Predator avoidance in mummichog larvae from a polluted habitat

Abstract

Previous work has shown that adult mummichogs (Fundulus heteroclitus) from a polluted site (Piles Creek, PC, New Jersey) were more vulnerable to predation by blue crabs than fish from a more pristine site (Tuckerton, TK, New Jersey). The present study was conducted to compare the spontaneous activity, swimming performance and predator avoidance of fish of the two populations at early life stages. When raised in synthetic salt water, both newly hatched and 1–month‐old mummichog larvae from TK had greater spontaneous activity, swimming performance, and stamina than those from PC. In comparison to TK, PC larvae were less vulnerable to predation by yearling mummichogs at 1 week old, but were more vulnerable at 1 month old. Variation in behaviour and swimming ability of TK and PC larvae accounted for the differences in vulnerability to predation. TK larvae employed greater swimming and irregular movement, which was more successful for survival of older larger larvae. In contrast, PC larvae hid, often remaining motionless, which was advantageous for survival of young smaller larvae. Contaminants had been assumed responsible for the behavioural differences in the PC population. However, since differences were seen in larvae raised in synthetic salt water, it is possible that maternally transferred neurotoxicants (possibly delayed effects) and/or inherent factors also play a role.