Academic literature on the topic 'Lake Macquarie'

Increasing urbanisation of coastal areas is leading to impacts on coastal lakes which decrease their amenity for recreation and tourism. Runoff and wastewater discharge cause siltation, impact seagrass beds and change the characteristics of open waters, affecting boating, swimming, fishing and the aesthetic quality of the locale. Management of urban development and wastewater disposal is required to minimise sedimentation and nutrient enrichment. This could include development restrictions, runoff controls and a strategy for wastewater treatment and discharge. The catchment of Lake Macquarie, a marine coastal lake, has been progressively urbanised since 1945. Urbanisation, through increased stormwater runoff and point source discharges, has caused a major impact on the lake in terms of sedimentation and nutrient enrichment. Losses of lake area and navigable waters have occurred. Accompanying problems include changes in the distribution of seagrass beds and nuisance growths of benthic algae. Since the 1950's, dry weather nutrient concentrations have increased and mean water clarity has decreased. Severe problems, as observed in other New South Wales coastal lakes, for example benthic algae in Lake Illawarra and Tuggerah Lakes, have not yet developed. Because of the lead time taken to implement policies and controls, trends should be identified and policies developed now so as to avoid nutrient buildup and development of sustained problems.

The gonadal development, reproductive cycle and growth of Macquarie perch, Macquaria australasica Cuvier, in Lake Dartmouth and selected tributaries of the Murray–Darling River Basin in south-eastern Australia were evaluated. Gonadosomatic index (GSI) and histological analysis were used to determine gonadal development and age and size at first maturity in the resident Lake Dartmouth population. GSI analysis was also used to determine age and size of Macquarie perch at first maturity in the inflowing Mitta Mitta River and other riverine populations within the Goulburn River catchment. Males appeared slightly smaller at first spawning than females at all sites; both sexes were fully mature at four years of age. Differences in size at first maturity were found between the lake and river populations; both males and females of river populations tended to mature at a much smaller size than the fish resident in the lake. Spawning occurred around November. Ovarian and testicular development in this species follows a pattern similar to that of other native Australian percichthyids. The implications for management of recreational fisheries based on minimum size regulations is discussed in relation to site-specific differences in growth rates and size of first maturity of fish.

The composition of the diet of Macquarie perch changed markedly during the various stages of rising and falling water-level during the initial filling phase of Lake Dartmouth, an impoundment formed by the construction of Dartmouth Dam on the Mitta Mitta River in north-eastern Victoria. Macquarie perch fed on typical river-dwelling organisms from inflowing rivers, on terrestrial organisms that became displaced as the water-level rose, and on typical still-water or sluggish-water organisms, which were extremely abundant in the newly created lake. The relative proportions of several of these food types in the diet varied depending on whether the water-level was rising or falling. Macquarie perch appear to have adapted well to the changing food supply in the lake, and have included in their diet several food types that they would not normally have encountered in their natural riverine habitat.

Rapid increases in native riverine fish populations associated with trophic upsurge immediately following reservoir construction are well documented. Repeated upsurge periods and extended benefits to populations are, however, less understood. We used sclerochronology to investigate fish growth and netting surveys to estimate recruitment and abundance of a lacustrine population of an Australian riverine fish, the Macquarie perch (Macquaria australasica) in Lake Dartmouth. Record low inflows from 1997 to 2008 caused the reservoir to shrink to its lowest volume since construction. Refilling began in 2008, reaching 99% capacity in 2013. We hypothesized that fish growth, recruitment, and abundance would increase in response to the refilling of the lake, reproducing a similar response to the initial filling period. Our findings supported this hypothesis. Macquarie perch growth, recruitment, and abundance were enhanced during the refilling of Lake Dartmouth. Growth, best explained by the effects of dam height, change in dam height, temperature (and their interactions), and recruitment, were highest during the first years of refilling when lake levels and temperatures were low. We propose one or a combination of varying levels of intraspecific competition (low during initial filling and high following population expansion) and improved riverine conditions for reproductive success as the most plausible explanation. Our results suggest extended periods of low lake levels followed by rapid inundation events are likely to enhance recruitment and population growth opportunities for this species. While reservoir construction in general impacts negatively on native fish populations, the potential to offset these impacts for conservation management purposes should be considered.

