Flowthrough Bioassay Studies on the Effects of Antifouling TBT Leachates

Abstract

The effects of tributyltin (TBT) exposures ranging from 1.4 to 2500 ng l-1 were examined on a broad spectrum of shallow-water organisms in long-term flowthrough bioassay tests performed at Hawaii and San Diego sites. Tributyltin was obtained as leachate from panels coated with various antifouling paints. Mature fouling communities at Hawaii sustained major reductions in species and individual abundances at TBT exposures ⩾500 ng l-1. Taxa most severely affected were those of low phyletic level and species with a high surface area of soft integument. TBT concentrations ⩾100 ng l-1 caused significant reductions in settling epifauna of low phyletic level. Hawaiian infauna experienced abundance reductions of ~ 50% at 500 ng l-1 TBT. Affected groups included nematodes, polychaetes, tanaids, isopods, bivalves, ophiuroids, and sipunculids. Abundances and mortality of benthic algae, macrocrustaceans, and fish were unaffected by TBT concentrations up to 2500 ng l-1. Bioconcentration of TBT was found to be very low in swimming crabs and moderate in anchovy fish. Adult American oysters of the Hawaii experiments were unaffected by TBT exposures up to 1800 ng l-1 and showed TBT bioconcentration factor (BCF) values that were inversely dose dependent, ranging from 19 600 to 35 000 at TBT exposure levels of 82 and 2 ng l-1, respectively. Reduced growth occurred in San Diego juvenile bay mussels at 70 ng l-1 TBT; and their BCF values were inversely dose dependent, ranging from 23 000 to 66 000 for TBT treatments of 450 to 6 ng l-1, respectively. In spite of possible captivityinduced stress during San Diego tests, juvenile American, European, Olympic, and Pacific oysters showed no growth effects from TBT exposures ⩽200 ng l-1. Growth rates and survival of adult Pacific oysters during Hawaii tests were slightly reduced by TBT concentrations of 13 and 29 ng l-1. However, those oysters may also have been nutritionally stressed as indicated by growth, survival, and condition indices of tank oyster controls, which were substantially lower than those of field controls. Pacific oyster BCF values were inversely dose dependent and ranged from 31 600 to 88 000 for TBT exposures of 29 to 14 ng l-1, respectively.