Oceans | Coastal Processes | Intertidal Zone
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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.
The most recent field study of the Little Swanport estuary, Tasmania carried out by Crawford et al. (2006) collected monthly samples at sites throughout the estuary between January 2004 and January 2005. Measurements included water column nutrients, chlorophyll-a, dissolved oxygen, salinity, phytoplankton, zooplankton and oyster growth. This work demonstrated that freshwater flows had a significant effect on salinity, turbidity, dissolved oxygen and nutrient levels in the estuary. However, monthly sampling didn’t provide the temporal resolution necessary to detect potential flow-on effects on the biology (e.g. phytoplankton and zooplankton dynamics, oyster growth). To gain an improved understanding of the temporal dynamics of the estuary, including the response to freshwater flow, samples were collected weekly (chlorophyll-a), fortnightly (nutrients and zooplankton) and bimonthly (oysters) between March 2006 and June 2008 at a site in the lower estuary where the majority of oysters are farmed