Population parameters and distribution of Arenaeus cribrarius (Crustacea, Portunoidea), in southeastern Brazilian coast / Parâmetros populacionais e distribuição de Arenaeus cribrarius (Crustacea, Portunoidea), no litoral sudeste brasileiro

To test the hypothesis of differential occupation of depths by demographic groups of A. cribrarius, their population structure, spatial-temporal distribution and sex ratio were studied, taking environmental factors into consideration. The animals were collected monthly during one year in Ubatuba, southeastern coast of Brazil, at nine different depths. There was no deviation from the pattern 1:1 sex ratio, and also no significant difference in size between the sexes. Reproductive activity was continuous, but more intense in the summer. It was possible to verify that there is differential occupation of space by demographic groups of A. cribrarius. Juveniles occupy shallower regions, which probably provide them with protection of predation. Adult males are more often collected in regions near these juveniles, probably in order to maximize the chances of finding primiparous females. Finally, adult females were more associated to deeper regions, where larval dispersal is facilitated by the influence of the movement of water mass.

Para testar a hipótese de ocupação diferencial de profundidade pelos grupos demográficos de A. cribrarius, a distribuição espaço-temporal, estrutura populacional e razão sexual foram estudadas, levando em consideração os fatores ambientais. Os animais foram coletados mensalmente durante um ano em Ubatuba, litoral sudeste brasileiro, em nove profundidades diferentes. Não houve desvio do padrão 1:1 para a razão sexual. Tampouco diferença significativa no tamanho entre os sexos. A atividade reprodutiva foi contínua, porém mais intensa no verão. Foi possível verificar que há ocupação diferencial do espaço pelos grupos demográficos de A. cribrarius. Juvenis ocuparam regiões mais rasas, que fornecem proteção contra a predação. Machos adultos foram mais frequentes em regiões próximas aos juvenis, o que, provavelmente, aumenta as chances de encontrar fêmeas primíparas. Finalmente, fêmeas adultas estiveram mais associadas às regiões mais profundas, onde a dispersão larval é facilitada pela influência do movimento das massas de água.

Population parameters and distribution of Arenaeus cribrarius (Crustacea, Portunoidea), in southeastern Brazilian coast / Parâmetros populacionais e distribuição de Arenaeus cribrarius (Crustacea, Portunoidea), no litoral sudeste brasileiro

To test the hypothesis of differential occupation of depths by demographic groups of A. cribrarius, their population structure, spatial-temporal distribution and sex ratio were studied, taking environmental factors into consideration. The animals were collected monthly during one year in Ubatuba, southeastern coast of Brazil, at nine different depths. There was no deviation from the pattern 1:1 sex ratio, and also no significant difference in size between the sexes. Reproductive activity was continuous, but more intense in the summer. It was possible to verify that there is differential occupation of space by demographic groups of A. cribrarius. Juveniles occupy shallower regions, which probably provide them with protection of predation. Adult males are more often collected in regions near these juveniles, probably in order to maximize the chances of finding primiparous females. Finally, adult females were more associated to deeper regions, where larval dispersal is facilitated by the influence of the movement of water mass.(AU)

Para testar a hipótese de ocupação diferencial de profundidade pelos grupos demográficos de A. cribrarius, a distribuição espaço-temporal, estrutura populacional e razão sexual foram estudadas, levando em consideração os fatores ambientais. Os animais foram coletados mensalmente durante um ano em Ubatuba, litoral sudeste brasileiro, em nove profundidades diferentes. Não houve desvio do padrão 1:1 para a razão sexual. Tampouco diferença significativa no tamanho entre os sexos. A atividade reprodutiva foi contínua, porém mais intensa no verão. Foi possível verificar que há ocupação diferencial do espaço pelos grupos demográficos de A. cribrarius. Juvenis ocuparam regiões mais rasas, que fornecem proteção contra a predação. Machos adultos foram mais frequentes em regiões próximas aos juvenis, o que, provavelmente, aumenta as chances de encontrar fêmeas primíparas. Finalmente, fêmeas adultas estiveram mais associadas às regiões mais profundas, onde a dispersão larval é facilitada pela influência do movimento das massas de água.(AU)

Decapod crustaceans captured along with the sea-bob shrimp fisheries on non-consolidated sublitoral from Northern coast of São Paulo, Brazil / Crustáceos decápodes capturados na pesca do camarão-sete-barbas no sublitoral não consolidado do litoral norte do estado de São Paulo, Brasil

Studies on natural communities are essential for a correct interpretation of the disturbing events, either natural or anthropic. Many species which are not the target of fisheries are captured in the shrimp fishery. Such fact is attributed to the non-selective fishery device used (double-rig trawl), that destabilizes the benthic community. This study provides a landscape on the crustacean decapods community, captured more than 20 years ago by means the shrimp fishery of the X. kroyeri (sea-bob shrimp) at the northern littoral of São Paulo. Samples were collected monthly from November/1988 to October/1989 at the Fortaleza bay. A total of 20377 specimens of 44 species were obtained. The most abundant was X. kroyeri with 13206 individuals. The higher values of diversity index (Shannon-Wiener) were obtained in the sites II and V, which are fishery natural exclusion areas. Our results show that the decapod diversity can be affected in those areas in which the fishery activity is more intense.

