ACUTE AND CHRONIC TOXICITY OF TRIBUTYLTIN (TBT) TO PEDIVELIGER LARVAEOF THE BIVALVE SCROBICULARIA-PLANA

A static renewal test was run for 30 d to assess the effects of the an tifoulant tributyltin (TBT, nominal concentrations of 50, 125, 250 and 500 ng Sn l(-1)) on the survival and growth of 240 mu m-long pediveli ger larvae of the bivalve Scrobicularia plana (da Costal settling in f ine sand. Exposure to nominal TBT levels of > 125 ng Sn l(-1) (actual range of 37 to 102 ng Sn l(-1), as analysed) resulted in substantial m ortalities and negligible shell growth of individuals. More importantl y, larval shell growth at the lowest concentration tested (i.e. nomina l 50 ng Sn l(-1) or 14 to 32 ng Sn l(-1), as analysed) was significant ly reduced (by a factor of similar to 4) and grossly abnormal. In cont rast, some control postlarvae had begun developing siphons as they att ained a length of 600 to 700 mu m by the end of this test, thereby com pleting metamorphosis and becoming juveniles. The results are discusse d in relation to the widespread disappearance of S. plana in North Atl antic European estuaries during the 1980s and the concurrent TBT pollu tion in their waters. It is inferred that TBT is likely to have contri buted to the reported demise of clam populations by preventing the suc cessful and timely progress of their pediveliger larvae.