Index of Estuary Condition

Estuaries are semi-enclosed waterbodies where freshwater from streams and rivers mixes with saltwater from the ocean. Estuaries have unique vegetation, provide important habitat for waterbirds and are nursery grounds for many fish species.

DELWP developed a condition assessment method for estuaries called the Index of Estuary Condition (IEC). The IEC was applied to estuaries throughout Victoria to document their current condition and establish a baseline for future assessments. This is assisting in guiding the management of Victoria’s estuaries.

The IEC focuses on five components of estuaries: physical form, hydrology, water quality, flora and fish. ARI was involved in the fish, flora and water quality themes:

• Fish - used as representative of the broader community of estuary animals, as fish respond to environmental, ecological, physical and hydrological factors and are an important estuary component that is of broad interest to communities.
• Flora - includes the structure of vegetation along shorelines and whether submerged vegetation is predominantly seagrass or macroalgae.
• Water quality - includes clarity, which influences the type and extent of submerged vegetation, and chlorophyll-a concentration, which is indicative of primary production that is responsive to nutrient inputs and is important for estuarine health. This component was assessed in partnership with catchment management authorities and citizen scientists, to draw on valuable local knowledge of our estuaries.