State of estuary report for Georges Bay

Abstract

Indicators of estuarine ecosystem health – temperature, salinity, turbidity, dissolved oxygen, chlorophylla, 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. The results from these surveys are provided below and are compared with the data from 2004-05. Overall the bay appears to be in reasonable condition and is not showing any clear signs of degradation. However, the increased nitrate plus nitrite levels in the bay, the low summertime dissolved oxygen level in bottom waters near Medusa Cove and the increased numbers of introduced pest species in the macroinvertebrate fauna are cause for concern. The high nitrate levels and absence of macroinvertebrate fauna at the bridge near the mouth of the estuary suggest an impacted system.