Sediment toxicity, contamination and amphipod abundance at a DDT‐ and dieldrin‐contaminated site in San Francisco Bay

Abstract

AbstractSediment toxicity to the amphipod Eohaustonus estuanus, sediment contamination, and the abundance of amphipods were examined along a contamination gradient in the Launtzen Channel and adjacent parts of Richmond Harbor, Call forma Dieldnn and DDT were formulated and ground at this site from 1945 to 1966 Sediment contamination by both dieldrin and the sum of DDT and its metabolites (EDDT) was positively correlated with sediment toxicity and negatively correlated with the abundance of amphipods excluding Grandidierella japonica The maximum dieldnn and ΣDDT concentrations in toxic units were 0 018 and 9 43, respectively, indicating that ΣDDT was the dominant ecotoxicological factor Concentrations of PAHs, PCBs, and metals were not sufficient to cause appreciable toxicity, except at one PAH contaminated station Relations between ΣDDT, sediment toxicity, and amphipod abundance are similar at three ΣDDT contaminated sites The 10 d LC50 for ΣDDT in field‐collected sediment was 2,500 μg/g organic carbon (OC) for Eohaustonus estuanus in this study, 1,040 μg/g OC for Rhepoxymus abromus exposed to Palos Verdes Shelf, California, sediment, and 2,580 μg/g OC for Hyalella azteca exposed to sediment from a freshwater stream system near Huntsville, Alabama The threshold for 10 d sediment toxicity occurred at about 300 μg ΣDDT/g OC The abundance of amphipods (except Grandidierella japonica) was reduced at EDDT concentrations > 100 μg/g OC Correlations between toxicity, contamination, and biology indicate that acute sediment toxicity to Eohaustonus estuanus, Rhepoxymus abromus, or Hyalella azteca in lab tests provides reliable evidence of biologically adverse sediment contamination in the field