AbstractThis study is the first published survey of diatom-environment relationships on sub-Antarctic Macquarie Island. Fifty-eight sites in 50 coastal and inland lakes were sampled for benthic diatoms and water chemistry. 208 diatom species from 34 genera were identified. Multivariate analyses indicated that the lakes were distributed along nutrient and conductivity gradients. Conductivity, pH, phosphate (SRP), silicate and temperature all explained independent portions of the variance in the diatom data. Transfer functions provide a quantitative basis for palaeolimnological studies of past climate change and human impacts, and can be used to establish baseline conditions for assessing the impacts of recent climate change and the introduction of non-native plants and animals. Statistically robust diatom transfer functions for conductivity, phosphate and silicate were developed, while pH and temperature transfer functions performed less well. The lower predictive abilities of the pH and temperature transfer functions probably reflect the broad pH tolerance range of diatoms on Macquarie Island and uneven distribution of lakes along the temperature gradient. This study contributes to understanding the current ecological distribution of Macquarie Island diatoms and provides transfer functions that will be applied in studies of diatoms in lake sediment cores to quantitatively reconstruct past environmental changes.

The Eastern Grey Kangaroo Macropus giganteus originally extended from the River Forth in the northwest to the east coast and south to North West Bay. It occurred on both sides of the Derwent River upstream beyond New Norfolk and into the central highlands along the Ouse and Shannon Rivers to the Great Lake, Lake Echo and Arthur's Lakes. Its highest density was probably in the coastal areas of the northeast and in the Norfolk Plains areas of the Macquarie and South Esk Rivers. Its present range comprises islands within that original range, augmented by a few populations established by translocation.

Norovirus is an important human pathogen that is now recognized as the leading cause of acute gastroenteritis globally. Six viral genogroups have been described, although only genogroups GI, GII, and GIV are known to infect humans, with the GII viruses most commonly identified in both outbreak and sporadic settings. In contrast, infections by GIV viruses are rarely reported, and their overall prevalence in the community is unknown. Here, we report the complete genome sequence of the human GIV.1 strain Lake Macquarie virus, which caused two linked outbreaks of acute gastroenteritis in aged-care facilities in the Hunter region of New South Wales, Australia. The Lake Macquarie virus genome was 7,527 nucleotides (nt) in length and shared highest identity (70%) with the recently completed feline GIV.2 virus genome.

The genetic structure of M. bennettae populations from six locations on the east coast of Australia was investigated using starch-gel electrophoresis. Eight polymorphic loci (fumarate hydratase, glucose- 6-phosphate isomerase, malate dehydrogenase-1 and -2, mannose-6-phosphate isomerase, octanol dehydrogenase, phosphogluconate dehydrogenase and phosphoglucomutase) were examined. All loci over the six sites were in Hardy-Weinberg equilibrium. Although low levels of variation typical of penaeid prawns were found, the contingency Χ2 analysis of allele frequencies over all locations revealed considerable genetic heterogeneity. However, pairwise comparisons of adjacent locations showed that most of this genetic heterogeneity was largely attributable to the Moreton Bay-Lake Macquarie comparison. These two locations are the most widely separated adjacent sample sites. Replicate samples from 1982 and 1983 revealed consistency in allele frequencies at Moreton Bay and at Lake Macquarie. These results confirm previously reported genetic heterogeneity between Queensland and New South Wales populations of M. bennettae, but they do not support the report that nearby populations in both Queensland and New South Wales are also heterogeneous.

