Ecological quality assessment of small estuaries from the Portuguese coast based on fish assemblages indices

► we five small estuaries with different levels of anthropogenic pressures were studied. ► Fish-based multimetric indices were used to differentiate ecological conditions. ► The correspondence of indices results to anthropogenic pressures was examined. ► Systems with equal levels of pressure were assign with different ecological status. ► Indicators were unable to distinguish natural from anthropogenic perturbations.