Benthic community structure and diversity have been investigated to assess stress conditions of Todos os Santos Bay, Bahia, Brazil, as a possible result of the extraction, transportation and re®ning of petroleum, activities carried out in this area for more than 40 years. Samples were collected over two years, at four stations under the direct in¯uence of stress-causing activities and at a control station. Benthic indices were calculated for all intertidal communities. The density, relative abundance, frequency of occurrence, diversity, similarity and occurrence of preferential species were recorded. Linear correlation indices were calculated to establish comparisons between ecological parameters of the studied communities and concentrations of heavy metals, hydrocarbons, petroleum pollution indicators and sediment mud percentages. The polychaete worms were the dominant group Ð up to 92% dominance in the community within the in¯uence of re®nery activities. Diversity indices indicated signi®cant stress related spatial gradients tied to petroleum. The re®nery sample station showed notable differences in its biodiversity ®gures compared to the other stations. Quantitative benthic indices showed negative correlations between the presence of cadmium, hydrocarbons, n-alkanes and the unresolved complex mixture in the intertidal zone marine sediments.

A anatomia funcional de Lucina pectinata (Gmelin, 1791) foi estudada neste trabalho tendo sido dada atenção especial à formação do tubo inalante anterior, ao funcionamento do pé, manto, brânquias do manto, ctenídios, palpos labiais e estômago. Observações do comportamento do bivalve e o funcionamento destes órgãos permitiram verificar as adaptações relacionadas à vida em ambientes lodosos de enseadas sem arrebentação, onde existe pequena quantidade de alimento e pouco oxigênio em dissolução. Foiam analisadas a motilidade e atuação do pé, o tamanho dos palpos, ciliação do manto, do músculo adutor anterior, dos ctenídios e a estrutura e funcionamento do estomago. Os sifões são do tipo A (Yonge, 1948), os ctenídios pertencem a um novo tipo: G1, a relação entre os palpos e ctenídios é da categoria m (Stasek, 1963) e o estômago do tipo IV (Purchon, 1958).

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