Response of multi-metric indices to anthropogenic pressures in distinct marine habitats: The need for recalibration to allow wider applicability

Sustainable exploitation of coastal ecosystems is facilitated by tools which allow reliable assessment of their response to anthropogenic pressures. The Infaunal Quality Index (IQI) and Multivariate-AMBI (M-AMBI) were developed to classify the ecological status (ES) of benthos for the Water Framework Directive (WFD). The indices respond reliably to the impacts of organic enrichment in muddy sand habitats, but their applicability across a range of pressures and habitats is less well understood. The ability of the indices to predict changes in response to pressures in three distinct habitats, intertidal muddy sand, maerl and inshore gravel, was tested using pre-existing datasets. Both responded following the same patterns of variation as previously reported. The IQI was more conservative when responding to environmental conditions so may have greater predictive value in dynamic habitats to provide an early-warning system to managers'. Re-calibration of reference conditions is necessary to reliably reflect ES in different habitats.