Long-term exposure to 4-nonylphenol affects sexual differentiation and growth of the amphipod Corophium ¨olutator Pallas, 1766/

Concern has been growing recently over the aquatic toxicity and reproductive effects of the non-ionic surfactant 4-nonylphenol NP.. NP appears to interact with development in some crustaceans. Using exposure response experiments based on nominal NP concentrations, the 96-h LC for adult Corophium ¨olutator, was 1670 mg ly1 50 95% Cl 1370]2170 mg ly1.. Juveniles were subsequently exposed to sublethal concentrations of NP for 120 days and effects on growth, sexual differentiation and reproduction were assessed. At the lowest NP exposure of 10 mg ly1 the density of surviving amphipods was reduced and growth was retarded. Fertility of female C. ¨olutator increased in NP exposed populations. Sex ratio was not affected by NP exposure, however, the second antennae of exposed male animals were significantly longer than those of control animals P-0.001.. It is hypothesised that NP may act via the androgenic gland which controls the development of male secondary sex characteristics in crustaceans. Males with large antennae are potentially at a selective disadvantage in the wild being more vulnerable to predation.