In response to concern that excessive macroalgal growth and accumulation was occurring in some inshore areas of Lake Macquarie, the distribution, abundance and seasonality of macroalgae was investigated in relation to nutrient input and power station cooling water. Macroalgal dry weight biomass was measured at ten sites on a monthly basis for two years, with an analysis of community structure conducted using Multi-Dimensional Scaling. The macroalgal community in Lake Macquarie was typical of those found in other New South Wales coastal lagoons, exhibiting considerable spatial and temporal variation. A close similarity was observed in macroalgal community structure at sites affected by urban nutrient input, these being characterised by a high biomass often attributable to only one or two species. These nuisance macroalgae were mostly green algae, which were almost entirely absent from other sites. Biomass at sites affected by urban nutrient input was generally within the range documented for eutrophic estuaries elsewhere. Analysis of macroalgal community structure showed no evidence of large-scale changes macroalgal communities attributable to the effects of power station cooling water except within 500m of the outfall. At sites affected by a 1-2??C temperature increase, community structure and the magnitude of the biomass were similar to sites deemed as being relatively free of human impact. A reduction in species diversity occurred only within the immediate discharge zone, where water temperatures were approximately 6??C above ambient temperatures. Excessive growth of nuisance macroalgal species was not observed at any of the sites influenced by power station cooling water. There were no distinct patterns in seasonality of macroalgal growth in this study, though the greatest biomass appeared to occur in spring. The irregular temporal variation in macroalgal growth suggests that the most significant factors affecting growth occur on a time scale of weeks to months. It is therefore likely nutrient input to the nearshore through surface runoff is an important influence on the distribution and abundance of macroalgae in Lake Macquarie. This emphasises the need to reduce nitrogen and phosphorus input from urban sources in Lake management.

Thesis (Ph. D.)--University of Sydney, 1999.
Title from title screen (viewed Apr. 21, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Dept. of Chemical Engineering, Graduate School of Engineering. Includes bibliography. Also available in print form.

THESIS ORGANISATION This thesis is organised into nine chapters that include seven international and national publications (six accepted and one submitted for publication). The initial overview chapter outlines the justification and direction for this thesis. With the exception of chapter 8 (accepted for publication on the 1st May 2005); all chapters are exact duplicates of published articles in international and national refereed journals (chapters 2 to 7). The initial chapters (2 and 3) presents research findings using a marine fish species, mullet (Mugil cephalus), to measure trace metal bioavailability in Lake Macquarie, NSW Australia. While subsequent chapters (4 to 8) are presenting research under taken to improve the understanding of arsenic cycling in marine and estuarine environments. The final chapter (chapter 9) is a synopsis of the major findings presented in this thesis. Due to the publication nature of this thesis, an unavoidable degree of replication exists within chapters (publications).

