Abnormalities in sexual development of the amphipod Gammarus pulex (L.) found below sewage treatment works

Increasing numbers of widely used industrial, agricultural, and natural che micals are known to elicit endocrine-disrupting effects in a wide range of vertebrate and invertebrate species. The objective of this study was to det ermine whether the sexual development of the freshwater crustacean Gammarus pulex (L.) was affected below sewage treatment works (STW) previously know n to contain endocrine-disrupting chemicals in their effluent. The,gonadal structure, external sexual characteristics, and size of gammarids from expo sed sites were compared to those of gammarids from a reference site. No sig nificant difference was found in the gonadal structure of males collected b elow two STW. However, a highly significant number of females collected fro m a site known to elicit high estrogenic responses in vertebrates displayed an abnormal structure of oocytes in vitellogenesis. Body size was signific antly shorter and male/female size differential was significantly reduced b elow one of the STW. Analysis of gnathopod and genital papillae length data suggests that different allometric relationships of these organs to body s ize exist between sample sites.