Molecular evidence of two cryptic species of Stramonita (Mollusca, Muricidae) in the southeastern Atlantic coast of Brazil.

Snails of the genus Stramonita are commonly found in the rocky intertidal habitat of the western Atlantic Ocean coast. They belong to a monophyletic taxon that occurs along the tropical and warm-temperate Atlantic and eastern Pacific rocky shores. This genus comprises different valid species and members of the S. haemastoma complex. In the present study, samples of Stramonita were collected from three different regions of southeastern Brazil. Partial sequences of two mitochondrial genes, COI and 16S rRNA, were used to compare nucleotides sequences between Stramonita specimens. Levels of nucleotide divergence greater than 2% across the three sampled regions were used for differentiation at the species level. One of the identified species was S. brasiliensis, which has recently been described by molecular analysis; the other species may represent S. haemastoma, not yet described in the southeastern Brazilian coast.

The Path towards Endangered Species: Prehistoric Fisheries in Southeastern Brazil.

Brazilian shellmounds are archaeological sites with a high concentration of marine faunal remains. There are more than 2000 sites along the coast of Brazil that range in age from 8,720 to 985 cal BP. Here, we studied the ichthyoarchaeological remains (i.e., cranial/postcranial bones, otoliths, and teeth, among others) at 13 shellmounds on the southern coast of the state of Rio de Janeiro, which are located in coastal landscapes, including a sandy plain with coastal lagoons, rocky islands, islets and rocky bays. We identified patterns of similarity between shellmounds based on fish diversity, the ages of the assemblages, littoral geomorphology and prehistoric fisheries. Our new radiocarbon dating, based on otolith samples, was used for fishery characterization over time. A taxonomical study of the ichthyoarchaeological remains includes a diversity of 97 marine species, representing 37% of all modern species (i.e., 265 spp.) that have been documented along the coast of Rio de Janeiro state. This high fish diversity recovered from the shellmounds is clear evidence of well-developed prehistoric fishery activity that targeted sharks, rays and finfishes in a productive area influenced by coastal marine upwelling. The presence of adult and neonate shark, especially oceanic species, is here interpreted as evidence of prehistoric fisheries capacity for exploitation and possibly overexploitation in nursery areas. Various tools and strategies were used to capture finfish in seasonal fisheries, over rocky reef bottoms and in sandy littoral environments. Massive catches of whitemouth croaker, main target dermersal species of South Atlantic coast, show evidence of a reduction in body size of approximately 28% compared with modern fisheries. Fishery activity involving vulnerable species, especially in nursery areas, could mark the beginning of fish depletion along the southeastern Brazilian coast and the collapse of natural fish populations.

Maintenance of filtering molluscs in aquaria for sub-chronic studies

This work determined the best survival conditions for the clam Mytella guyanensis and the mussel Perna perna in the estuary and sea aquaria respectively over at least 12 days, which could enable their use in the ecotoxicological studies. The aquaria were set up with the appropriate water and sedimen, and allowed to establish for a minimum of one month before adding the organisms. The best survival conditions for M. guyanensis required more time for the aquarium stabilization, addition of inocula and more frequent water changes than for P. perna. The organisms' lipid contents increased and their condition index was maintained indicating the good conditions of the aquaria, hence, their possible use in the sub-chronic studies.

Estudos sobre a dinâmica de contaminação de organismos marinhos devem ser feitos sob condições controladas pelo tempo necessário para que os organismos possam responder à presença do agente contaminante. No entanto, a manutenção de organismos em aquários por determinado período pode ser difícil porque todas as outras variáveis do ambiente precisam ser próximas às condições naturais. Este trabalho determinou as melhores condições de sobrevivência do marisco Mytella guyanensis e do mexilhão Perna perna, respectivamente em aquários de estuário e de mar, por período de até 12 dias. Os aquários foram montados com água e sedimento de estuário ou de mar e estabilizados por, no mínimo, um mês antes da colocação dos respectivos organismos. As melhores condições de sobrevivência de M. guyanensis requisitaram mais tempo de estabilização do aquário, adição de inóculos e trocas de água mais freqüentes do que para os P. perna. Os conteúdos de lipídios aumentaram com o tempo e o índice de condição dos organismos foi mantido, indicando as boas condições dos aquários e, conseqüentemente, a possibilidade de uso em pesquisas ecotoxicológicas.

Dimorfismo sexual secundário no Caçäo Scyliorhinus haeckelli Ribeiro, 1907 (Elasmobranchii, Scyliorhinidae) / Secondary sex dimorphism in the shark Scyliorhinus haeckelli Ribeiro, 1907 (Elasmobranchii, Scyliorhinidae)

The secondary sexual dimorfism in the shark Scyliorhinus haeckelii Ribeiro, 1907 is herein presented and analysed based on the morphology og tyhe dentition, jaw and snout shape, dermal denticles and the colour of 21 specimens of the species