Imposex in Reishia clavigera as an Indicator to Assess Recovery of TBT Pollution After a Total Ban in South Korea

The temporal changes in the frequency and degree of imposex and tributyltin (TBT) levels in gastropod (Reishia clavigera) were evaluated in Jinhae Bay, 5 and 10 years after the total ban on TBT usage in South Korea. The frequency and degree of imposex decreased significantly after the ban, accompanied by an increase in the female-to-male ratio. The TBT concentrations in R. clavigera also decreased significantly after the ban. There were good correlations between the TBT concentration in rock shell and both the degree of imposex and the female-to-male ratio. The total TBT ban effectively reduced the TBT levels and the frequency and degree of imposex in R. clavigera. However, the current low exposure level in the study area is still sufficient to cause imposex in R. clavigera. More time is needed to reduce the TBT levels to levels that do not have adverse biological effects on R. clavigera.