Further Laboratory Studies of the Effects of Exogenous Oestrogenic Chemicals on Exposure Markers and Breeding Success in Sand Goby

The effects of oestrogenic exposure upon exposure indicators and reproductive success in a marine fish were investigated using a series of short and long-term exposures of the sand goby (Pomatoschistus minutus) to oestrogenic materials. A 140 bp cDNA probe for sand goby vitellogenin (VTG) was used to measure hepatic VTG mRNA expression. Effects on other novel and “classical” biomarkers of oestrogenic exposure were also investigated. Sand goby were exposed to 4-tert-octylphenol (OP) or 17β-oestradiol (E2) in continuous flow-through. Following six months exposure to E2, breeding trials were conducted to investigate effects upon individual and population reproductive output. In a 28-day doseranging exposure, OP induced hepatic VTG mRNA expression and VTG protein production at concentrations greater than 30 μg l. Prolonged exposure to OP (0–119 μg l) resulted in effects being seen that were responsive to both exposure concentration and duration. In the E2 exposure (0–530 ng l), the effects were responsive to exposure concentration, but not duration. With increasing exposure concentration, VTG mRNA expression increased, and indicators of male maturation (gonad size, sperm-duct gland size, nuptial colouration) either decreased or showed inhibited development. Population reproductive output was significantly reduced following exposure to 70 or 530 ng l E2, with no fertile eggs produced at the higher concentration. These concentrations also significantly elevated male VTG mRNA expression. This work suggests that wild goby populations exhibiting biomarkers of oestrogenic exposure are likely to have reduced reproductive success.