Effects of metal contamination on macrobenthos of two North Sea estuaries

Time series of faunal data for the Tyne (1978-1989) and the Tees (1981-1992) estuaries were analysed using Bray-Curtis similarity indices and dendrogram plots, multidimensional scaling, and principal components analysis (PCB). These data show that benthic community structure changed during the 1980s. Data on sediment heavy metal concentrations in the Tees estuary For the period 1971-1986 show significant reductions in contamination across this period, and also between-station differences. PCA of faunal data showed grouping of stations into marine, estuarine, and contaminated clusters. PC axis 1 appeared to be controlled by position of sampling site in relation to sources of contamination, and PC axis 2 by salinity. However, sediment metal concentrations were not significantly correlated with PC axis 1 scores. Reasons for this are discussed. Changes in the benthos indicate improving environmental quality, suggesting that clean-up initiatives in both estuaries have been effective. (C) 1996 International Council for the Exploration of the Sea