Benthic invertebrate communities are good indicators of organic pollution and are also sensitive to toxic pollutants. They are ideally suited to biological monitoring as they are sedentary and either feed upon sediment dwelling animals or the sediment . They are also relatively long-lived (more than one year) so will react to contaminant effects over time. This method is based on the principle that different benthic invertebrates have different tolerances to pollutants.
The Infaunal Quality Index (IQI) enables an assessment of the ecological health of the biological quality element benthic invertebrate fauna.
The method statement published in 2008 for the first river basin planning cycle has now been updated for the second cycle, linked below.
"Infaunal quality index: WFD classification scheme for maine benthic invertebrates" is a supporting technical document that describes the development of the method.