A B S T R A C TMarine organisms are affected by organotin compounds due to the cumulative, deleterious effects of these latter. The most evident and well known consequence of organotin contamination is imposex, a hormonal disruption that causes a superimposition of sexual male features in females of prosobranchia neogastropod molluscs such as Stramonita haemastoma floridana. Molluscs accumulate organotins mainly because of their poor ability to eliminate TBT and DBT from their tissues. The aim of this study was to analyze organotin uptake by ingestion experimentally, using uncontaminated subjects (S. haemastoma floridana) fed with organotin-contaminated oysters (Crassostrea rhizophorae). A total of 248 gastropods, distributed in 7 tanks with uncontaminated water and contaminated food, were used in this study, a control group being fed uncontaminated oysters. Every 15 days, the individuals of one of the tanks were examined for the presence of imposex. Development of imposex was measured using the VDSI, RPSI and RPLI indexes. The animals had already developed imposex within the first 15 days, all the indexes measured (RPLI, RPSI and VDSI) having increased significantly with duration of exposure, indicating that the animals were probably contaminated by the food and had accumulated the pollutant. New paths of imposex development were also observed. R E S U M OOrganismos marinhos são afetados por compostos organoestânicos que causam uma série de efeitos deletérios aos mesmos. O mais conhecido efeito da contaminação por organoestânicos é o imposex. Esse fenômeno consiste na masculinização de fêmeas de moluscos neogastrópodes tais como Stramonita haemastoma floridana. Esses compostos tendem a se acumular em moluscos devido a sua baixa capacidade de eliminá-los. Um total de 248 indivíduos de S. haemastoma floridana foram coletados de uma população livre qualquer indício de imposex. Esses animais foram mantidos em 7 aquários, com aproximadamente 30 indivíduos cada, 1 desses aquários foi considerado como controle e os animas do mesmo alimentados com ostras obtidas de locais onde não se verificou a ocorrência de imposex em neogastrópodes nativos. Os animais nos outros 6 aquários foram alimentados com ostras obtidas em local onde a incidência de imposex entre os gastrópodes nativos revelou-se muito alta. A cada 15 dias, por um período total de 90 dias, os animais de um dos tanques eram retirados e analisados quanto à presença de imposex. Os níveis de imposex foram quantificados através da % de imposex e dos índices: RPLI, RPSI e VDSI. Observou-se a indução de imposex em S. haemastoma floridana através da dieta a partir de Crassostrea rhizophora e um aumento significativo dos índices com o decorrer do tempo de exposição. Os animais do aquário controle foram analisados ao fim do experimento não revelando qualquer indício de imposex.

Imposex is the occurrence of male sexual features in female prosobranch mollusks exposed to organotin compounds. Since imposex has measurable characteristics, it has been used as a bioindication tool for the presence of this kind of pollutants. Thus, this work aimed to monitor organotin pollution over areas under the influence of ten main harbors of Northeastern Brazilian coast. Imposex intensity was measured using the indexes VDSI, RPSI, RPLI and the percentage of imposexed females. At least one sampling site in each studied harbor showed imposex, suggesting a widespread contamination by organotin compounds. However, the observed imposex levels are lower than those obtained by other monitoring works in highly industrialized regions of Europe and Asia, confirming that organotin contamination levels are higher in the most industrialized regions of the world. Approximately 39% of all sampling sites (32 sites) did not show imposexed females, suggesting that this feature does not occur naturally in Stramonita haemastoma and Stramonita rustica.

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