Ricardo S. Rosa

Use of natural marks on population estimates of the nurse shark, Ginglymostoma cirratum, at Atol das Rocas Biological Reserve, Brazil

We assessed information on the population structure of the nurse shark, Ginglymostoma cirratum, at Atol das Rocas, northeastern Brazil, through underwater observations. Based on photographic records of natural distinctive marks for individual recognition, we used probabilistic estimators (Petersen–Bailey and Jolly–Seber) to assess population size. We found that 46% of the sharks (194 individuals) had distinctive marks. The population size was estimated in 368 individuals, using the Petersen–Bailey estimator, and 339 individuals using the Jolly–Seber estimator.

Peixes recifais da costa da Paraíba, Brasil

The coral reef is an ecossystem which evokes great interest, for its beaury, species diversity and fisheries potential. The coast of Paraiba State, northeast Brazil, possesses several natural reefs and shipwrecks which are inhabited by a rich fish fauna. In order to survey the reef fish fauna of Paraiba State, a total of 118 dives, utilizing SCUBA diving techniques, were carriedoutin 27samplingpoints (depths: 0,5-66m), from February/1995 to May/1996. Specimens were collected whenever underwater identification was precluded. A total of 157 known species belonging to 59 families were found. Four unidentified species, one dasyatid, one haemulid, one scarid, and one labrid were recorded. Haemulidae was the most representative family in number of individuais, whereas Carangidae was the most speciose family. This paper is part of a broader study of the northeast Brazilian reef fishes.

Plesiotrygon iwamae, a New Genus and Species of Neotropical Freshwater Stingray (Chondrichthyes: Potamotrygonidae)

A new genus and species of neotropical freshwater stingray are described from the upper and mid-Amazon drainage, in Ecuador and Brazil (Rio Napo and Rio Solimbes). The new taxa are characterized by a long filiform tail, reduced eyes, and low number of pectoral-fin radials. The new genus, presently monotypic, is hypothesized to be primitive relative to the other genera of the family (Potamotrygon and Paratrygon). A key to the genera of Potamotrygonidae is presented.

Diversidade da ictiofauna de poças de maré da praia do Cabo Branco, João Pessoa, Paraíba, Brasil

A survey of the tidal pool fish community was carried out between february/1987 and january/1988, at Cabo Branco Beach, Joao Pessoa, Paraiba, Brazil. Specimens were collected monthly at low tide, using rotenone. A total of 3143 specimens was obtained. The most speciose families were Ophichthidae (14% of the total number of species), Mugilidae (11%) and Muraenidae (9%), and the most representative ones in number of individuais were Gobiidae (48%), Pomacentridae (13%) and Labrisomidae (10%). The main resident species were Bathygobius soporator (Valenciennes, 1837) and Abudefduf saxalilis (Linnaeus, 1758). The presence of a large number of juveniles in the pools indicated the importance of the studied sites as nursery areas for several fish species.

Fish assemblage of the Mamanguape Environmental Protection Area, NE Brazil: abundance, composition and microhabitat availability along the mangrove-reef gradient

Reefs, mangroves and seagrass biotopes often occur in close association, forming a complex and highly productive ecosystem that provide significant ecologic and economic goods and services. Different anthropogenic disturbances are increasingly affecting these tropical coastal habitats leading to growing conservation concern. In this field-based study, we used a visual census technique (belt transects 50 m x 2 m) to investigate the interactions between fishes and microhabitats at the Mamanguape Mangrove-Reef system, NE Brazil. Overall, 144 belt transects were performed from October 2007 to September 2008 to assess the structure of the fish assemblage. Fish trophic groups and life stage (juveniles and adults) were recorded according to literature, the percent cover of the substrate was estimated using the point contact method. Our results revealed that fish composition gradually changed from the Estuarine to the Reef zone, and that fish assemblage was strongly related to the microhabitat availability, as suggested by the predominance of carnivores at the Estuarine zone and presence of herbivores at the Reef zone. Fish abundance and diversity were higher in the Reef zone and estuary margins, highlighting the importance of structural complexity. A pattern of nursery area utilization, with larger specimens at the Transition and Reef Zone and smaller individuals at the Estuarine zone, was recorded for Abudefduf saxatilis, Anisotremus surinamensis, Lutjanus alexandrei, and Lutjanus jocu. Our findings clearly suggests ecosystem connectivity between mangrove, seagrass and reef biotopes, and highlighted the importance of Mamanguape Mangrove-Reef System as a priority area for conservation and research, whose habitat mosaics should be further studied and protected.

Potamotrygon boesemani (Chondrichthyes: Myliobatiformes: Potamotrygonidae), a new species of Neotropical freshwater stingray from Surinam

Potamotrygon boesemani, new species, is described from the Corantijn river drainage in Surinam. The species has a diagnostic dorsal color pattern formed by deep orange to red ocellated spots of irregular form, encircled by relatively broad black rings. Potamotrygon boesemani is distinguished from other ocellated congeners (P. motoro, P. henlei and P. leopoldi) by the more intensely colored ocelli, which are usually yellow in the latter species. From P. motoro it is also distinguished by the darker dorsal background coloration, by the broader black contour of the dorsal ocelli, and by the irregular form of the ocelli as compared to the more rounded shape in the latter species. From P. henlei and P. leopoldi, it is distinguished by the lack of ocelli on tail. From the tentatively identified specimen of P. ocellata, which also has dark orange ocelli, the irregular contour of the ocelli in the new species is also distinctive. The teeth are relatively smaller and in greater number than in P. motoro and P. ocellata, with up to 45 rows in the upper jaw.

