Healthcare reforms and restructuring have been a global phenomenon since the early 1980s. The major structural reforms in the healthcare system in New South Wales (NSW) including the introduction and implementation of the area health management model (1986), the senior executive service (1989) and performance agreements (1990), heralded a new era in management responsibility and accountability. It is believed that the reforms, the process of the reforms, and the instability brought about by the reforms may have not only resulted in the change of senior healthcare management practices, but also in the change of competencies required for senior healthcare managers in meeting the challenges in the new era. However, limited studies have been conducted which examined how health reforms affected its senior health executive workforce and the above changes. Moreover, no study on senior healthcare managers has focused specifically on NSW after the major reforms were implemented. The purpose of this research was to examine how reforms in the NSW Health public sector affected its senior health executive workforce between 1990 and 1999 in terms of their roles and responsibilities, the competencies required, and the challenges they faced. This study, from a broad perspective, aimed to provide an overview of the NSW reforms, the forces behind the reforms and the effects the reforms may have had on senior health managers as predicted by the national and international literature. This study also explored the changes to the senior health executive workforce in the public sector during the period of rapid change in the 1990s and has provided indications of the managerial educational needs for future senior healthcare managers. Both quantitative and qualitative data have been collected by this study using triangulated methods including scientific document review and analyses, a postal questionnaire survey, and in-depth telephone interviews. The findings from the two quantitative methods informed and guided the development of the open-ended questions and overall focus of the telephone interviews. This study found differences in the characteristics and employment-related aspects between this study and previous studies in the 1980s and 1990s, and identified four major tasks, twelve key roles and seven core competencies required by senior health executives in the NSW Health public sector between 1990 and 1999. The study concludes that the demographic characteristics and the roles and responsibilities of the NSW Health senior executive workforce since the reforms of the 1980s have changed. This study also identified seven major obstacles and difficulties experienced by senior health executives and suggested that during the introduction and implementation of major healthcare reforms in NSW since 1986, barriers created by the ‘system’ prevented the achievement of its full potential benefits. Although this study did not focus on detailed strategies on how to minimise the negative impact of the health reforms on the senior health executives or maximise the chance of success in introducing new changes to the system, some suggestions are proposed. Most significantly, the study has developed a clear analytical framework for understanding the pyramidal relationships between tasks, roles and competencies and has developed and piloted a new competency assessment approach for assessing the core competencies required by senior health managers. These significant findings indicate the need for a replication of the study on an Australia-wide scale in order to extend the generalisability of the results and test the reliability and validity of the new competency assessment approach at various management levels in a range of healthcare sectors. This is the first study acknowledging the impact of the introduction of the area health management model, the senior executive service and performance agreements in the NSW public health system through an original insight into the personal experiences of the senior health executives of the reforms and examination of the major tasks that senior health executives performed and relevant essential competencies required to perform these tasks. The possible solutions identified in this study can guide the development of strategies in providing better support to senior healthcare managers when large-scale organisational changes are proposed in the future.

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).

The following research project was a comparative study of teachers in Support Units and teachers in Special Schools. They were teachers currently involved with the implementation of the 1989 NSW Department of Education Mandatory Curriculum Change for the education of students with severe intellectual disability. The purpose of the research was to present a comparative study on teachers' responses, in both educational settings, examining their understanding of the curriculum change, the concerns of individuals and the levels of curriculum usage in relation to the factors affecting implementation. The application of the Concerns-Based Adoption Model of Change (Hall and Loucks, 1987), enabled the study to focus on the various forms of the innovation, including the innovation configuration, stages of concern, and the levels of use from the two given perspectives, teachers in Support Units and teachers in Special Schools, in relation to the major factors affecting implementation. The study findings highlighted that in both educational settings, change is accomplished by individuals and is a highly personal experience, demanding adequate support by facilitators of the change through appropriate actions, in order to assist effective and successful implementation of the change.

