Gastropod

TBT, like most other organic pollutants, is metabolized more rapidly by vertebrates than by aquatic invertebrates such as gastropods. 

Returning to the question of endocrine disruption, it is now known that over 100 species of gastropods worldwide suffer from a condition described as imposex, the development of male characteristics by females. It has already been established for some species (e.g., dog whelk) that TBT is the cause of this, and it is suspected that organotin compounds account for most cases of imposex worldwide (Matthiessen and Gibbs 1998). Some examples of masculinization of female gastropods caused by tributyltin are given in Table 8.4. 

Apart from gastropods, harmful effects of TBT have also been demonstrated in oysters (Environmental Health Criteria 116, Thain and Waldock 1986). Early work established that adult Pacific oysters (Crassostrea gigas) showed shell thickening caused by the development of gel centers when exposed to 0.2 pg/L of TBT fluoride (Alzieu et al. 1982). Subsequent work established the no observable effect level (NOEL) for shell thickening in this, the most sensitive of the tested species, at about 20 ng/L. It has been suggested that shell thickening is a consequence of the effect of TBT on mitochondrial oxidative phosphorylation (Alzieu et al. 1982). Reduced ATP production may retard the function of Ca++ ATPase, which is responsible for the Ca++ transport that leads to CaCOj deposition during the course of shell formation. Abnormal calcification causes distortion of the shell layers. 

Bryan, G.W., Gibbs, P.E., Hummerstone, L.G., and Burt, G.R. (1986). The decline of the gastropod Nucella lapillus around Southwest England—Evidence for the effect of tributyl-tin from antifouling paints. Journal of the Marine Biological Association of the United Kingdom 66, 611-640. 

Santos, M.M., Reis-Henriques, M.A., and Vieira, M.N. et al. (2006). Triphenyltin and tribu-tyltin, single and in combination, promote imposex in the gastropod Bolinus brandaris. Ecotoxicology and Environmental Safety 64, 155-162. 

The saxitoxins accumulated from the plankton by molluscan filter-feeders can be passed on to other animals. Gastropods such as whelks, which prey on bivalves, have been found to be toxic, apparently from consuming toxic bivalves (65). Such... 

Over 40 different types of polypeptide toxins have been found in marine animals (i). Many of these toxins are exquisitely selective in their actions, affecting a single process or receptor at minute concentrations. So far the sea anemone and gastropod Conus) toxins have attracted the most attention as molecular probes of ion channels. In this chapter, we discuss several approaches which are being used to investigate, at the molecular level, the interactions of the sea anemone neurotoxic polypeptides with sodium channels. 

Occurrence in molluscs of steroidogenesis along a pathway very similar to that found in vertebrates has been claimed. Testosterone (64) - androstenedione (65) interconversion has been demonstrated in gonads of the male and female bivalve - Mytilus edulis [117] and of the gastropod Crepidula fornicata [118], by using labelled testosterone and androstenedione. Moreover, several steroids have been identified in the gonads and hepatopancreas of the opisthobranch... 

Ramon M, Cano J, Pena BJ et al (2005) Current status and perspectives of mollusc (bivalves and gastropods) culture in the Spanish Mediterranean. Boletin Institute Espanol de Oceano-grafia 21 361-373... 

Bryan, G.W., W.J. Langston, L.G. Hummerstone, G.R. Burt, and Y.B. Ho. 1983. An assessment of the gastropod, Littorina littorea, as an indicator of heavy-metal contamination in United Kingdom estuaries. Jour. Mar. Biol. Assoc. U.K. 63 327-345. 

Copper compounds are used routinely and widely to control freshwater snails that serve as intermediate vectors of schistosomiasis and other diseases that afflict humans (Hasler 1949 NAS 1977 Rowe and Prince 1983 Winger etal. 1984 Al-Sabri etal. 1993). These compounds include copper sulfate, copper pentachlorophenate, copper carbonate, copper-tartaric acid, Paris green (copper arsenite-acetate), copper oxide, copper chloride, copper acetyl acetonate, copper dimethyl dithiocar-bamate, copper ricinoleate, and copper rosinate (Cheng 1979). Also, many species of oyster enemies are controlled by copper sulfate dips. All tested species of marine gastropods, tunicates, echinoderms, and crabs that had been dipped for 5 seconds in a saturated solution of copper sulfate died if held in air for as little as a few seconds to 8 h mussels, however, were resistant (MacKenzie 1961). 

---