ABSTRACT This work examined the role of micro-organisms in the biogeochemical cycling of selenium within the benthic ecosystem of Lake Macquarie, a coastal lake in New South Wales with a history of anthropogenic heavy metal contamination. Certain micro-organisms possess the ability to oxidise or reduce selenium (Fleming and Alexander, 1973; Doran and Alexander, 1977), and microbial volatilisation of selenium from contaminated sediments and soils utilising naturally-occurring microflora has been shown in overseas research (Thompson-Eagle and Frankenberger, 1992) to be a potentially effective remediation strategy. In examining the impact of micro-organisms upon the oxidation state of selenium in Lake Macquarie sediments, this work also investigated and characterised selenium (and heavy metal) concentrations, speciation and geochemical phase associations (an indicator of potential bioavailability) in the sediments. Seven distinct bacterial species indigenous to Lake Macquarie were identified in this work with the ability to reduce selenium as selenite to elemental selenium, and selenium as selenate to organic forms of selenium, including volatile methylated selenium compounds. Metabolic parameters calculated for these organisms compared favourably with those reported in the literature by other researchers. Mixed populations of sediment micro-organisms were also isolated and studied in this work for their selenite and selenate reduction abilities. Total reduction of added selenite at levels up to 100 mg/L was recorded for a number of the organisms studied in this work. A maximum specific uptake rate for selenite of 3040 mgSe(IV).(gcells)-1.(h)-1 for one isolate (Shewanella putrefaciens) was determined, exceeding rates reported in the literature by other authors. Use of the indigenous micro-organisms from Lake Macquarie for the bioremediation of selenium containing waste streams was also examined in this work and selenium reduction in an immobilised cell reactor was demonstrated with such organisms. Concentrations, speciation, sediment core profiles and geochemical phase associations for selenium were determined for sediment samples collected at a variety of sites throughout Lake Macquarie and from Wyee Creek, a selenium-impacted fluvial input to the lake. The maximum concentration of selenium obtained in this work for the lake proper was 4.04 mg/kg, considerably lower than values reported over a decade ago (Batley, 1987) but consistent with reported reductions of selenium input into the lake from the lead-zinc smelter. Selective extraction methodology (Tessier et al. and BCR methods) studied geochemical phase association of selenium in Lake Macquarie sediments and found up to 44% of selenium was in bioavailable forms. Of interest and environmental concern was levels of selenium found in sediments of Wyee Creek, which previously received overflows from the ash dam associated with the Vales Point Power Station. Sediment selenium levels of up to 300 mg/kg were determined for this creek. These were an order of magnitude or more greater than those recorded for the lake itself and are of concern as to the potential impact on benthic organisms and those animals, including humans, who consume them. While this work can only provide a 'snapshot' of conditions within Lake Macquarie at the time of the sampling events recorded herein, it does make several important contributions to the understanding of selenium biogeochemistry in Lake Macquarie. These include: presentation of the hypothesis that selenium levels in surficial sediments being deposited in the north of the lake have decreased in recent years as a result of selenium reduction measures undertaken by the lead-zinc smelter; determination that up to 44% of selenium in surficial sediments from the lake is associated with sediment phases in which selenium has the potential to become remobilized and hence possibly bioavailable; and documentation of selenium concentrations in Wyee Creek, identifying the area as having selenium concentrations an order of magnitude or more greater than the lake itself. Concerning the role played by microorganisms in the biogeochemical cycling of selenium in Lake Macquarie, this work has: identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenite to lower oxidation states; identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenate to lower oxidation states; identified volatile methylated selenium compounds in the headspace gases of microorganisms reducing selenate; determined Minimum Inhibitory Concentrations for selenate and selenite for organisms isolated from Lake Macquarie; identified casein hydrolysate as a preferred carbon source for selenium reducing microorganisms from Lake Macquarie; and demonstrated that bioremediation of selenium contaminated waste streams using indigenous organisms from Lake Macquarie is feasible on the laboratory scale. Further research areas suggested by this work include: additional investigations of elevated selenium levels in Wyee Creek sediments; determination of the role of microbes in in-situ selenium reduction; and optimisation of selenium biotreatment/bioremediation of selenium-containing waste streams and sediments. In summary, this work, in rejecting the null hypothesis that the oxidation states of selenium in sediments from Lake Macquarie, NSW, are independent of microbial activity and accepting the alternate hypothesis that these oxidation states are not independent of microbial activity, contributes to the understanding of the role of microorganisms in the biogeochemical cycling of selenium, having applicability to both the specific ecosystem of Lake Macquarie, NSW, and also to selenium cycling in the environment in general. In addition, this work has identified selenium contamination in Wyee Creek, one of the fluvial inputs to Lake Macquarie, which was previously been undocumented in the literature and which may pose significant potential risk to humans and the ecosystem due to sediment selenium levels one or more orders of magnitude higher than those recorded in the lake itself. Finally, this work has also identified a number of microorganisms indigenous to Lake Macquarie with the ability to reduce selenium from toxic, mobile forms to less toxic, immobile or volatile forms, and these organisms have been shown to have the potential for use in treatment of selenium contaminated waste streams and also in the bioremediation of selenium-contaminated sediments.

