An overview of the assessment of aquatic ecosystem health using benthic invertebrates

Community structure or species composition of benthic invertebrates has frequently been used in environmental monitoring and assessment of aquatic systems. Three general approaches have been taken: the ‘saprobic’ approach, which requires detailed knowledge of taxonomy and is most effective in measuring impacts from sewage effluents; diversity indices, which do not require detailed knowledge of species requirements but ignore information provided by important species and tend to lose information; and biotic indices, which combine both approaches. In the past few years considerable advances have been made by applying multivariate statistical techniques to large data matrices and relating benthic community structure to key environmental variables. Using these techniques it is possible to establish reference communities for a set of environmental conditions, to predict the benthic community that should occur at new sites and thus measure deviation from an expected community type. This suggests that environmental criteria and objectives can be established based on biological variables as opposed to the more traditional chemical approach.Measurement of ecosystem health using functional attributes of benthic invertebrates is generally in the development stage. In the future, functional measures of ecosystem health, such as chronic measures of toxicity or stress, should be incorporated into any assessment process.