Benthic foraminiferal colonization in experiments with copper-contaminatedsediments

Colonization experiments, carried out over a 32-week period at 63 m water d epth in the Oslofjord, Norway, have shown that sediment Cu-concentrations o f >900 ppm cause a change in the living (stained) foraminiferal community s tructure as compared to control values of 70 ppm, The changes, which are re vealed through multivariate statistical analyses (MDS-ordination and ANOSIM tests) of the different treatment assemblages, are reflected by increased equitability and reduced abundances in treatments with high (967-977 ppm) a nd very high (1761-2424 ppm) Cu-concentrations. At the species level, a sig nificant negative effect of the Cu-enrichment could be observed only for St ainforthia fusiformis and Bolivinellina pseudopunctata, There was no signif icant decrease in the number of species with increasing sediment Cu-enrichm ent. This indicates that not even sediment [Cu] > 2000 ppm had a severe neg ative impact on the foraminiferal species ability to colonize, One prominen t effect of the Cu-contamination is that, at concentrations higher than abo ut 900 ppm, the opportunistic and dominant S. fusiformis developed an incre asingly patchy distribution pattern. Cu-contaminated sediments alone do not seem to promote development of deformed hard-shelled foraminiferal tests b eyond the normal range.