES Journal of Marine Science, 65: 1407–1413. Currently, many institutions are conducting or planning large, regional-scale ecosystem assessments of estuarine health. A full, integrated assessment of these environments requires a large suite of biological, physical, and chemical indicators, including sedimentary chemistry, ecotoxicology, benthic community structure, and bioaccumulation. This commitment is beyond the capacity of most organizations, and a simpler approach is required to accommodate limited financial resources. A case is made for the use of sedimentary heavy metals as an easy and inexpensive indicator. The advantages are that sediments identify the “pristine” condition and give baseline information against which future management strategies may be benchmarked, and that they differentiate solely human-induced change from natural variation. Sediment indicators in depositional environments are also less dynamic than those associated with water and biota. Our objective is to demonstrate that sediment-bound heavy metals data provide the spatial extent and magnitude of chemical change, as well as the risk of biological stress attributable to contamination in estuarine ecosystems. An assessment of this scheme involving seven New South Wales (Australia) estuaries suggests that sedimentary heavy-metal indicators used in a weight-of-evidence approach, with data collected during the recent Australian National Land and Water Resources Audit, enhances estuarine condition assessment.
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McLean, Errol J., and Jon B. Hinwood. "APPLICATION OF A SIMPLE HYDRODYNAMIC MODEL TO ESTUARY ENTRANCE." Coastal Engineering Proceedings 1, no. 32 (January 30, 2011): 42. http://dx.doi.org/10.9753/icce.v32.management.42.
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Tidal inlets which link a tidal basin to the sea via a constricted entrance are common on the south-east Australian coast. Closure, or even significant constriction, raises water levels but restricts tidal range within the basin, while open entrances provide regular and significant tidal exchange with the ocean. A rapid assessment procedure with minimal data requirements has been shown to be informative for monitoring and a useful component of any Decision Support System set up as part of a management structure. Such a system is presented in this paper. It is based on one permanent water level gauge inside the inlet plus the use of a simple, first-order hydrodynamic model to relate the tide range, mean water level and river flow to the inlet cross sectional area. The method is tested against data from the
Snowy River Estuary in south-eastern Australia but would be suitable over a range of estuaries. In addition, the framework presented can also provide a mechanism to explore conditions over the range of expected data, thus allowing better selection of model schematization and runs in estuarine systems where the use of 2 or 3D modeling can be justified.
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Hinwood, Jon, and Errol McLean. "STABILITY OF SMALL BARRIER ESTUARIES: FIRST PASS ASSESSMENT USING PUBLIC DATA AND ATTRACTOR MODELLING." Coastal Engineering Proceedings, no. 36v (December 31, 2020): 64. http://dx.doi.org/10.9753/icce.v36v.papers.64.
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Small barrier estuaries are common in temperate latitudes where catchment runoff is small. The entrance state controls the tidal exchange and hence the salinity regime and flushing. To aid the study and management of these estuaries, predictions of the stability and future evolution of the estuary entrance must be made. This paper demonstrates the application of the attractor method to determine the stability of a wide sample of estuaries on the south-eastern coast of Australia, using only data available in broad-based public data bases. The method uses a simple hydrodynamic-sediment balance model, run for thousands of scenarios and thousands of tide cycles to identify the long-term dynamic equilibria - the attractors. The model predictions are shown to match stability data in the data bases and to provide realistic predictions of the entrance evolution. The results have direct applicability to high-level assessment of coastal assets and to optimal selection of model scenarios for more detailed modelling of any selected estuary.
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Sloss, Craig R., Colin V. Murray-Wallace, and Brian G. Jones. "Aminostratigraphy of Two Holocene Wave-Dominated Barrier Estuaries in Southeastern Australia." Journal of Coastal Research 221 (January 2006): 113–36. http://dx.doi.org/10.2112/05a-0010.1.
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