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Swimming performance and predator avoidance by mummichog ( Fundulus heteroclitus ) larvae after embryonic or larval exposure to methylmercury

1995; Canadian Science Publishing; Volume: 52; Issue: 10 Linguagem: Inglês

10.1139/f95-809

1205-7533

Judith S. Weis, Peddrick Weis,

Aquatic life and conservation

Embryos of the mummichog, Fundulus heteroclitus, were exposed to 5 and 10 μg/L methylmercury throughout development; these are concentrations below those that cause teratological effects. Larvae were maintained in clean seawater or in water with methylmercury, and tested for swimming performance by chasing them with a glass rod. Swimming performance improved with larval age. Larvae that had been exposed to methylmercury as embryos swam greater distances than controls, while those that were exposed only as larvae swam less than controls. The effects of the embryonic exposure diminished over time, and the larval environmental conditions took precedence. Larvae were also tested with two predators, the grass shrimp, Palaemonetes pugio, and 1 -year-old mummichogs. Those that had been exposed to mercury as embryos (which swam more than controls) or as larvae (which swam less than controls) were more susceptible to predation than controls. The increased swimming of those exposed as embryos may have reflected greater activity, making them more likely to attract the predator's attention, while the slower swimming of those exposed as larvae could make them easier to capture.