Effects of embryonic exposure to methylmercury on larval prey‐capture ability in the mummichog, fundulus heteroclitus

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Abstract
Embryos of the mummichog (Fundulus heteroclitus) were exposed to 2, 5, or 10 m̈g/L methylmercury (meHg) throughout development; these are concentrations below those which cause teratological effects in this species. After hatching, larvae were maintained in clean seawater and tested for prey‐capture ability, using Artemia salina nauplii. Larvae that had been exposed to 10 m̈g/L methylmercury (and in two out of three trials, 5 m̈g/L) initially exhibited slower prey‐capture ability than did the other groups. This is an indication of a subtle functional impairment due to the toxicant (“behavioral teratology”). However, the effect was transitory, and by about 1 week after hatching the prey capture of these larvae equalled that of the controls and the other treated groups. Growth of these larvae was also comparable to that of controls. The exposure may have caused retardation of neurological development, which was subsequently compensated for, and therefore no long‐lasting effects were produced. In the field, however, embryos exposed to toxicants would probably continue to be exposed as larvae, and might not have the opportunity to recover from the deleterious effects, but rather might have them augmented.