INHIBITION OF BARNACLE SETTLEMENT BY THE ENVIRONMENTAL ESTROGEN 4-NONYLPHENOL AND THE NATURAL ESTROGEN 17-BETA ESTRADIOL

The present study examines the effect of a known environmental oestrog en, 4-nonylphenol, on the settlement of the cypris larva of the barnac le, Balanus amphitrite. Cypris larvae were exposed to 4-nonylphenol in a nominal concentration range of 0.01-10.0 mu g l(-1). Definitive con centrations of 4-nonylphenol in the test solutions were determined by GC/MS, Cyprid settlement was reduced significantly within this concent ration range, following incubation at both 25 degrees C and 28 degrees C for 24-48 h. A naturally occurring oestrogen, 17 beta oestradiol, w as used as a positive control, in the concentration range 0.01-10.0 pg l(-1). Larval settlement was inhibited by 17 beta oestradiol, but the trend was the opposite to that seen with 4-nonylphenol. No evidence o f endocrine disruption was demonstrated, but significant inhibition of larval settlement by both 4-nonylphenol and 17 beta oestradiol indica ted that the compounds may have toxic effects at environmentally reali stic and naturally occurring concentrations. The potential for endocri ne disruption being more significant at different developmental stages in barnacles is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.