The level of taxonomic discrimination required to detect pollution effects on marine benthic communities

Abstract

Five data sets (three for macrobenthos and two for meiobenthos), describing the species composition of benthic assemblages in relation to pollution gradients, have been subjected to multivariate and univariate analysis, using various hierarchical levels of taxonomic aggregation of the species data. In no case was there any substantial loss of information at the family level. Identification of the fauna to this level would obviate most of the time-consuming problems associated with the analysis of benthic samples for the purposes of assessing pollution effects. Sample groupings in the multivariate analyses of the macrofauna data related more closely to the pollution gradient at the level of phyla than of species in two of the three examples, and the relationship was no worse for phyla in the remaining example. It is tentatively suggested that anthropogenic effects modify community composition at a higher taxonomic level than natural environmental variables, which influence the fauna more by species replacement. This differential response could be potentially useful in separating pollution effects from those of natural environmental variables such as water depth and sediment type.