ABSTRACT This work examined the role of micro-organisms in the biogeochemical cycling of selenium within the benthic ecosystem of Lake Macquarie, a coastal lake in New South Wales with a history of anthropogenic heavy metal contamination. Certain micro-organisms possess the ability to oxidise or reduce selenium (Fleming and Alexander, 1973; Doran and Alexander, 1977), and microbial volatilisation of selenium from contaminated sediments and soils utilising naturally-occurring microflora has been shown in overseas research (Thompson-Eagle and Frankenberger, 1992) to be a potentially effective remediation strategy. In examining the impact of micro-organisms upon the oxidation state of selenium in Lake Macquarie sediments, this work also investigated and characterised selenium (and heavy metal) concentrations, speciation and geochemical phase associations (an indicator of potential bioavailability) in the sediments. Seven distinct bacterial species indigenous to Lake Macquarie were identified in this work with the ability to reduce selenium as selenite to elemental selenium, and selenium as selenate to organic forms of selenium, including volatile methylated selenium compounds. Metabolic parameters calculated for these organisms compared favourably with those reported in the literature by other researchers. Mixed populations of sediment micro-organisms were also isolated and studied in this work for their selenite and selenate reduction abilities. Total reduction of added selenite at levels up to 100 mg/L was recorded for a number of the organisms studied in this work. A maximum specific uptake rate for selenite of 3040 mgSe(IV).(gcells)-1.(h)-1 for one isolate (Shewanella putrefaciens) was determined, exceeding rates reported in the literature by other authors. Use of the indigenous micro-organisms from Lake Macquarie for the bioremediation of selenium containing waste streams was also examined in this work and selenium reduction in an immobilised cell reactor was demonstrated with such organisms. Concentrations, speciation, sediment core profiles and geochemical phase associations for selenium were determined for sediment samples collected at a variety of sites throughout Lake Macquarie and from Wyee Creek, a selenium-impacted fluvial input to the lake. The maximum concentration of selenium obtained in this work for the lake proper was 4.04 mg/kg, considerably lower than values reported over a decade ago (Batley, 1987) but consistent with reported reductions of selenium input into the lake from the lead-zinc smelter. Selective extraction methodology (Tessier et al. and BCR methods) studied geochemical phase association of selenium in Lake Macquarie sediments and found up to 44% of selenium was in bioavailable forms. Of interest and environmental concern was levels of selenium found in sediments of Wyee Creek, which previously received overflows from the ash dam associated with the Vales Point Power Station. Sediment selenium levels of up to 300 mg/kg were determined for this creek. These were an order of magnitude or more greater than those recorded for the lake itself and are of concern as to the potential impact on benthic organisms and those animals, including humans, who consume them. While this work can only provide a 'snapshot' of conditions within Lake Macquarie at the time of the sampling events recorded herein, it does make several important contributions to the understanding of selenium biogeochemistry in Lake Macquarie. These include: presentation of the hypothesis that selenium levels in surficial sediments being deposited in the north of the lake have decreased in recent years as a result of selenium reduction measures undertaken by the lead-zinc smelter; determination that up to 44% of selenium in surficial sediments from the lake is associated with sediment phases in which selenium has the potential to become remobilized and hence possibly bioavailable; and documentation of selenium concentrations in Wyee Creek, identifying the area as having selenium concentrations an order of magnitude or more greater than the lake itself. Concerning the role played by microorganisms in the biogeochemical cycling of selenium in Lake Macquarie, this work has: identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenite to lower oxidation states; identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenate to lower oxidation states; identified volatile methylated selenium compounds in the headspace gases of microorganisms reducing selenate; determined Minimum Inhibitory Concentrations for selenate and selenite for organisms isolated from Lake Macquarie; identified casein hydrolysate as a preferred carbon source for selenium reducing microorganisms from Lake Macquarie; and demonstrated that bioremediation of selenium contaminated waste streams using indigenous organisms from Lake Macquarie is feasible on the laboratory scale. Further research areas suggested by this work include: additional investigations of elevated selenium levels in Wyee Creek sediments; determination of the role of microbes in in-situ selenium reduction; and optimisation of selenium biotreatment/bioremediation of selenium-containing waste streams and sediments. In summary, this work, in rejecting the null hypothesis that the oxidation states of selenium in sediments from Lake Macquarie, NSW, are independent of microbial activity and accepting the alternate hypothesis that these oxidation states are not independent of microbial activity, contributes to the understanding of the role of microorganisms in the biogeochemical cycling of selenium, having applicability to both the specific ecosystem of Lake Macquarie, NSW, and also to selenium cycling in the environment in general. In addition, this work has identified selenium contamination in Wyee Creek, one of the fluvial inputs to Lake Macquarie, which was previously been undocumented in the literature and which may pose significant potential risk to humans and the ecosystem due to sediment selenium levels one or more orders of magnitude higher than those recorded in the lake itself. Finally, this work has also identified a number of microorganisms indigenous to Lake Macquarie with the ability to reduce selenium from toxic, mobile forms to less toxic, immobile or volatile forms, and these organisms have been shown to have the potential for use in treatment of selenium contaminated waste streams and also in the bioremediation of selenium-contaminated sediments.

