South Australia, and in particular the Spencer Gulf region, has significant opportunities for exp... more South Australia, and in particular the Spencer Gulf region, has significant opportunities for expansion of mining, with a large number of new mineral/mineral processing ventures possible. Associated with such development will be increased shipping and associated infrastructure (port development, desalination plants, power plants) along with biosecurity risks. Spencer Gulf is also recognised for its clean, green image in terms of its seafood production and has several tourism ventures based on environmental assets. Both wildcatch (e.g. prawns, snapper, garfish, King George whiting, abalone, southern rock lobster) and aquaculture (southern bluefin tuna, yellowtail kingfish, abalone, oysters, mussels) in Spencer Gulf provide important economic returns to the State and are expanding. Spencer Gulf is also the focus of several marine parks and zoning of sanctuary areas is underway. These are likely to conflict with both existing and proposed policy commitments associated with transport, aquaculture and fishing. The region has important relict populations of tropical species (e.g. commercially fished blue crab), and is the only area in the world known to support a breeding aggregation of cuttlefish. It is an important nursery area for fish. The key question to answer is how South Australia can support development of mining ventures, expansion of fishing and aquaculture, and conservation and recreation needs, while simultaneously delivering on the environmental, social and economic objectives associated with Spencer Gulf. The ultimate aim of an integrated research project around Spencer Gulf is to provide all stakeholders with access to independent and credible information about Spencer Gulf and opportunities to better understand any potential impacts so that informed decisions can be made. This will be achieved by creating an independent and credible decision support system to enable evidence-based assessment of development options with full consideration of social and economic benefits and cumulative environmental implications in a rapidly developing region.
High quality seabed data are fundamental to a wide range of engineering, management and science r... more High quality seabed data are fundamental to a wide range of engineering, management and science research applications stretching from shallow-water coastal environments, across the shelf and out on to the abyssal sea floor. Coastal applications require high-resolution, quality bathymetry data to support models for understanding currents and waves, sediment transport and erosion, hazard and risk assessment as well as ensuring safe navigation and informing development associated with infrastructure and commercial projects. Combined with other seabed data types, the information supports research around changing climate and marine biodiversity and provides development opportunities associated with energy and food production in support of the Blue Economy.
South Australia, and in particular the Spencer Gulf region, has significant opportunities for exp... more South Australia, and in particular the Spencer Gulf region, has significant opportunities for expansion of mining, with a large number of new mineral/mineral processing ventures possible. Associated with such development will be increased shipping and associated infrastructure (port development, desalination plants, power plants) along with biosecurity risks. Spencer Gulf is also recognised for its clean, green image in terms of its seafood production and has several tourism ventures based on environmental assets. Both wildcatch (e.g. prawns, snapper, garfish, King George whiting, abalone, southern rock lobster) and aquaculture (southern bluefin tuna, yellowtail kingfish, abalone, oysters, mussels) in Spencer Gulf provide important economic returns to the State and are expanding. Spencer Gulf is also the focus of several marine parks and zoning of sanctuary areas is underway. These are likely to conflict with both existing and proposed policy commitments associated with transport, aquaculture and fishing. The region has important relict populations of tropical species (e.g. commercially fished blue crab), and is the only area in the world known to support a breeding aggregation of cuttlefish. It is an important nursery area for fish. The key question to answer is how South Australia can support development of mining ventures, expansion of fishing and aquaculture, and conservation and recreation needs, while simultaneously delivering on the environmental, social and economic objectives associated with Spencer Gulf. The ultimate aim of an integrated research project around Spencer Gulf is to provide all stakeholders with access to independent and credible information about Spencer Gulf and opportunities to better understand any potential impacts so that informed decisions can be made. This will be achieved by creating an independent and credible decision support system to enable evidence-based assessment of development options with full consideration of social and economic benefits and cumulative environmental implications in a rapidly developing region.
Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotroph... more Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10–64 nmol L−1 d−1) can occur within the large inverse estuary Spencer Gulf, while c...
