Effects of tributyltin exposure in the embryonic stage on sex ratio and survival rate in the caprellid amphipod Caprella danilevskii

Abstract

In order to examine the biological effects of tributyltin (TBT) exposure, the caprellid amphipod Caprella danilevskii was exposed to 5 levels (0, 10, 100, 1000 and 10 000 ng l -1 ) of TBT dur- ing the embryonic stage (5 d). The male and female ratios changed dramatically in the hatched juve- nile with increases in TBT concentrations; i.e. the proportion of females was found to increase to 55.6% at 10 ng l -1 , 85.7% at 100 ng l -1 and 81.8% at 1000 ng l -1 . All specimens died in 10 000 ng TBTCl l -1 within 5 d after spawning due to the acute toxic concentration for the species. No signifi- cant differences were observed to occur in the sex ratio in response to the exposure after hatching (50 d) in a previous study. Sex disturbance might therefore be induced during the embryonic stage in the caprellid. Reproductive inhibitions such as brood loss and oogenesis inhibition occurred even at 10 to 100 ng TBTCl l -1 exposures in the short term in both parental females and their offspring females. The survival rate decreased drastically as the TBT concentrations increased, with the decrease being observed at TBT concentrations as low as 10 ng l -1 (69%) in the offspring. In parental females, the survival rate also decreased at more than 100 ng TBTCl l -1 , despite movement after 5 d into the no-TBT-added seawater. Therefore, our data suggest that nanogram concentrations of TBT similar to those encountered in coastal waters can directly affect sex ratio, reproduction and survival in the caprellid, and this phenomenon occurs at environmentally realistic concentrations in the coastal ecosystem.