The relationship between trace metal contamination and stream meiofauna

The effect of chemical contaminants on freshwater meiofaunal communities is poorly understood and meiofauna rarely form part of environmental impact assessments in fresh waters. The community composition and diversity of meiofauna in streams of southwest England (Cornwall) representing a gradient in trace metal contamination were investigated. Multivariate and univariate statistical techniques were used to correlate community composition, diversity and environmental variables. Meiofaunal communities were very different at sites with high compared with low metal concentrations. Copper, either singly, or in combination with other environmental variables (aluminium, zinc or dissolved organic carbon), was the most important correlate with community composition. Not all meiofaunal species were adversely affected by metals, however, and some taxa, most notably certain cyclopoid copepods, were abundant at high metal concentrations. Moreover, sites with high metal concentrations were not significantly less diverse than sites of low metal concentrations. These data suggest that metal contamination significantly alters the composition of stream meiofaunal assemblages and highlight the importance of including meiofauna in impact studies of fresh waters.