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  • The aim of the project was to determine the particulate organic carbon concentration in coastal polynyas and off-shelf sites south of the Polar Front. Data is collected from the CTD deployed at various stations. This record descripbes three datafiles. (1) POC_data: station, pressure, temperature, conductivity, salinity, PAR, total beam attenuation coefficients (c), attenuation by particles (cp), site, particulate organic carbon concentration (from optical measurements), rho, longitude and latitude. (2) Ammonium: station, pressure, site, ammonium, latitude, longitude (3) POC_PON_ratio: site, depth, particulate organic carbon concentration (measured) particulate organic nitrogen concentration (measured), C:N ratio.

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    Water quality and biological data was collected from four tide-dominated river estuaries indicative of catchments with varying levels of human impacts to: 1) assess draft indicator levels for water quality, and 2) investigate biological indicators of estuarine health in NW Tasmania. This data includes sampling from Detention River, Duck Bay, Montagu River and Black River

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    This study considered a range of water-column and sediment (benthos) based variables commonly used to monitor estuaries,utilising estuaries on the North-West Coast of Tasmania (Duck, Montagu, Detention, and Black River). These included: salinity, dissolved oxygen, turbidity, nutrient and chlorophyll a levels for the water-column; and sediment redox, organic carbon content, chlorophyll a and macroinvertebrate community structure amongst the benthos. In addition to comparing reference with impacted estuaries, comparisons were also made across seasons, commensurate with seasonal changes in freshwater river input, and between regions within estuaries (upper and lower reaches) - previously identified in Hirst et al. (2005). This design enabled us to examine whether the detection of impacts (i.e. differences between reference and impacted systems) was contingent on the time and location of sampling or independent of these factors. This data includes sampling from Duck River, Montagu River, Detention River, and Black River.

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    Biologically relevant macronutrients, nitrate + nitrite, silicate, phosphate and ammonia, were measured at all sites throughout the study. Nitrate + nitrite values (NOx) at the surface showed clear seasonal trends, peaking over winter and drawing down to near zero in summer and autumn. Phosphate concentrations also reached a peak in winter, which was associated with Southern Ocean influence. Median ammonium concentrations at all sites were generally <0.5 μM, with no clear peaks in any season or month. Overall, the lowest values were measured in August and other months showed reasonable spread around the median. Median silicate concentrations were consistently highest at sites 1 and 9, followed by site 5. Water from the River Derwent flows through site 1, then tracks east towards site 9 then site 5. Seasonally, silicate was generally highest in winter when the River Derwent outflow is also greatest.

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    Indicators of estuarine ecosystem health – temperature, salinity, turbidity, dissolved oxygen, chlorophyll a, pH, nutrients - were sampled each month for twelve months at four sites in Georges Bay and at the bridge at the river mouth by the Tasmanian Aquaculture and Fisheries Institute (TAFI), community volunteers and Break O’Day Council staff. Another indicator, macroinvertebrate fauna, was sampled by TAFI in winter and summer, and data were obtained on pathogen levels from the Tasmanian Shellfish Quality Assurance Program.

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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.