Effects of DDT sediment-contamination on macrofaunal community structure and composition in San Francisco Bay

The objectives of this study were to determine the effects of sediment contamination on the benthic macrofauna and to predict macrofaunal changes following remediation at a Superfund (uncontrolled hazardous waste) site in San Francisco Bay, California, USA. DDT and its metabolites (ΣDDT) were the contaminants of concern. With few small-scale exceptions, all (>100) other sediment contaminants ever measured at the site were present at background or non-toxic levels. In hierarchical regressions [Y=f(X1, X2, X3), where X1=sediment %silt + clay, X2=sediment total organic carbon (OC), and X3=log10 (ΣDDT μg g−1 OC)] with data from samples collected at the study site, log10(ΣDDT μg g−1 OC) explained a highly significant amount of the variance in the infaunal index (II ) and log10(number of Amphipoda excluding Grandidierella japonica + 1) after statistically controlling for the potential effects of sediment %silt + clay and OC. The ratios of change of II and log10(number of Amphipoda excluding G. japonica + 1) with respect to log10(ΣDDT μg g−1 OC) were about −9:1 and −0.4:1, respectively. Most of the 92 species collected were present at low to moderate densities over the entire range of ΣDDT sediment concentrations. The bivalve Theora lubrica, tubificids, most polychaetes, a tanaid (Zeuxo normani), and an amphipod (G. japonica), were common, while four other amphipods (Ampelisca abdita, Corophium heteroceratum, Photis brevipes, Dulichia rhabdoplastis), a phoronid (Phoronis cf. pallida), a bivalve (Cryptomya californica), and a cumacean (Eudorella pacifica), were rare or absent from sites with high ΣDDT sediment-concentrations.