SEASONAL REPRODUCTIVE HEALTH OF FLOUNDER PLATICHTHYS-FLESUS EXPOSED TO SEWAGE EFFLUENT

Indicators of environmental oestrogen exposure in male and female wild flounder Platichthys flesus were followed over the annual reproductiv e cycle. Fish were obtained from the Tyne estuary, UK, which receives effluent from a large sewage treatment works and several other anthrop hogenic sources and the Solway Firth, UK, which receives only low leve ls of sewage effluent. Vitellogenin (vtg), a female-specific protein, was present in the plasma of up to 94 % of males from the Tyne and was accompanied by inhibited spermatogenesis and the incidence of patholo gical testicular abnormalities. The vtg levels in males are independen t of the seasonal cycle. Female flounders from the Tyne exhibited incr eased vtg levels and a higher proportion of degenerating oocytes than Solway Firth females. This study provides limited evidence that wild p opulations of flounders showing oestrogenic responses are also sufferi ng reproductive disturbances but the degree of alteration varies durin g the seasonal reproductive cycle.