Abstract
Multimetric indices, incorporating information on a range of fish community attributes, have been shown to provide an effective, simple and sensitive method for evaluating the health or integrity of aquatic environments worldwide. We outline the development of a fish-based, multimetric index of estuarine health for the Swan Estuary, Western Australia, and focus on recent advances in metric selection.
An extensive suite of fish community characteristics (metrics), including species composition, diversity and abundance, and measures of trophic structure and life history function, were tested for their suitability for incorporation into an Estuarine Health Index (EHI). Meaningful reference conditions for each selected metric will be established for each region of the Swan Estuary, using historical fish assemblage data (1977-2009). Established reference conditions will thus incorporate natural spatial and temporal variability in fish assemblage characteristics, and together represent a best available standard of biotic integrity against which the current and future health of the estuary may be assessed and compared.
Values for the EHI are calculated for each main region of the Swan Estuary for each season and year, from data collected over the period 2007-2009, to establish and monitor trends in current estuarine health, and to validate the sensitivity and reliability of the index. It is envisaged that the index developed will provide managers with a reliable, practical and cost-effective method for assessing and communicating the health of the Swan Estuary.