Relação preliminar das espécies de peixes (Pisces, Elasmobranchii, Actinopterygii) ameaçadas no Brasil

The Brazilian fish fauna is still poorly known with respect to its diversity and conservation status, particularly of freshwater species. Human activities and population growth are rapidly impacting this fauna to an unchecked extent, so that many fish species are presently threatened. Also, some areas have been so critically altered that their fish fauna can no longer be properly inventoried. There is an urgent need to evaluate the conservation status of Brazilian fish species, since none are presently listed as endangered by federal legislation. Based on a literature search and a survey directed to the Neotropical ichthyologists, we present an unofficial list including a total of 78 threatened fish species (12 elasmobranchs and 66 actinopterygians). Of these, sixteen actinopterygian species are listed as endangered, three elasmobranchs and nine actinopterygians as vulnerable, and seven actinopterygians as rare; 40 species either have indeterminate status or are data deficient to yield an adequate assessment, and three species are listed as extinct or possibly extinct.

Systematic revision of the South American species of Pinguipedidae (teleostei, trachinoidei)

Five genera of marine fishes are recognized in the family Pinguipedidae: Pinguipes, Prolatilus, Pseudopercis, Paraperci and Kochichlhys, the first three being endemic to South America. The following South American pinguipedid species are considered valid: Pinguipes brasilianus, Pinguipes chilensis, Prolatilus jugularis, Pseudopercis numida, Pseudopercis semifasciata and Parapercis dockinski. Lecto-types are designated for Pinguipes brasilianus, Pinguipes chilensis and Prolatilus jugularis.

Systematic Revision of the Genus Cnesterodon (Cyprinodontiformes: Poeciliidae) with the Description of Two New Species from Brazil

The South American genus Cnesterodon is rediagnosed, and an account of its osteology presented. Four species are recognized. Cnesterodon decemmaculatus (Jenyns) from the lower Parana River system and adjacent basins and C. carnegiei Haseman from the upper Parana River system are redescribed. Cnesterodon brevirostratus n. sp. is described from the upper Uruguay and Jacui river drainages in Santa Catarina and Rio Grande do Sul states, southern Brazil; it is diagnosed by a relatively short snout. Cnesterodon septentrionalis n. sp. is described from the Rio Araguaia drainages, in Mato Grosso state, central Brazil; it is diagnosed by the low number of caudal-fin rays. Discovery of the last species constitutes the first record of the genus outside the Parana River system and the coastal drainage basins of southeastern Brazil and adjacent Uruguay and Argentina. A key to the species of Cnesterodon is provided. O genero sul-americano Cnesterodon e rediagnosticado e uma descricao de sua osteologia e apresentada. Quatro especies sao reconhecidas, duas delas aqui descritas como novas. Cnesterodon decemmaculatus (Jenyns), do sistema do baixo Rio Parana e bacias adjacentes, e C. carnegiei Haseman, do sistema do alto Rio Parana, sao redescritas. Cnesterodon brevirostratus sp. n. e descrita das drenagens do alto Rio Uruguai e Rio Jacui, nos estados de Santa Catarina e Rio Grande do Sul, no sul do Brasil; e diagnosticada pelo focinho curto. Cnesterodon septentrionalis sp. n. e descrita da drenagem do Rio Araguaia, Estado de Mato Grosso, no Brasil central; e diagnosticada pelo reduzido nuimero de raios da nadadeira caudal. A descoberta desta ultima especie constitui o primeiro registro do genero fora do sistema do baixo Rio Parana e bacias costeiras do sul do Brasil, Uruguai e Argentina. Uma chave para as especies de Cnesterodon e apresentada.

Population size and survivorship for juvenile lemon sharks (Negaprion brevirostris) on their nursery grounds at a marine protected area in Brazil

Os tubaroes enfrentam muitos obstaculos para sobreviver nos primeiros anos de vida e muitas especies ocupam areas de bercario. Embora estimativas de sobrevivencia, particularmente para jovens, sejam essenciais para acessar, monitorar e manejar efetivamente populacoes animais, existem poucos calculos destas estimativas para populacoes de tubaroes e poucas estimativas baseadas em metodos diretos para estes animais em suas areas de bercario. Metodos de marcacao e recaptura foram utilizados no presente estudo para estimar o tamanho populacional e a sobrevivencia de jovens tubaroes-limao (Negaprion brevirostris) em uma area de bercario na Reserva Biologica do Atol das Rocas, Brasil. Os individuos foram amostrados entre 1999 e 2003 e as estimativas de tamanho populacional variaram entre 12 a 100 individuos jovens e a taxa de sobrevivencia entre 24 e 54%, com media de 44,6% durante o periodo de amostragem mais robusto. A populacao destes tubaroes jovens diminuiu ao longo de nosso estudo, ainda que as taxas de sobrevivencia tenham aumentado durante o mesmo periodo. Mesmo um nivel moderado de pesca e a remocao de femeas maduras em areas adjacentes podem afetar dramaticamente pequenas populacoes de tubaroes num bercario pequeno e isolado como o Atol das Rocas. As taxas de sobrevivencia e tamanho populacional relativamente mais baixos em Rocas podem ser resultado das diferencas nas caracteristicas fisicas deste bercario, comparadas a outros utilizados pela especie no Atlântico norte-ocidental. Tais parâmetros comparativamente mais baixos no Atol das Rocas sugerem a fragilidade da populacao jovem de tubaroes-limao neste bercario.