Marine Pollution Bulletin. Volume 26. No. 7, pp. 380-384, 1993. Printed in Great Britain. Imposex in Lepsiella vinosa from Southern Australia Marine Pollution Bulletin 111)25-326x/93S6.1)o+o.oo © 1993PergamonPressLtd DEBORAH J. NIAS*t§, STEPHEN C. McKILLUP*~: and KAREN S. EDYVANEt *Department of Zoology, University of Adelaide, G.P.O. Box 498, Adelaide, South Australia, 5001, Australia +South Australian Department of Fisheries, G.P.O. Box 1625, Adelaide, South Australia, 5001, Australia §To whom correspondence should be addressed at the South Australian Department of Fisheries. ~-Present address: Department of Biology, University of Central Queensland, Rockhampton, Queensland, 4702 Australia. The deformity 'imposex', which is the growth of a penis and/or vas deferens in females of dioecious gastropods, has been associated with the use of tributyltin based marine antifouling paints. We report on a survey of Lepsiella vinosa in Southern Australia which detected imposex at 14 of 20 sites sampled. Laboratory experiments suggested that although tributyltin is important in the development of imposex, other factors including copper, paint matrix and environmental stress may also induce this deformity. Since the mid 1960s, the most effective and commonly used antifouling paints have contained organotin compounds such as tributyltin (TBT) (Lau, 1991). TBT has been shown to affect 'non-target' organisms at nano- molar concentrations. Effects include shell curl and weight loss in oysters (Batley et aL, 1989), histopatho- logical changes in fish (Wester et al., 1990), mortality of invertebrates in Thalassia seagrass ecosystems (Kelly et al., 1990a,b) and 'imposex' in whelks (Bryan et aL, 1986). 'Imposex' is the appearance of male reproductive parts (a vas deferens and/or a penis), in females of normally dioecious species. This deformity has been observed in 72 species of gastropods belonging to 49 genera, especially Neogastropod whelks (Oehlmann et al., 1991), and may have two serious consequences. Firstly, imposex is irreversible in Nucella lapillus and probably also in other species (Bryan et al., 1987). Secondly, the growth of a vas deferens can cause steril- ization of the female by blocking the genital pore, thereby having the potential to reduce the reproductive output of a population (Bryan et al., 1987). Most published studies on imposex are from the British Isles and North America. In South Australia many boat moorings and commercial boating channels are close to rocky intertidal habitats, estuaries or mangrove forests, so it is likely that gastropods in these areas have been exposed to organotin compounds and may therefore show signs of imposex. Furthermore, exposure to TBT may have resulted in changes to the population structure of these species. The intertidal muricid gastropod Lepsiella vinosa (Lamarck) is common in a variety of habitats in South 380 Australia, including rocky shores, amongst mangroves and in estuaries (Shepherd & Thomas, 1989). We examined L. vinosa from southern Australia for evidence of imposex and whether there were differences in population structure amongst sites which were correlated with the probable degree of exposure to TBT. The effects of TBT and TBT and copper based anti- fouling paints upon female L. vinosa were also examined in the laboratory. Materials and Methods Survey for imposex in L. vinosa Lepsiella vinosa was collected from 18 sites in South Australia and two in Victoria between February and November 1991 (Fig. 1). Whelks could only be sexed by dissection and the number of individuals collected varied amongst sites, but at least 19 females were collected from all but two sites. At every site the approximate number of boats and the environment (mangrove, sandflat or rocky intertidal) were noted. Whelks were taken to the laboratory, placed in clean aerated seawater and dissected within two days. Shell length was measured to the nearest 0.1 mm using vernier calipers, the shell cracked in a vice and gently removed before examining the body of the whelk under a binocular microscope at 40x magnification. Experimental induction of imposex in Lepsiella vinosa Exposure to tributyltin chloride. Lepsiella vinosa were collected from a population at Middle Beach, South Australia (site 11 on Fig. 1) which we had decided was free of imposex after failing to detect it in any of 50 females. It was not possible to sex L. vinosa except by dissection, so fifty unsexed individuals were assigned at random to each of 20 glass aquaria. By inspection the random allocation resulted in a range of comparable sizes of whelks in each aquarium. Four aquaria were randomly allocated to each of five treatments; exposure to zero, 1 ng, 10 ng, 100 ng and 500 ng TBT per litre of seawater. All treatments included the control of zero TBT also contained approximately 0.00009 N acetic acid, since it was necessary to dissolve TBT in 18 N glacial acetic acid to make it soluble in seawater. Aquaria were kept aerated (dissolved oxygen was not measured) at 23°C in a temperature controlled room.