Effects of methylmercury on sperm and egg viability of two populations of killifish (fundulus heteroclitus)

Exposure of sperm of killifish (Fundulus heteroclitus) from a relatively clean area in Long Island (LI) to 0.01 mg/L methylmercury (meHg) in 15%o sea water caused significant reduction of fertilization success. However, exposure of killifish sperm from polluted Piles Creek (PC) to either 0.01 or 0.05 mg/L meHg in 15%o sea water prior to insemination had no effect on fertilization success. Exposure of LI killifish sperm to 0.05 mg/L meHg caused significant reduction in motility. However, PC killifish sperm showed no significant difference in motility between 0 and 0.05 mg/L meHg exposure. Exposure for 5 min to 0.05 mg/L meHg caused significant reduction in motility. These data indicate that meHg is less toxic to PC killifish sperm than LI killifish sperm. Exposure of PC and LI killifish sperm to 0.05 mg/L meHg for 15 min had no effect on sperm morphology. PC killifish sperm also showed higher (20 min) motility in 15%o sea water than LI killifish sperm (10 min). Exposure of PC and LI killifish eggs up to 25 min to 0.05 mg/L meHg prior to fertilization had no effect on fertilization success.