The experiments described in this thesis were designed to assess changes in pasture dynamics (biomass and species composition of pasture) of grazing land on the Southern Tablelands of ACT and NSW, after 16 combinations of rabbit control treatments had been applied. The rabbit control performed by CSIRO Division of Wildlife and Ecology consisted of all combinations of presence-absence of Poisoning (using sodium monofluoroacetate, 1080: POIS), Ripping (ripping warrens using a tractor fitted with ripping tynes: RIP), Fumigation (pressure fumigation using chloropicrin: FUM) and repeated follow-up fumigation (using phostoxin pellets one, six and eighteen months after completion of the initial treatment: ANN). The pasture was assessed before treatments were applied, and every six months after rabbit control treatments. Treatment combinations were assigned randomly in a 24 factorial design on a total of 32 sites. There was a significant increase of pasture biomass at the RIP+ANN treatment at post-treatment sample 5. The analysis of covariance did not detect any other significant increase or decrease of pasture biomass for any rabbit control treatment, at any posttreatment sample. A significant increase of grass species occurred for the treatments of POIS+RIP+FUM, POIS and RIP+ANN for the post-treatment samples of 1, 3 and 5 respectively. There was a significant increase of thistles at the rabbit control treatments of POIS+RIP+FUM+ANN (post-treatment sample 1), RIP, ANN, RIP+FUM, RIP+FUM+ANN and POIS+RIP+FUM+ANN (post-treatment sample 3) and RIP and FUM+ANN (post-treatment sample 5). A significant increase of weeds occurred at FUM (post-treatment sample 3) and at FUM+ANN (post-treatment sample 5). No significant changes in the amount of herbs or legumes was apparent for any rabbit control treatment or post-treatment sample. There were no significant decreases for any species group. Except for the significant results for post-treatment sample 1, all significant increases of biomass for any species group occurred during spring (post-treatment sample 3 and 5) which suggests a growth phase during spring then subsequent dieback (particularly for thistles and weeds), as any change was not detected in the following autumn sample. No strong trend is evident for any particular rabbit control treatments, or any combination of treatments. Analysis of covariance revealed that the rabbit control treatment of RIP+ANN showed significant increases in both total biomass of pasture and grass biomass during post-treatment sample 5. This treatment reduced the number of active entrances the most. Significant positive correlations were found between pasture biomass (total) with grass, herb, legume, thistle and weed species groups. Significant negative correlations between grass biomass and the number of active entrances were found when the rabbit control had been highly effective in reducing the number of active entrances. When rabbit control had not been very successful, there was a significant positive but low correlation with the number of active entrances. There was no significant relationship between the number of active entrances with the weight of rabbit dung pellets. It is reasoned that they are different measures of rabbit abundance. More rabbit dung pellets were found closer to the warren than further away from the warren, but there was no correlation between rabbit dung and pasture biomass. Rainfall was above average for most of the experiment, biomass increased accordingly, and rabbit control was highly successful. The resulting changes in the pasture were difficult to detect, although some increases in species composition groups occurred. It is reasoned that the changes observed are partly attributable to seasonal conditions, and to high rainfall. Grazing by domestic animals, sheep and cattle, had been found to be consistent throughout the experiment.

