This study indicates the use of Phallusia nigra as a potential biomonitor of mercury contamination. In this way, Hg levels were measured in seawater and different parts of ascidians (tunic, hepatopancreas, and branchial basket) from eight different sites in the Todos os Santos Bay, Salvador-Bahia. The ascidians were lyophilized, weighed, and taken to the DMA-80 (direct mercury analyzer); the method accuracy was confirmed by analyzing the certified material DORM 4 muscle tissue and MEES-3 marine sediment with a confidence level of 95%. The results were evaluated through the Tukey’s test and it was possible to observe a higher concentration of Hg (82.00 312.7 ng g-1) in the branchial basket, followed by the hepatopancreas (69.67 130.7 ng g-1) and tunic (21.63-33.27 ng g-1). Thus, the branchial basket was the only tissue capable of identifying spatial differences in pollution between the points.

The lysianassoid species Eurythenes thurstoni Stoddart & Lowry, 2004 is recorded for the first time to the Southern Atlantic Ocean, with material collected from the South Mid-Atlantic Ridge during the MAR-ECO Project expeditions. The examined material presents some important variations when compared with the original description discussed in the text.

La especie lisianásida Eurythenes thurstoni Stoddart & Lowry, 2004 se registra por primera vez en el océano Atlántico sur, con el material colectado en la Cordillera Mesoatlántica Sur durante las expediciones del Proyecto MAR-ECO. El material examinado presenta algunas variaciones importantes en comparación con la descripción original, que se discute en el texto.

A new species of the family Melitidae Bousfield, 1973, Melita petronioi sp. nov., is described with material collected from Patos Lagoon, coast of the Brazilian state of Rio Grande do Sul, southern Brazil. The new species is the unique species of Melita Leach, 1814 in Brazilian waters with urosomites 1 and 2 lacking spines, but urosomite 2 bearing two sets of dorsal stout setae, and the uropod 3 with the outer ramus 2-articulate. It is the first Melita species recorded to the southern region of the country.