EFFECTS OF TRIBUTYLTIN (TBT) AND TESTOSTERONE ON THE FEMALE GENITAL SYSTEM IN THE MESOGASTROPOD LITTORINA-LITTOREA (PROSOBRANCHIA)

Experiments were performed with the mesogastropod Littorina littorea o n Helgoland, in Roscoff, and in the laboratory in order to evaluate th e reaction of the female genital system to TBT, an environmental toxic ant. The snails were either injected with 50 or 100 ng tributyltin (TB T) soluted in ethanol or exposed to artificial sea water treated with 5, 50, 100, and 200 ng TBT/l, and 33 ng testosterone/l. The duration o f the experiments was either four or eight weeks. None of the analysed female L. littorea showed signs of imposer. Compared to results for t he control groups, the size of the female glandular complex was signif icantly reduced if the pre-experimental toxication was already high, a s is the case in snails collected around Helgoland. TBT-related gland complex reduction occurs also in female L. littorea from other samplin g sites. In addition, injection of ethanol also causes a decrease in g land size. The experimental results demonstrate that the distal female genital system responds with significantly lower sensitivity to TBT t han that of other prosobranchs. This behaviour is ascribed to the lack of an androgen receptor at the ovipositor. The results further streng then the case of the extreme rarity of imposer described for female L. littorea in natural habitats. However, strong TBT-toxication may affe ct L. littorea populations significantly because of increasing masculi nization of the females, which reduces reproduction ability.