Water use across a catchment and effects on estuarine health and productivity: Little Swanport

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