The use of benthic macroinvertebrates to establish a benchmark for evaluating the environmental quality of microtidal, temperate southern hemisphere estuaries

► Establishing benchmark data for a pristine seasonally-open estuary. ► Benthic faunas in a pristine and an eutrophic seasonally-open estuary differ markedly. ► Relative prevalences of polychaetes and crustaceans vary with level of eutrophication. ► Use of taxonomic distinctness to compare environmental quality across 17 estuaries.