Scyphozoans of the genus Cassiopea are notable for their unusual benthic habitat of lying upside-down with their exumbrella resting on the substrate and oral arms facing upwards, resulting in their common name “upside-down jellyfish”. Cassiopea are model examples of an invasive species that have been historically confused because of their taxonomic ambiguity and can have significant economic and environmental consequences as their blooms are known to impact fisheries, tourism, and trophic structures. Cassiopea were first reported in temperate Lake Macquarie, New South Wales, in 2017, though historically these jellyfish have a more northern tropical distribution in Eastern Australia. This project aims to provide baseline information on the identification and presence of Cassiopea in Lake Macquarie and inform potential management strategies. This study used a genetic analysis to confirm two species of Cassiopea are expanding their range down the east coast of Australia, with a focus on C. xamachana, the species occurring in Lake Macquarie. A morphometric analysis identified the features that can be used to distinguish these species, and these results combined with the genetic analysis confirmed that C. maremetens, described in 2010 from southern Queensland, is a junior synonym of C. xamachana. Additionally, the results from this study confirm that Cassiopea abundance peaks during Austral Autumn and Winter, before experiencing a population crash in August. This appears to be controlled by temperature and turbidity, but their density and distribution is expected to increase with climate change. Additionally, no polyps have been found in the area and only females have been recorded, suggesting there was only one invasion event into Lake Macquarie, and since then, the polyps have been asexually reproducing. As a result, long-term monitoring is recommended and this study demonstrates that drones are a precise and efficient method for doing this.

This study examines the occurrence, distribution and storage of selenium in seagrass communities of Lake Macquarie, which is a heavily industrialised area of NSW, where notably high trace metal concentrations have been reported previously. Initially a suite of organisms was collected from a seagrass bed (Zostera capricornia) in the southeastern section of the lake to investigate the bioaccumulation and biomagnification of selenium. All organisms contained selenium, with sediment-dwelling organisms containing the highest Se concentrations. No consistent pattern of significant Se-metal correlations with Cu, Zn and Cd was found. Biomagnification of Se was evident, as concentrations increased from sediments and water to flora (algae and seagrass) to bivalves to Crustacea. However, this trend was not continued to the higher trophic groups of invertebrate predators and teleost fish. The bivalve Anadara trapezia was further studied. Intrinsic and extrinsic factors affecting the accumulation of Se were examined. Gender and mass were assessed in a single day study, followed by a temporal investigation of the effect of gender, reproductive cycle, temperature and salinity on Se accumulation. Gender had no effect on the accumulation of Se in A. trapezia. Se was present in all tissues (adductor, blood, foot, gills, intestine and mantle) and not immobilised or stored in a specific tissue, indicating that it plays a structural role in the tissues of A. trapezia. Se burden increased relative to size (shell length and dry mass) suggesting that Se is metabolically controlled within the organism. Se concentrations were found to fluctuate temporally because of: food availability in response to water temperatures; the reproductive cycle; and associated metabolic activities responding to temperature changes and food availability. Subcellular selenium associations in A. trapezia were examined to assist in the understanding of the fate of Se in marine tissues. Most of the Se was associated with proteins, suggesting that Se has a metabolic role in this marine organism. Proteins are intrinsically associated with the lipid bilayer of the cell membranes. A number of proteins (94, 85, 43, 36.5, 30, 23.4, 17.4 and 15 kDa) were separated by SDS PAGE from ethanol fractions. Determination of the Se concentration within individual proteins was not possible because the ratio of Se to protein was too low for further analysis. These findings indicated that Se plays a metabolic role in the tissues of the marine organism A. trapezia. The biochemical regulatory mechanism responsible for maintaining Se concentrations within the tissues is currently unknown.

