RESUMO

South Florida (USA) has a subtropical to tropical climate with an extensive and diverse coastline that supports the growth of benthic cyanobacterial mats (BCMs). These BCMs are widespread and potentially house numerous bioactive compounds; however, the extent of the cyanobacterial diversity within these mats remains largely unknown. To elucidate this diversity, BCMs from select locations in South Florida were sampled and isolated into unicyanobacterial cultures for morphological and molecular studies. Phylogenetic relationships of isolated taxa were assessed using the markers 16S rRNA and 16S-23S rRNA ITS by both maximum likelihood and Bayesian inference. We propose Affixifilum gen. nov. based on morphological characteristics and the 16S rRNA phylogeny. Two species are included: Affixifilum granulosum comb nov. (=Neolyngbya granulosa) found in Brazil and Florida (USA) and A. floridanum sp. nov. Several other features, including pair-wise distance of 16S rRNA and 16S-23S rRNA ITS, 16S-23S rRNA ITS secondary structure, morphology, and ecology, provide support for Affixifilum. We also propose the transfer of Lyngbya regalis to Neolyngbya as N. regalis comb. nov. and include the description of one novel species, N. biscaynensis sp. nov.

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RESUMO

Higher diversity and dominance at lower latitudes has been suggested for colonial species. We verified this pattern in species richness of ascidians, finding that higher colonial-to-solitary species ratios occur in the tropics and subtropics. At the latitudinal region with the highest ratio, in southeastern Brazil, we confirmed that colonial species dominate space on artificial plates in two independent studies of five fouling communities. We manipulated settlement plates to measure effects of predation and competition on growth and survivorship of colonial versus solitary ascidians. Eight species were subjected to a predation treatment, i.e. caged versus exposed to predators, and a competition treatment, i.e. leaving versus removing competitors, to assess main and interactive effects. Predation had a greater effect on growth and survivorship of colonial compared to solitary species, whereas competition did not show consistent patterns. We hypothesize that colonial ascidians dominate at this subtropical site despite being highly preyed upon because they regrow when partially consumed and can adjust in shape and space to grow into refuges. We contend that these means of avoiding mortality from predation can have large influences on diversification patterns of colonial species at low latitudes, where predation intensity is greater.

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The detailed study of arm ossicles, particularly the lateral arm plates, is providing valuable information in the elucidation of ophiuroid taxonomy. The present study describes in detail 16 species of brittle stars from Araçá Bay, Brazil. This information is used to construct the first interactive electronic key, providing a valuable resource for a broad range of researchers. Brittle stars families were divided into three groups based on their spatial distribution: i) infaunal species of intertidal and shallow subtidal belonging to Amphiuridae and Ophiactidae, ii) epizoic species belonging to Amphiuridae, Ophiactidae, and Ophiotrichidae and, iii) epifaunal species of the subtidal belonging to Ophiodermatidae and Hemieuryalidae. In the global context of recent revisions of ophiuroid taxonomy, the present work provides additional characters for use in future phylogenetic studies.

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RESUMO

Marine communities in tropical regions contain a great diversity of species that play key roles in ecological processes. The observed bycatch fauna in artisanal fishing for the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) in the southwest Atlantic exceeds the quantity of commercial shrimp captured. This bycatch has not been previously inventoried extensively in Brazil, particularly in the State of Santa Catarina, where small-scale shrimp fisheries is a traditional activity and dominates the local fishing economy. Six municipalities were sampled three times a month, from 1996 to 2011, yielding 216 species belonging to the bycatch (7 cnidarians, 22 mollusks, 42 crustaceans, 11 echinoderms, and 134 fishes). Bycatch management is a pressing aspect of shrimp fisheries. By inventorying the accidental bycatch, we provide a preliminary step towards defining intervention measures to reduce or make better use of this bycatch in seabob artisanal fisheries. Conservation of marine biodiversity is still inadequate in Brazil. We have attempted to identify additional threats to vulnerable and endangered species resulting from shrimp trawling.

Comunidades marinhas em regiões tropicais contêm uma grande diversidade de espécies que desempenham papéis-chave em processos ecológicos. A fauna acompanhante em pescas artesanais do camarão sete-barbas Xiphopenaeus kroyeri (Heller, 1862) no Atlântico Sudoeste excede a quantidade de camarões comerciais desta espécie capturados. Esta fauna acompanhante não foi catalogada de forma detalhada no Brasil, particularmente no Estado de Santa Catarina, onde a pescaria em pequena escala é uma atividade tradicional que domina a economia pesqueira local. Seis municípios foram amostrados três vezes por mês, de 1996 a 2011, capturando 216 espécies pertencentes è fauna acompanhante (7 cnidários, 22 moluscos, 42 crustáceos, 11 equinodermos e 134 peixes). O manejo da fauna acompanhante constitui um aspecto urgente nas pescarias de camarões. Ao listar a fauna acompanhante acidental, uma etapa preliminar é executada para a definição de medidas de intervenção, fazendo melhor uso desta fauna acompanhante na pesca artesanal de camarões. A conservação da biodiversidade marinha ainda é inadequada no Brasil. Apresentamos uma tentativa de identificar ameaças adicionais ès espécies vulneráveis e em risco de extinção como resultado das pescas de arrastro.