Abstract In the Australian spanner crab (Ranina ranina) fishery, management and industry are look... more Abstract In the Australian spanner crab (Ranina ranina) fishery, management and industry are looking for improvements to the existing indicators of stock abundance. Prior research linked several oceanographic indices to the catchability of spanner crabs; however, it was unclear whether nearshore (e.g. river-runoff) or region-specific oceanographic features (e.g. eddies and the East Australian Current) are responsible for these effects on catch rates. Using satellite remote sensing and fishery-independent survey data, we analysed the influence of oceanographic and environmental indices on spanner crab catch rates in southern Queensland. Outputs from Generalised Additive Models (GAM) show that catch rates exhibit a large amount of variability between different regions of the fishery, with highest catch rates at fishing grounds within 40 km from the shelf break. Offshore oceanic waters, transported into various regions by different oceanographic processes, were linked to an increase in catch rates. Lower concentrations of surface chlorophyll a were also correlated with higher catch rates, but only in survey regions exposed to the effects of the Fraser Gyre and at the mouth of bays. Overall, results highlighted that the effects of environmental indices on catch rates were not homogeneous across the fishery. Rather, relationships were linked to region-specific (
Deep Sea Research Part II: Topical Studies in Oceanography
Abstract We used a suite of physical, chemical and biological datasets to assess the influence of... more Abstract We used a suite of physical, chemical and biological datasets to assess the influence of upwelling/downwelling on enrichment and primary productivity in shelf waters of the eastern Great Australian Bight at seasonal and event scales. Results showed that the length of an upwelling season did not dictate its intensity or productivity, and that long seasons were not necessarily the most intense or productive. At the event scale, temperature and salinity were found to be better indicators of enrichment of shelf waters than wind stress, with temperatures 2 µm) and bursts of primary productivity (up to ∼ 700 mg C m−2 d−1). A key finding of this study was the importance of differentiating between upwelling events and enrichment events. The former occurred in the early upwelling season (November-December) and were demonstrated by periods of positive wind stress. The latter only occurred in the late upwelling season (January – April), and saw water with temperatures
Data from stock assessment surveys, published research and climate sensors were linked to model t... more Data from stock assessment surveys, published research and climate sensors were linked to model the interaction between fishing, physical‐oceanographic processes and spatial patterns of larval settlement for western king prawn [Penaeus (Melicertus) latisulcatus]. This information was used to evaluate the trade‐off between larval recruitment and catch during fishing periods that demand high prices but coincide with spawning. Total rates of larval settlement were maximized when tidal currents and atmospheric physical‐forcing components were coupled with simulations of larval swimming behaviour under average gulf temperatures. Average gulf temperatures sustained longer larval durations and increased larval settlement rates by over 12% compared with warmer gulf conditions simulated under a scenario of global warming. Reproductive data coupled with outputs from the biophysical model identified consistent inter‐annual patterns in the areas contributing to larval settlement success. Areas located in the north‐east, and central‐west of the fishery, consistently contributed to over 40% of all larvae reaching a settlement in each year. Harvest sensitivity analyses indicated that changes in the spatial patterns of pre‐Christmas fishing could lead to improvements in overall rates of the larval settlement while maintaining or improving the levels of catch. Future studies to refine the model inputs relating to physical processes, larval behaviour and mortality rates for P. latisulcatus coupled with surveys of juvenile prawn abundance to ground truth the modelled predictions, would allow stock recruitment relationships to be more closely examined and inform adaptive management of the fishery in the future.
Marine aggregates formed through particle coagulation, large ones (>0.05 cm) also called marin... more Marine aggregates formed through particle coagulation, large ones (>0.05 cm) also called marine snow, make a significant contribution to the global carbon flux by sinking from the euphotic zone, impacting the Earth’s climate. Since aggregate sinking velocity and carbon content are size-dependent, understanding the physical mechanisms controlling aggregate size distribution is fundamental to determining the biological carbon pump efficiency. Theoretical, laboratory and in-situ studies of flocculation have suggested that turbulence in the benthic boundary layer is important for aggregate formation and destruction, but the small number of field observations has limited our understanding of the role of turbulence on aggregation processes in the ocean surface layer away from energetic boundaries. Using simultaneous field observations of turbulence and aggregates, we show how aggregate formation, destruction, morphology and size distribution in the ocean surface layer (10–100 m) are me...
