Sandy-substrate microcosm studies on tributyl tin (TBT) toxicity to marine organisms
A.R. Beaumont, P.B. Newman, D.K. Mills, M.J. Waldock, D. Miller and M.E. Waite

A four month trial was carried out using a series of sandy-substrate flow through microcosms containing two bivalve species (Cerastoderma edule and Scrobicularia plana), two polychaete species (Nereis diversicolor and Cirratulus cirratus), a crustacean (Corophium volutator) and a gastropod (Littorina littorea). Small specimens of other invertebrate species may have been present initially in the sand which was sieved down to 2 mm and, during the trial, larvae and post-larvae of other invertebrates entered the microcosms with the water supply. TBT was introduced into three microcosms at high (1-3 mg l-1) and three at low (0.06-0.17 mg l-1) concentrations by using a header tank containing panels painted with "Micron 25" (International Paints Ltd.) anti-fouling paint. High TBT concentrations killed all adult bivalves within a few weeks and the low level TBT produced complete mortality of cockles after 4 months. The introduced adult polychaetes were generally resistant to TBT and no significant mortalities were observed for L. littorea. No C. volutator specimens were recovered from any microcosms probably due to their migration through the outflow. A 1000 to 15 000 fold accumulation of TBT was recorded in the tissue of the bivalves. Chlorophyll- a analysis of core samples revealed significant benthic microalgal production in all microcosms with greatest production in high TBT. However, the high TBT microcosms contained virtually no animal life and therefore the algae were not grazed. Up to 16 species of non-introduced invertebrates were found in the low level TBT and control microcosms, but total bivalve biomass (numbers and size) was significantly greater in the controls than at the low level of TBT. This study confirms the very high toxicity of TBT to adult bivalves and to the larvae of many marine invertebrates and demonstrates that current levels of TBT (0.05-2 mg l-1) in areas of high pleasure craft activity may be having a significant deleterious effect on marine life.

Keywords: TBT, toxicity, microcosms, bivalves, polychaetes.
Contents of this volume Sci. Mar. 53(2-3) : 737-743 Back PDF
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