EFFECTS OF TRIBUTYLTIN (TBT) EXPOSURE ON THE VELIGER LARVAE DEVELOPMENT OF THE BIVALVE SCROBICULARIA-PLANA (DACOSTA)

Laboratory-obtained veliger larvae of the bivalve Scrobicularia plana were used to test the toxicity of the antifoulant tributyltin (TBT) by means of a static renewal trial which monitored larval survival and g rowth as influenced by nominal TBT concentrations of 50, 125, 250 and 500 ng Sn . 1(-1) during 10-day exposure. While S. plana veligers (mea n initial shell length = 100 mu m) were found to develop to pedivelige rs (mean length = 230 mu m) in 10 days under control culture condition s, all levels of TBT tested significantly reduced the veliger growth r ate (by a factor of greater than or equal to 2.7); probable lethal eff ects of nominal levels greater than or equal to 250 ng Sn . 1(-1) coul d not be demonstrated because of reduced larval survival in the solven t control. The results are discussed in relation to the widespread dis appearance of S. plana in North Atlantic European estuaries during the 1980s and the concurrent TBT pollution in their waters. It is conclud ed that TBT has probably contributed to the reported demise of clam po pulations by preventing the successful and timely development of their veliger larvae.