South Australia, and in particular the Spencer Gulf region, has significant opportunities for exp... more South Australia, and in particular the Spencer Gulf region, has significant opportunities for expansion of mining, with a large number of new mineral/mineral processing ventures possible. Associated with such development will be increased shipping and associated infrastructure (port development, desalination plants, power plants) along with biosecurity risks. Spencer Gulf is also recognised for its clean, green image in terms of its seafood production and has several tourism ventures based on environmental assets. Both wildcatch (e.g. prawns, snapper, garfish, King George whiting, abalone, southern rock lobster) and aquaculture (southern bluefin tuna, yellowtail kingfish, abalone, oysters, mussels) in Spencer Gulf provide important economic returns to the State and are expanding. Spencer Gulf is also the focus of several marine parks and zoning of sanctuary areas is underway. These are likely to conflict with both existing and proposed policy commitments associated with transport, aquaculture and fishing. The region has important relict populations of tropical species (e.g. commercially fished blue crab), and is the only area in the world known to support a breeding aggregation of cuttlefish. It is an important nursery area for fish. The key question to answer is how South Australia can support development of mining ventures, expansion of fishing and aquaculture, and conservation and recreation needs, while simultaneously delivering on the environmental, social and economic objectives associated with Spencer Gulf. The ultimate aim of an integrated research project around Spencer Gulf is to provide all stakeholders with access to independent and credible information about Spencer Gulf and opportunities to better understand any potential impacts so that informed decisions can be made. This will be achieved by creating an independent and credible decision support system to enable evidence-based assessment of development options with full consideration of social and economic benefits and cumulative environmental implications in a rapidly developing region.
High quality seabed data are fundamental to a wide range of engineering, management and science r... more High quality seabed data are fundamental to a wide range of engineering, management and science research applications stretching from shallow-water coastal environments, across the shelf and out on to the abyssal sea floor. Coastal applications require high-resolution, quality bathymetry data to support models for understanding currents and waves, sediment transport and erosion, hazard and risk assessment as well as ensuring safe navigation and informing development associated with infrastructure and commercial projects. Combined with other seabed data types, the information supports research around changing climate and marine biodiversity and provides development opportunities associated with energy and food production in support of the Blue Economy.
South Australia, and in particular the Spencer Gulf region, has significant opportunities for exp... more South Australia, and in particular the Spencer Gulf region, has significant opportunities for expansion of mining, with a large number of new mineral/mineral processing ventures possible. Associated with such development will be increased shipping and associated infrastructure (port development, desalination plants, power plants) along with biosecurity risks. Spencer Gulf is also recognised for its clean, green image in terms of its seafood production and has several tourism ventures based on environmental assets. Both wildcatch (e.g. prawns, snapper, garfish, King George whiting, abalone, southern rock lobster) and aquaculture (southern bluefin tuna, yellowtail kingfish, abalone, oysters, mussels) in Spencer Gulf provide important economic returns to the State and are expanding. Spencer Gulf is also the focus of several marine parks and zoning of sanctuary areas is underway. These are likely to conflict with both existing and proposed policy commitments associated with transport, aquaculture and fishing. The region has important relict populations of tropical species (e.g. commercially fished blue crab), and is the only area in the world known to support a breeding aggregation of cuttlefish. It is an important nursery area for fish. The key question to answer is how South Australia can support development of mining ventures, expansion of fishing and aquaculture, and conservation and recreation needs, while simultaneously delivering on the environmental, social and economic objectives associated with Spencer Gulf. The ultimate aim of an integrated research project around Spencer Gulf is to provide all stakeholders with access to independent and credible information about Spencer Gulf and opportunities to better understand any potential impacts so that informed decisions can be made. This will be achieved by creating an independent and credible decision support system to enable evidence-based assessment of development options with full consideration of social and economic benefits and cumulative environmental implications in a rapidly developing region.
Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotroph... more Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10–64 nmol L−1 d−1) can occur within the large inverse estuary Spencer Gulf, while c...
