Long-term exposure to 4-nonylphenol affects sexual differentiation and growth of the amphipod Corophium volutator (#Pallas, 1766)

Abstract

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 50 for adult Corophium volutator, was 1670 μg l −1 (95% Cl 1370–2170 μg l −1). 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 μg l −1 the density of surviving amphipods was reduced and growth was retarded. Fertility of female C. volutator 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.