Effects of tributyltin maternal and/or waterborne exposure on the embryonic development of the Manila clam, Ruditapes philippinarum.

We examined the effect of tributyltin (TBT) on embryonic development of the Manila clam, Ruditapes philippinarum. In a maternal exposure test, 100 clams were exposed to TBT at measured concentrations of <0.01 (control), 0.061, 0.310, or 0.350 microg/l at 20-22 degrees C for 3 weeks, and the embryo developmental success (the ratio of normal D-larvae to all larvae) was measured. There was a significant negative correlation between embryo developmental success and TBT concentration in the female Manila clams (p < 0.001). These results indicated that TBT accumulated in the female clam decreased embryo developmental success. In a waterborne exposure test, fertilized eggs (4 h after fertilization) were exposed to TBT at measured concentrations of <0.01 (control), 0.062, 0.140, 0.320, or 0.640 microg/l for 23 h. Embryo developmental success was also significantly decreased in all TBT treatment groups compared with that in the control group. TBT accumulated in female adults and waterborne TBT clearly inhibit reproductive success of the clam.