Abstract In the Australian spanner crab (Ranina ranina) fishery, management and industry are look... more Abstract In the Australian spanner crab (Ranina ranina) fishery, management and industry are looking for improvements to the existing indicators of stock abundance. Prior research linked several oceanographic indices to the catchability of spanner crabs; however, it was unclear whether nearshore (e.g. river-runoff) or region-specific oceanographic features (e.g. eddies and the East Australian Current) are responsible for these effects on catch rates. Using satellite remote sensing and fishery-independent survey data, we analysed the influence of oceanographic and environmental indices on spanner crab catch rates in southern Queensland. Outputs from Generalised Additive Models (GAM) show that catch rates exhibit a large amount of variability between different regions of the fishery, with highest catch rates at fishing grounds within 40 km from the shelf break. Offshore oceanic waters, transported into various regions by different oceanographic processes, were linked to an increase in catch rates. Lower concentrations of surface chlorophyll a were also correlated with higher catch rates, but only in survey regions exposed to the effects of the Fraser Gyre and at the mouth of bays. Overall, results highlighted that the effects of environmental indices on catch rates were not homogeneous across the fishery. Rather, relationships were linked to region-specific (
Deep Sea Research Part II: Topical Studies in Oceanography
Abstract We used a suite of physical, chemical and biological datasets to assess the influence of... more Abstract We used a suite of physical, chemical and biological datasets to assess the influence of upwelling/downwelling on enrichment and primary productivity in shelf waters of the eastern Great Australian Bight at seasonal and event scales. Results showed that the length of an upwelling season did not dictate its intensity or productivity, and that long seasons were not necessarily the most intense or productive. At the event scale, temperature and salinity were found to be better indicators of enrichment of shelf waters than wind stress, with temperatures 2 µm) and bursts of primary productivity (up to ∼ 700 mg C m−2 d−1). A key finding of this study was the importance of differentiating between upwelling events and enrichment events. The former occurred in the early upwelling season (November-December) and were demonstrated by periods of positive wind stress. The latter only occurred in the late upwelling season (January – April), and saw water with temperatures
Data from stock assessment surveys, published research and climate sensors were linked to model t... more Data from stock assessment surveys, published research and climate sensors were linked to model the interaction between fishing, physical‐oceanographic processes and spatial patterns of larval settlement for western king prawn [Penaeus (Melicertus) latisulcatus]. This information was used to evaluate the trade‐off between larval recruitment and catch during fishing periods that demand high prices but coincide with spawning. Total rates of larval settlement were maximized when tidal currents and atmospheric physical‐forcing components were coupled with simulations of larval swimming behaviour under average gulf temperatures. Average gulf temperatures sustained longer larval durations and increased larval settlement rates by over 12% compared with warmer gulf conditions simulated under a scenario of global warming. Reproductive data coupled with outputs from the biophysical model identified consistent inter‐annual patterns in the areas contributing to larval settlement success. Areas located in the north‐east, and central‐west of the fishery, consistently contributed to over 40% of all larvae reaching a settlement in each year. Harvest sensitivity analyses indicated that changes in the spatial patterns of pre‐Christmas fishing could lead to improvements in overall rates of the larval settlement while maintaining or improving the levels of catch. Future studies to refine the model inputs relating to physical processes, larval behaviour and mortality rates for P. latisulcatus coupled with surveys of juvenile prawn abundance to ground truth the modelled predictions, would allow stock recruitment relationships to be more closely examined and inform adaptive management of the fishery in the future.
Marine aggregates formed through particle coagulation, large ones (>0.05 cm) also called marin... more Marine aggregates formed through particle coagulation, large ones (>0.05 cm) also called marine snow, make a significant contribution to the global carbon flux by sinking from the euphotic zone, impacting the Earth’s climate. Since aggregate sinking velocity and carbon content are size-dependent, understanding the physical mechanisms controlling aggregate size distribution is fundamental to determining the biological carbon pump efficiency. Theoretical, laboratory and in-situ studies of flocculation have suggested that turbulence in the benthic boundary layer is important for aggregate formation and destruction, but the small number of field observations has limited our understanding of the role of turbulence on aggregation processes in the ocean surface layer away from energetic boundaries. Using simultaneous field observations of turbulence and aggregates, we show how aggregate formation, destruction, morphology and size distribution in the ocean surface layer (10–100 m) are me...
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