The cycling of arsenic in the marine photosynthetic plants and algae was examined by analysing total arsenic concentrations and arsenic species in selected marine photosynthetic organisms from the south-east coast, NSW, Australia. A range of elements required for metabolism in photosynthetic organisms were also analysed to determine if any relationship between these elements and arsenic concentrations occurred. Organisms were selected from salt marsh and mangrove ecosystems, marine inter-tidal and estuarine environments, and two species of marine phytoplankton cultured, to represent the different marine environments that primary producers inhabit. Organisms selected were compared to species within their own environment and then a comparison made between the varying ecosystems. In the salt marsh and mangrove ecosystems, the leaves of four species, the mangrove Avicennia marina, the samphire Sarcocornia quinqueflora, the seablight Suaeda australis, and the seagrass Posidonia australis were sampled from three locations from the south-east coast of NSW using nested sampling. Mean total arsenic concentrations (mean � sd) dry mass for all locations were A. marina (0.38 � 0.18 �g g-1 to 1.2 � 0.7 �g g-1), S. quinqueflora (0.13 � 0.06 �g g-1 to 0.46 � 0.22 �g g-1), S. australis (0.03 � 0.06 �g g-1 to 0.05 � 0.03 �g g-1)and P. australis (0.34 � 0.10 �g g-1 to 0.65 � 0.26 �g g-1). Arsenic concentrations were significantly different between species and locations but were consistently low compared to marine macroalgae species. Significant relationships between As and Fe concentrations for A. marina, S. quinqueflora and P. australis and negative relationship between As and Zn concentrations for S. quinqueflora could partially explain arsenic concentrations in these species. No relationship between As and P concentrations were found in this study. All terrestrial species contained predominantly inorganic arsenic in the water extractable and residue fractions with minor concentrations of DMA in the water-soluble fraction. P. australis also contained dimethylated glycerol and phosphate arsenoriboses. The presence of arsenobetaine, arsenocholine and trimethylated glycerol arsonioribose is most likely due to the presence of epiphytes on fronds on P. australis. In contrast, macroalgae contained higher total arsenic concentrations compared to marine terrestrial angiosperms. Total arsenic concentrations also varied between classes of algae: red macroalgae 4.3 �g g-1 to 24.7 �g g-1, green macroalgae 8.0 �g g-1 to 11.0 �g g-1 and blue green algae 10.4 �g g-1 and 18.4 �g g-1. No significant relations were found between As concentrations and concentrations of Fe, Co, Cu, Mn, Mo, Mg, P and Zn concentrations, elements that are required by macroalgae for photosynthesis and growth. Distinct differences between algal classes were found for the proportion of arsenic species present in the lipid and water-soluble fractions, with green algae having a higher proportion of As in lipids than red or estuarine algae. Acid hydrolysis of the lipid extract revealed DMA, glycerol arsenoribose and TMA based arsenolipids. Within water-soluble extracts, red and blue-green algae contained a greater proportion of arsenic as inorganic and simple methylated arsenic species compared to green algae, which contained predominantly glycerol arsenoribose. Arsenobetaine, arsenocholine and tetramethylarsonium was also present in water-soluble extracts but is not normally identified with macroalgae and is again likely due to the presence of attached epiphytes. Residue extracts contained predominantly inorganic arsenic, most likely associated with insoluble constituents of the cell. Mean arsenic concentrations in the green microalgae Dunaliella tertiolecta were 13.3 �g g-1 to 14.5 �g g-1, which is similar to arsenic concentrations found in green macroalgae in this study. Diatom Phaeodactylum tricornutum arsenic concentrations were 1.62 �g g-1 to 2.08 �g g-1. Varying the orthophosphate concentrations had little effect on arsenic uptake of microalgae. D. tertiolecta and P. tricornutum metabolised arsenic, forming simple methylated arsenic species and arsenic riboses. The ratio of phosphate to glycerol arsenoriboses was higher than that normally found in green macroalgae. The hydrolysed lipid fraction contained DMA arsenolipid (16-96%) with minor proportions of phosphate arsenoribose (4-23%). D. tertiolecta at f/10 phosphate concentration, however, contained glycerol arsenoribose and another arsenic lipid with similar retention as TMAO as well as DMA. The similarities between arsenic species in the water-soluble hydrolysed lipids and water-soluble extracts, especially for P. tricornutum, suggests that cells readily bind arsenic within lipids, either for membrane structure or storage, releasing arsenic species into the cytosol as degradation of lipids occurs. Inorganic arsenic was sequestered into insoluble components of the cell. Arsenic species present in D. tertiolecta at lower phosphate concentrations (f/10) were different to other phosphate concentrations (f/2, f/5), and require further investigation to determine whether this is a species-specific response as a result of phosphate deficiency. Although there are similarities in arsenic concentrations and arsenic species in marine photosynthetic organisms, it is evident that response to environmental concentrations of arsenic in uncontaminated environments is dependent on the mode of transfer from the environment, the influence of other elements in arsenic uptake and the ability of the organism to metabolise and sequester inorganic arsenic within the cell. It is not scientifically sound to generalise on arsenic metabolism in �marine plants� when species and the ecosystem in which they exist may influence the transformation of arsenic in higher marine organisms. There is no evidence to suggest that angiosperms produce AB as arsenic is mostly present as inorganic As, with little or no arsenic present in the lipids. However, marine macro- and microalgae both contain lipids with arsenic moieties that may be precursors for AB transformation. Specifically, the presence of TMA and dimethylated arsenoribose based arsenolipids both can transform to AB via intermediates previously identified in marine organisms. Further identification and characterization of As containing lipids is required.

Doctor of Philosophy (PhD) / After the turmoil of the 1890s shearing contractors eliminated some of the frustration from shearers recruitment. At the same time closer settlement concentrated more sheep in small flocks in farming regions, replacing the huge leasehold pastoral empires which were at the cutting edge of wool expansion in the nineteenth century. Meanwhile the AWU succeeded in getting an award for the pastoral industry under the new arbitration legislation in 1907. Cultural and administrative influences, therefore, eased some of the bitter enmity which had made the annual shearing so unstable. Not all was plain sailing. A pattern of militancy re-emerged during World War I. Shearing shed unrest persisted throughout the interwar period and during World War II. In the 1930s a rival union with communist connections, the PWIU, was a major disruptive influence. Militancy was a factor in a major shearing strike in 1956, when the boom conditions of the early-1950s were beginning to fade. The economic system did not have satisfactory mechanisms to cope. Unionised shearers continued to be locked in a psyche of confrontation as wool profits eroded further in the 1970s. This ultimately led to the wide comb dispute, which occurred as wider pressures changed an economic order which had not been seriously challenged since Federation, and which the AWU had been instrumental in shaping. Shearing was always identified with bushworker ‘mateship’, but its larrikinism and irreverence to authority also fostered individualism, and an aggressive ‘moneymaking’ competitive culture. Early in the century, when old blade shearers resented the aggressive pursuit of tallies by fast men engaged by shearing contractors, tensions boiled over. While militants in the 1930s steered money-makers into collectivist versions of mateship, in the farming regions the culture of self-improvement drew others towards the shearing competitions taking root around agricultural show days. Others formed their own contracting firms and had no interest in confrontation with graziers. Late in the century New Zealanders arrived with combs an inch wider than those that had been standard for 70 years. It was the catalyst for the assertion of meritocracy over democracy, which had ruled since Federation.

