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We implemented a monitoring program developed by Crawford and White (2006), which was designed to assess the current condition of six key estuaries in NW Tasmania: Port Sorell, the Leven, Inglis, Black, Montagu and Arthur River estuaries. This study considered a range of water quality and ecological indictors commonly used to monitor estuaries. These included: salinity, temperature, dissolved oxygen, turbidity, pH, nutrients (nitrate + nitrite, dissolved reactive phosphorus and ammonia), silica molybdate reactive and chlorophyll a for the water column; chlorophyll a and macroinvertebrate community structure amongst the sediments. The data represented by this record was collected in Montagu River.
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Seabed areas were derived by aggregating and dissolving the boundaries of the 1 degree S57 file series for the Australian continental shelf and Lord Howe Island shelf (200 m). These areas were defined by the Australian Hydrographic Service (AHS).
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Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a ‘top-down’ driver of ecosystems) was manipulated over 12 months to estimate (1) the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2) the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia. In parallel, the role of one of the ‘bottom-up’ drivers of ecosystem structure was examined by (3) manipulating local nutrient levels and thus attempting to alter primary production on the experimental reefs. It was found that densities of 8 or more urchins m-2 (≥ 427 g m-2 biomass) lead to complete overgrazing of kelp beds while kelp bed recovery occurred when densities were reduced to ≤ 4 urchins m-2 (≤ 213 g m-2 biomass). This experiment provided further insight into the dynamics of transition between urchin barrens and kelp beds by exploring possible tipping-points which in this system can be found between 4 and 8 urchins m-2 (213 and 427 g m-2 respectively). Local enhancement of nutrient loading did not change the urchin density required for overgrazing or kelp bed recovery, as algal growth was not affected by nutrient enhancement.
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Kelps are in global decline due to climate change, including ocean warming. To identify vulnerable species, we need to identify their tolerances to increasing temperatures and whether tolerances are altered by co-occurring drivers such as inorganic nutrient levels. This is particularly important for those with restricted distributions, which may already be experiencing thermal stress. To identify thermal tolerance of the range restricted kelp Lessonia corrugata, we conducted a laboratory experiment on juvenile sporophytes to measure performance (growth, photosynthesis) across its thermal range (4 – 22 °C). We found the upper thermal limit for growth and photosynthesis to be ~ 22 – 23 °C, with an optimum of ~ 16 °C. To determine if elevated inorganic nitrogen availability could enhance thermal tolerance, we compared performance of juveniles under low (4.5 µmol/day) and high (90 µmol/day) nitrate conditions at and above the thermal optimum (16 – 23.5 °C). Nitrate enrichment did not enhance thermal performance at temperatures above the optimum but did lead to elevated growth rates at the thermal optimum 16 °C. Our findings indicate L. corrugata is likely to be extremely susceptible to moderate ocean warming and marine heatwaves. Peak sea surface temperatures during summer in eastern and northeastern Tasmania can reach up to 20 – 21 °C and climate projections suggest that L. corrugata’s thermal limit will be regularly exceeded by 2050 as south-eastern Australia is a global ocean-warming hotspot. By identifying the upper thermal limit of L. corrugata we have taken a critical step in predicting the future of the species in a warming climate.
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A total of 111 estuaries of moderate or large size were recognised around Tasmania and associated Bass Strait islands. The catchments of these estuaries were mapped using GIS, and available data on geomorphology, geology, hydrology and rainfall collated for each estuary and catchment area. Tasmanian estuaries were classified into nine groups on the basis of physical attributes that included salinity and tidal data collected during a field sampling program. Baseline information on the abundance, biomass and estimated production of macrobenthic invertebrate species was collected during a quantitative sampling program at 55 sites in 48 Tasmanian estuaries. These data were generally obtained at three different intertidal levels and two shallow subtidal depths at each site, and included information on a total of 390 taxa and over 100,000 individuals. Data on the distribution of 101 fish species, as obtained during surveys of 75 Tasmanian estuaries using seine nets by Last (1983) with some supplementary sampling, were also incorporated into the study.
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Spatially referenced underwater video transect data for Tasmanian coastal waters from the LWM (Low water mark) to 80 metres in depth or 1.5 kms from shore.
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Database includes data on abalone size at maturity, collected from sites around Tasmania from 1988.
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This dataset is a compilation of published records of 230Thorium - normalised lithogenic and biogenic fluxes from the Southern Ocean, south of 30S. All age models and derived fluxes were taken as published. Lithogenic fluxes are based on 232Th concentrations. Opal and carbonate fluxes are also included where available. In some cases fluxes had to be derived from published data. LGM values for each core represent an average of observations between 28 - 18 ka BP and Holocene values represent an average of observations from 10 - 0 ka BP. These data were collated as part of modelling study of the Southern Ocean during the LGM (Saini et al, Southern Ocean ecosystem response to Last Glacial Maximum boundary conditions, Submitted to Paleoceanography and Paleoclimatology, 2021)
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This study assessed the spatial and temporal (horizontal and vertical) distribution of Asterias amurensis larvae in the Derwent Estuary and adjacent Storm Bay, SE Tasmania. Horizontal transport and development was assessed by collecting plankton samples at 2 or 4 week intervals, from July to December 2001, at 4 sites in the Derwent Estuary and 6 sites in Storm Bay. The effects of light and salinity on vertical distribution of larvae was examined over a 24 hour tidal and diel cycle.
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This project undertook a rapid exploration of information on a priority subset of species identified by the Department of Climate Change, Energy, the Environment and Water (DCCEEW) and the National Offshore Petroleum Safety and Environment Authority (NOPSEMA) that are listed as critically endangered or endangered under the Environment Protection and Biodiversity Conservation Act 1999. It specifically focused on these species in relation to the Gippsland declaration area, and the adjacent areas to the declaration area in Bass Strait. This rapid exploration of information was conducted as follows: 1) identify datasets and information sources relevant to priority species identified by DCCEEW and NOPSEMA for the Gippsland declaration area; 2) identify the source of these datasets and information and their level of accessibility; 3) evaluate the utility of datasets and information identified in 2) for assessments/regulatory processes required to be undertaken by DCCEEW and NOPSEMA; and 4) identify what activities would need to be undertaken to improve the accessibility and utility of datasets and information sources identified in 3) that are not currently accessible in useable formats. Fifteen priorities species (12 birds, 3 cetaceans) were identified for which publicly-available occurrence data could be located. This record and the attached download describes the data inventory for North-Eastern Siberian Red Knot (Calidris canutus). To download the data inventory for all fifteen priority species, see https://doi.org/10.25959/GB51-RW44.