Effects of tributyltin on survival, growth, morphometry, and RNA-DNA ratio of larval striped bass, Morone saxatilis.

Effects of tributyltin (TBT) on survival, growth, morphometry, and RNA-DNA ratio in larval striped bass (Morone saxatilis) were assessed in three experiments. In Experiment I, 13 day old larvae were exposed to 0, 0.067, 0.766, or 2.284 micrograms TBT/L for 6 days. All larvae exposed to 2.284 micrograms/L died by day 5; exposure to 0.766 micrograms/L significantly reduced survival relative to controls (59.8% vs. 81.8%). Significant, concentration-dependent decreases in body depth occurred in larvae exposed to 0.067 and 0.766 micrograms/L. In Experiment II, all 16 day old larvae exposed to 1.498 micrograms/L died by day 6. Survival, weight, and morphometry parameters were not significantly different in larvae exposed to 0, 0.052, or 0.444 micrograms/L for 6 days. In Experiment III, survival was similar in 21 day old larvae exposed to 0, 0.055, 0.281, or 0.514 micrograms/L for 7 days. Notochord length and dry weight decreased significantly in larvae exposed to 0.514 micrograms/L. Weight and morphometry parameters were more sensitive indicators of sublethal stress than RNA-DNA ratio. Maximum TBT concentrations reported in Chesapeake Bay marinas are likely to cause increased larval mortality. Longer-term studies are needed to assess effects at less than 0.050 micrograms/L, which may be more representative of habitat conditions.