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An estuary is a semi-enclosed or periodically closed coastal body of water in which the aquatic environment is affected by both freshwater and marine systems. There are five general types of estuaries recognised in Tasmania:
A recent study of Tasmanian estuaries recognised approximately 111 medium to large estuaries on the Tasmanian mainland and Bass Strait islands (Edgar et al 1999).
Estuaries are important because they act as a filter and a channelling conduit between land and sea, and are thus sensitive to change. The sheltered tidal waters also support unique communities of plants and animals and provide many species of fish with sheltered waters for spawning and a safe habitat for juveniles to develop.
Each estuary possesses a unique environment due to its shape, size, depth, degree of tidal variation and catchment characteristics such as rainfall and run-off and vegetation cover. Human activities such as agriculture, forestry and urban development can all affect water quality within the estuary.
Nine potential threats to Tasmanian estuaries have been identified:
(Source: Edgar et al 1999, Tasmanian Aquaculture and Fisheries Institute and Department of Primary Industries, Water and Environment.)
Further information on water quality in Tasmania can be found on the Department of Primary Industries, Water and Environment web site at http://www.dpiwe.tas.gov.au/inter.nsf/ThemeNodes/DREN-4VH8C4?open