PNNL

Abstract

Exposure of ?shes to environmental estrogens is known to affect sexual development and spawning, but little information exists regarding effects on gametes. This study evaluated embryonic survival of offspring from male rainbow trout (Oncorhynchus mykiss) exposed to 17a-ethynylestradiol (EE2)using an in vitro fertilization protocol. Males were exposed at either 1800 or 6700 degree days (8d) (i.e. 161 or 587 days post-fertilization (dpf)) to test for effects on testes linked to reproductive ontogeny. At 18008d, ?sh were beginning testicular differentiation and were exposed to 109 ng EE2/l for 21 days. At 67008d, ?sh have testes containing spermatocytes and spermatids and were exposed for 56 days to either 0.8, 8.3, or 65 ng EE2/l. Semen was collected at full sexual maturity in each group and used to fertilize eggs pooled from several non-exposed females. Signi?cant decreases in embryonic survival were observed only with the 67008d exposure. In 0.8 and 8.3 ng EE2/l treatments, embryo survival was signi?cantly reduced at 19 dpf when compared with the control. In contrast, an immediate decrease in embryonic survival at 0.5 dpf was observed in the 65 ng EE2/l treatment. Blood samples collected at spawning from 67008d exposed males revealed a signi?cant decrease in 11-ketotestosterone and a signi?cant increase in luteinizing hormone levels for the 65 ng EE2/l treatment when compared with the other treatment groups. Results indicate that sexually maturing male rainbow trout are susceptible to EE2 exposure with these ?sh exhibiting two possible mechanisms of reduced embryonic survival through sperm varying dependant