Doctor of Philosophy (PhD) / After the turmoil of the 1890s shearing contractors eliminated some of the frustration from shearers recruitment. At the same time closer settlement concentrated more sheep in small flocks in farming regions, replacing the huge leasehold pastoral empires which were at the cutting edge of wool expansion in the nineteenth century. Meanwhile the AWU succeeded in getting an award for the pastoral industry under the new arbitration legislation in 1907. Cultural and administrative influences, therefore, eased some of the bitter enmity which had made the annual shearing so unstable. Not all was plain sailing. A pattern of militancy re-emerged during World War I. Shearing shed unrest persisted throughout the interwar period and during World War II. In the 1930s a rival union with communist connections, the PWIU, was a major disruptive influence. Militancy was a factor in a major shearing strike in 1956, when the boom conditions of the early-1950s were beginning to fade. The economic system did not have satisfactory mechanisms to cope. Unionised shearers continued to be locked in a psyche of confrontation as wool profits eroded further in the 1970s. This ultimately led to the wide comb dispute, which occurred as wider pressures changed an economic order which had not been seriously challenged since Federation, and which the AWU had been instrumental in shaping. Shearing was always identified with bushworker ‘mateship’, but its larrikinism and irreverence to authority also fostered individualism, and an aggressive ‘moneymaking’ competitive culture. Early in the century, when old blade shearers resented the aggressive pursuit of tallies by fast men engaged by shearing contractors, tensions boiled over. While militants in the 1930s steered money-makers into collectivist versions of mateship, in the farming regions the culture of self-improvement drew others towards the shearing competitions taking root around agricultural show days. Others formed their own contracting firms and had no interest in confrontation with graziers. Late in the century New Zealanders arrived with combs an inch wider than those that had been standard for 70 years. It was the catalyst for the assertion of meritocracy over democracy, which had ruled since Federation.

The present study was undertaken to investigate the concerns of secondary school teacher-librarians, that the subject headings set down by the Australian Schools Catalogue Information Service (ASCIS) do not cover topics in senior sourses of study. NSW HSC Economics was chosen to test this perception. Terms were extracted from three textual sources (syllabus, textbook and examination papers) and checked against the subject headings in the ASCIS Subject Headings List. A comparison was made between terms which matched exactly, those which were only partially matched and those which had no match. The linguistic complexity of the term (single-word or multi-word) and the number of textual sources using the term were also taken into account. The results showed a varying degree of match between textual terms and subject headings. Single-word terms found in more than one textual source were much more likely to be found in the subject headings than those from only one textual source. Multi-word terms were found less frequently than single-word terms, but were also more likely to be found when they came from more than one textual source. There was a large number of partial matches in this group, and these were found to be more general in concept than the textual terms. Most of the terms were found, but the general nature of the partial matches and the lack of adequate cross references may cause problems in subject analysis and retrieval.