Estudos sobre as comunidades são essenciais para uma interpretação adequada dos eventos perturbadores, sejam eles antrópicos ou não. Na pesca camaroneira, muitos crustáceos sem valor econômico são capturados. Tal fato é atribuído ao uso de um apetrecho de pesca não seletivo (rede double-rig), tornando a pesca uma atividade desestabilizadora das comunidades bentônicas. Este estudo apresenta um panorama sobre as espécies de crustáceos decápodes capturados na pesca de Xiphopenaeus kroyeri (camarão-sete-barbas). As coletas foram realizadas no período de novembro/1988 a outubro/1989 na Enseada da Fortaleza, litoral norte paulista. Foram coletados 20.377 indivíduos pertencentes a 44 espécies, das quais a mais abundante foi X. kroyeri com 13.206 indivíduos. Os maiores valores de índice de diversidade (Shannon-Wiener) foram observados nos pontos amostrais II e V, que correspondem a áreas de exclusão natural de pesca. Este estudo aponta que, em locais onde a atividade pesqueira é mais intensa, a biodiversidade pode ser afetada.

Decapod crustaceans captured along with the sea-bob shrimp fisheries on non-consolidated sublitoral from Northern coast of São Paulo, Brazil / Crustáceos decápodes capturados na pesca do camarão-sete-barbas no sublitoral não consolidado do litoral norte do estado de São Paulo, Brasil

Studies on natural communities are essential for a correct interpretation of the disturbing events, either natural or anthropic. Many species which are not the target of fisheries are captured in the shrimp fishery. Such fact is attributed to the non-selective fishery device used (double-rig trawl), that destabilizes the benthic community. This study provides a landscape on the crustacean decapods community, captured more than 20 years ago by means the shrimp fishery of the X. kroyeri (sea-bob shrimp) at the northern littoral of São Paulo. Samples were collected monthly from November/1988 to October/1989 at the Fortaleza bay. A total of 20377 specimens of 44 species were obtained. The most abundant was X. kroyeri with 13206 individuals. The higher values of diversity index (Shannon-Wiener) were obtained in the sites II and V, which are fishery natural exclusion areas. Our results show that the decapod diversity can be affected in those areas in which the fishery activity is more intense.(AU)

Estudos sobre as comunidades são essenciais para uma interpretação adequada dos eventos perturbadores, sejam eles antrópicos ou não. Na pesca camaroneira, muitos crustáceos sem valor econômico são capturados. Tal fato é atribuído ao uso de um apetrecho de pesca não seletivo (rede double-rig), tornando a pesca uma atividade desestabilizadora das comunidades bentônicas. Este estudo apresenta um panorama sobre as espécies de crustáceos decápodes capturados na pesca de Xiphopenaeus kroyeri (camarão-sete-barbas). As coletas foram realizadas no período de novembro/1988 a outubro/1989 na Enseada da Fortaleza, litoral norte paulista. Foram coletados 20.377 indivíduos pertencentes a 44 espécies, das quais a mais abundante foi X. kroyeri com 13.206 indivíduos. Os maiores valores de índice de diversidade (Shannon-Wiener) foram observados nos pontos amostrais II e V, que correspondem a áreas de exclusão natural de pesca. Este estudo aponta que, em locais onde a atividade pesqueira é mais intensa, a biodiversidade pode ser afetada.(AU)

Juvenile development of Callinectes danae Smith, 1869 (Crustacea, Decapoda, Brachyura, Portunidae) under laboratory conditions.

The juvenile development of Callinectes danae was investigated from megalopae obtained in neuston samples at Ubatuba, São Paulo, Brazil. The individuals were raised in the laboratory under constant temperature (25 ± 1°C), filtered sea water from the collection location (35‰), and natural photoperiod. Newly hatched Artemia sp. nauplii were offered as food on a daily basis and ornamental-fish food was also provided for the juveniles from the 4th stage on. Twelve stages of the juvenile phase were obtained. The main morphological features that allowed recognition of the first juvenile stage were drawn and described. All the subsequent stages obtained were examined and measured, and the main changes in relation to the first stage were recorded. Sexual dimorphism becomes apparent from the fourth juvenile stage onwards. Some appendages and morphological features proved to be of great importance in the identification of species, including the number of segments of the antennal flagellum and the number of setae on the maxilla and on the 1st, 2nd and 3rd maxillipeds. These can probably be used for future comparisons and species identifications.

Effect of environmental factors on the abundance of decapod crustaceans from soft bottoms off southeastern Brazil.

This study investigated the importance of variations in environmental factors affecting the abundance patterns of decapods on the southeastern Brazilian coast. Sampling was carried out monthly from January 1998 through December 1999 in Ubatumirim and Mar Virado, Ubatuba region, using a commercial shrimp fishing boat equipped with double-rig nets. Six areas adjacent to rocky shores were chosen. Bottom-water samples were collected using a Nansen bottle, to measure the temperature and salinity. Sediment samples were also obtained by means of a Van Veen grab, for determination of texture and organic-matter content. The association of environmental factors with species abundance was evaluated by Canonical Correspondence Analysis (α = 0.05). Forty-one species of Decapoda were used in the multivariate analysis. The analysis indicated that sediment texture (phi) and bottom temperature were the main factors correlated (p < 0.05) with the spatial and temporal abundance of the species. Considering the study region as faunal transition zone, including a mixture of species of both tropical and subantarctic origin, the species responded differently to environmental factors, mainly temperature. It is conceivable that the decapods adjust their distribution according to their intrinsic physiological limitations, possibly as a result of the available resources.