Lake Macquarie is the largest estuarine lake in New South Wales and is located on the eastern seaboard of Australia, approximately 85 km north of Sydney.The study of heavy metal concentrations in surficial sediments, sediment cores, seagrasses and fish conducted by the New South Wales Department of Mines in 1974 revealed that significant heavy metal contamination of Lake Macquarie has occurred. The metalloid selenium was found in elevated concentrations in 1987. Selenium has a complex chemistry and is both an important nutrient and in high concentrations toxic. This review describes briefly the Lake Macquarie environment and suggests some approaches of modelling the remobilisation and cycling of selenium in sediment. The biogeochemical cycling of selenium in an estuarine environment is exceedingly complex. Factors include Eh, pH, ligand complexing ability, solubility of selenium containing minerals, sediment/soil characteristics, microbially-mediated reactions and physical reworking by biota (bioturbation). The goal of the model will be to be able to estimate the transport rates from a calculated value of Se concentration in sediment pore water resulting in a Se flux value for the interface between sediment and overlaying water.
www.ima.kth.se

Three approaches were employed to examine the effects of elevated sediment trace metal concentrations on estuarine/marine macrobenthic invertebrate assemblages. The initial study examined macroinvertebrate communities along a known polymetallic gradient, Lake Macquarie, NSW (gradient study). The second study experimentally tested if sediments sourced from different locations within Lake Macquarie differentially influenced the recolonisation of benthic invertebrates. The third study investigated the different recolonisation patterns of benthic invertebrates into sediments spiked with increasing concentrations of sediment-bound cadmium. In the Lake Macquarie gradient study, four locations (Cockle Bay, Warner's Bay, Kooroora Bay and Nord's Wharf) were sampled in winter 2000 and summer 2003 using a hierarchical design (location > site > plot). On both sampling occasions, the sediments showed strong gradients in lead, cadmium and zinc concentrations emanating from the Cockle Bay industrialised region in the lake's north, with concentrations being significantly lower in the most southern and less urbanised location (Nord's Wharf). In general, concentrations of lead, cadmium and zinc in the sediments increased among locations in the following order: Nord's Wharf > Kooroora Bay > Warner's Bay > Cockle Bay. AVSJSEM analyses indicated that in some sites in Cockle Bay, and to a lesser extent Warner's Bay, SEM concentrations exceeded their molar equivalence of AVS, indicating the potential for trace metals to be labile within the porewaters. Granulometry also changed along the gradient, with a higher proportion of silt/clay occurring in the locations with high metal concentrations. Conversely, the percentage of total organic carbon was higher in the less contaminated locations. In winter 2000, changes in benthic communities along the gradient supported the a priori hypotheses, with diversity and richness being greater in locations with lower concentrations of metals. Polychaetes were most numerous in Cockle Bay and Warner's Bay, whilst bivalves and gastropods were more abundant in Nord's Wharf and Kooroora Bay. Crustaceans were more numerous in Nord's Wharf; with all other locations having similar, lower, abundances. Ordination maps of the assemblages provided relatively clear separation of the assemblages among locations, with nonparametric multivariate analysis of variance (NPMANOVA) and subsequent pair-wise comparisons finding significant differences among the assemblages from all locations. SIMPER analyses found the highest level of dissimilarity was between the Nord's Wharf and Cockle Bay assemblages - primarily attributable to differences in the relative contributions of isopods; tellenid bivalves; and the polychaete families Spionidae, Opheliidae and Nephytidae. Weighted Spearman rank correlations (BIOENV) identified cadmium (Pw =0.74) as the strongest environmental (single or combination) variable to correlate with biotic assemblages. Benthic patterns along the gradient were less defined in summer 2003 due to a dramatic reduction in the abundance and diversity of fauna in Nord's Wharf. This decline was possibly attributable to a sustained reduction in salinity caused by a prolonged rainfall event. With the exception of Nord's Wharf, trends in the community indices and abundances of key taxa among the other locations were similar to those reported in winter 2000. Multivariate analyses discriminated the benthic assemblages from the four locations, with the findings from the NPMANOVA pair-wise comparisons