Annual accumulation cycle of butyltin compounds in oysters according to egg production

Abstract

Organotin compounds are one of the most widely used organometallic chemicals. They are actively applied to antifouling paints as biocidal additives to prevent adherence of sedentary organisms to ship hull and other structural surfaces immersed in water. Since their deleterious effects on non-target organisms were revealed in the early 1980&apos;s, many industrialized countries have placed regulations of ban on use of organotin compounds, especially tributyltin (TBT) compound, in ships. South Korea is one of the major ship building industries in the world, and boating activities are relatively high as a peninsula. Korean government has banned the use of TBT based antifouling paint on ships less than 400 tonnage from 2000 and whole ships from 2003. Bivalve organisms such as oysters have been used as monitoring organisms due to their high accumulation of butyltins, sessile characteristics and wide distribution. However, annual accumulation pattern of TBT and its degradation products were not revealed yet. Seasonal fluctuation of butyltin compounds in oysters is crucial to monitor butyltin residue for regional and annual comparison. In this study, TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT) were quantitatively determined in oysters from aquaculture farm in Goseong from Jan. to Dec. in 2000. TBT, DBT and MBT concentrations in oysters ranged 90 - 434 ng/g, 70 - 194 ng/g, and 47 - 214 ng/g. Butyltins residues in the oysters showed seasonal fluctuation, which is closely related to spring and autumn spawning events. After both spring and autumn spawning, all three butyltin concentrations decreased and then accumulated again in winter season. Egg weight was quantified in an individual female oyster using enzyme-linked immunosorbent assay. Tributyltin body burden in individual female oyster demonstrated a significant positive correlation (r2 = 0.87, p < 0.001) with its egg weight.