BEHAVIORAL-EFFECTS IN MUMMICHOG LARVAE (FUNDULUS-HETEROCLITUS) FOLLOWING EMBRYONIC EXPOSURE TO METHYLMERCURY

Embryos of the mummichog, Fundulus heteroclitus, were exposed to conce ntrations of methylmercury (meHg) below those that can cause morpholog ical abnormalities. After hatching, larvae were kept in clean water an d tested periodically for ability to capture prey (Artemia salina) or for their swimming performance and predator avoidance. Embryonic expos ure to 10 mu g/liter meHg resulted in reduced prey capture ability by early larvae, measured as total Artemia caught in 1 and 5 min. However , older larvae recovered from the behavioral deficits, perhaps owing t o a compensation for early CNS insult. Fish from a chronically pollute d environment (Piles Creek (PC), a tributary of the Arthur Kill), prev iously shown to have high tolerance to the teratogenic effects of high er concentrations of meHg, proved to be less susceptible to these beha vioral effects than fish from a relatively uncontaminated site (EH). A lso, the PC control larvae captured prey far more effectively than the EH larvae, although they made more miscues. Wizen tested for swimming performance after embryonic exposure to 10 mu g/liter, EH larvae had increased performance when compared to controls. This effect was also transitory. The improved swimming performance did not correspond to im proved ability to avoid predation by grass shrimp (Palaemonetes pugio) . The increased swimming performance may correspond to greater total a ctivity, making them more likely to attract the predator's attention a nd resulting in increased capture. Thus, negative, though temporary, e ffects were observed in both prey capture and predator avoidance after embryonic exposure to meHg. Copyright (C) 1996 Elsevier Science Ltd