indicating that the assemblages from all four locations were significantly different. SIMPER analyses showed the highest level of dissimilarity was between Nord's Wharf and Warner's Bay, with these differences being primarily attributable to their relative abundances of amphipods and polychaetes from the families Spionidae, Cirratulidae, Opheliidae and Capitellidae. BIOENV found that the combination of the sedimentary concentrations of cadmium and iron provided the best correlation (Pw =0.73) with biotic patterns, with similar correlations occumng with the addition of lead and its covariate, zinc (Pw =0.72). The combined findings from the gradient study established a strong correlation between trace metal concentrations within the sediments and suite of univariate and multivariate measurements. The low abundance and diversity of fauna in Nord's Wharf in the summer of 2003 highlighted the dynamic changes which can occur in the distributions of macrobenthic invertebrates. Although the study indicated that there was a strong relationship between trace metal concentrations and benthic community structure, the study was correlative, and requires subsequent experimental testing to confirm the causality of the observed relationships. The second component of the research was a translocation experiment using benthic recolonisation as an end-point. The experiment was performed to identify if the sediments, and not location, were influencing the composition of benthic assemblages in Lake Macquarie. Sediments were collected from three locations (Cockle Bay, Warner's Bay and Nord's Wharf), defaunated, and transplanted in three new locations along the south-east edge of the lake. At each location, 10 containers of each treatment were randomly placed in the sediment and allowed to recolonise for 22 weeks. Upon retrieval, the benthic communities were sampled and enumerated in conjunction with a variety of chemical and sedimentary measurements. Ten replicate invertebrate samples were also collected in the sediments adjacent to the experiment (ambient samples) at the completion of the experiment. Due to human interference, the containers from only two locations were analysed. Upon retrieval, pH and redox profiles of the sediments were similar to those expected in natural sediments. In general, concentrations of metals were low in the porewaters; however, iron precipitation on the porewater collection devices may have artificially increased the diffusion of metals, increasing concentrations near the sediment-water interface. Concentrations of SEM exceeded their AVS equivalence in some samples taken from the Cockle Bay and Warner's Bay treatments. Two-way ANOVAs found significant interactions between location and sediment treatments in diversity, evenness and the number of polychaetes, as well as significant differences in the number of capitellids and crustaceans among locations. Post-hoc comparisons of means found the Nord's Wharf sediment contained a higher mean number of individuals than the other treatments, including the ambient samples. nMDS ordination plots for both locations provided poor graphical discrimination of the assemblages among treatments; however, NPMANOVA detected significant location and treatment interactions. In both locations, pair-wise comparisons indicated that the assemblages within the Nord's Wharf treatments were significantly different to the Cockle Bay, Warner's Bay and ambient assemblages. No significant differences were detected between the Cockle Bay and Warner's Bay assemblages at either location. SIMPER analyses found the highest level of dissimilarity occurred between the ambient assemblages in Location 2 and the Nord's Wharf treatment, primarily due to the relative difference in the abundances of Capitellidae, Spionidae, Oweniidae, Nereididae and isopods among the assemblages. The findings from the translocation experiment suggest that the sediments are influencing the recolonisation of benthos. However, because differences were not detected between the Cockle Bay and Warner's Bay treatments, the approach used in the study shows potential as an in situ technique which could be used to assess the potential ecological risks of sediments fiom specific locations. Excluding cost and time considerations, the technique's primary disadvantage is the lack of a true control. As a result, the technique can only identify if the sediments are modifying benthic recolonisation, and not causality. The final component of the research experimentally tested if elevated concentrations of sediment-bound cadmium affected benthic invertebrate recolonisation. Sediments from the south coast of New South Wales (Durras Lake) were defaunated, and spiked with cadmium under anaerobic conditions to obtain three targeted cadmium concentrations: control (