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 (<O.1 ug/g), Low-Cd (15 Cd ug/g) and High-Cd (150 Cd ug/g). The physio-chemical properties of the waters and porewater concentrations of cadmium were monitored over a 28-day equilibration period, with declines in pH mediated with the addition of NaOH(aq). At the end of the equilibration period, porewater concentrations of cadmium were low in the Low-Cd and High-Cd treatments (maximum <l.5 ug/L in High-Cd), and below the detection limit in the control. Cadmium was not detected in the control sediments, with concentrations in the Cd-Low and Cd-High sediments exceeding their targeted concentrations, with final mean concentrations of 17 ug/g and 183 ug/g, respectively. The experimental design was similar to that employed in the translocation experiment, with 10 containers from each treatment transplanted into the sediments at three locations within Lake Macquarie. After 20 weeks, the containers were collected, along with benthic invertebrate samples from the ambient sediments. Data was not used from Location C due to extensive sediment deposition on the transplanted treatments. Significant declines occurred in the concentrations of cadmium in both the Low-Cd and High-Cd sediments, with the greatest loss occumng in the surficial sediments. The loss of cadmium was probably due to the differential loss of the fine fraction through physical means (hydrodynamic) rather than fluxing, as it assumed that the cadmium was primarily sediment-bound and relatively insoluble under anoxic conditions. Mean porewater concentrations of cadmium were below the detection limit in the control treatments; < 1 ug/L in the Low-Cd treatment, and generally < 2ug/L in the High-Cd, with the exception of some samples in Location B (maximum 5.6 ug/L) Concentrations of ammonia were low in the porewaters from the surficial sediments, with concentrations being significantly higher, and potentially toxic, in the anoxic porewaters (7 cm depth). In comparison to the previous recolonisation experiment, the number of individuals which recolonised the cadmium-spiked treatments was low, and significantly lower than the mean number of individuals sampled in the ambient sediments. No significant differences were detected among the treatments or locations (and their interactions) in diversity (H'), richness (d) or evenness (J). The number of polychaetes and molluscs significantly differed among the treatments, with post-hoc analyses indicating these differences were not among the cadmium-spike treatments, but were due to a greater mean abundance of these taxa in the ambient sediments. A significant interaction between treatment and location was detected in the mean abundance of crustaceans, with the ambient sediments having significantly lower mean abundances in both Location A and B. Ordination plots of the experiments in Location A and B provided poor graphical discrimination among the spiked treatments, although the ambient assemblages appear to be separated from the cadmium-spiked assemblages. NPMANOVA detected a significant interaction between treatments and locations, as well as among treatments. In both Location A and B, pair-wise analyses found the assemblages in the ambient sediments to be significantly different to the assemblages in all three cadmium treatments, with no differences being detected among the latter. SIMPER analyses found the highest levels of dissimilarity occurred between the spike-treatments and the ambient sediments, with these differences being primarily due to the relatively higher abundance of decapods in the spiked treatments, and capitellids in the ambient sediments. The cadmium-spiking component of the experiment clearly illustrated that artificially increasing the trace metal concentrations of metals in estuarine sediments is a complex process which needs to be performed in a methodological manner in order to obtain homogenous treatments with low porewater concentrations, and minimal artefacts. Furthermore, the results confirmed that the equilibration time for sediments can be extensive (several weeks), even in the case of organically rich sediments. The timing of the experiment (commenced late summer, February, 2003) appears to the major factor for the relatively low recolonisation rates, with the experiment missing the main larval recolonisation period between spring and early summer. Even in the highest treatment, elevated concentrations of cadmium did not appear to affect benthic recolonisation. This finding is supported by other experimental studies which suggest that concentrations of a single isolated metal must considerably exceed current guideline values (or contain high porewater concentrations) in order to elicit a biological effect. Nevertheless, as trace metals generally co-occur with other contaminants - with the response of multiple contaminants being possibly additive or synergistic - a conservative guideline value may be suitable in the interim as a precautionary measure. The findings of this thesis suggest that elevated concentrations of trace metal mixtures in estuarine sediments can affect the structure and composition of benthic communities; however, identifying causality is difficult. Although there has been an increase in the use of manipulative field experiments as a means of reducing the confounding influence of covariables found in field studies, this approach also has limitations, e.g. spatial and temporal scale issues, container effects, cost and biogeochemical changes to the sediments. Measuring stress at a community level is a fundamental component of estuarine risk assessment programs; and in isolation this approach can produce subjective and confounded findings. In order to accurately assess the risks associated with trace metal contaminated sediments, an integrated approach (e.g. weight of evidence) is required, one which uses multiple lines of evidence sourced from various chemical, environmental biological measurements.

Thesis submitted for the degree of Doctor of Philosophy University of Western Sydney. / Title from electronic document (viewed 2/6/10) Interviews held with: "James' Dharug, Traditional Custodian; Dr. Rob Lesslie, conservation biologist, Dr. Val Plumwood, environmental philosopher, Virginia Young, Director WildCountry Project, Professor Mike Archer, Dr. Deborah Bird Rose, anthropologist, Ms. Penny Figgis, former Vice President of ACF, Dr. Tim Flannery, Director South Australian Museum, Mr. Dean Stewart, Aboriginal Education Officer, Melbourne Botanic Gardens, Dr. Rosemary Hill, ACF Northern Lands Project Officer, Professor Harry Recher.