ABSTRACT We analyzed the spatio-temporal variations of the abundance, distribution and the population structure of Hexapanopeus paulensis Rathbun, 1930 from the southeastern Brazilian coast. Monthly samples were taken from January 1998 to December 1999 at Ubatumirim, Ubatuba and Mar Virado bays. A total of 1084 individuals were obtained, 76 specimens at Mar Virado, 322 at Ubatuba and 686 at Ubatumirim. It was possible to verify an association between the abundance of H. paulensis and bottom temperature (positive correlation), grain size of sediment and organic matter content (both negatively). This explains the higher number of individuals in the stations nearest to the continent (with higher temperature values and heterogeneous substrate). Juveniles were recorded throughout the study period, constituting 39.5% of the sampled population, which highlights the importance of the region (especially Ubatumirim Bay, due the highest abundance) for the establishment of the species. Only females occupied the largest size classes, which could mean differential mortality between the sexes or growth rate. Nevertheless, further studies should be accomplished to a better comprehension of such difference.

Abstract The variation in reproductive investment (RI) and the hypothesis of multiple spawning were evaluated in the redfinger rubble crab Eriphia gonagra (Fabricius, 1781). The gonads and embryos showed synchronous development, and fecundity and RI varied widely among females of the same size class. The mean RI value recorded was 11.31%, with no significant differences among the means for different size classes. The allometric analysis of fecundity indicated RI decrease while body size increase, but we suggested that this occurs due to size overestimation where the largest width of carapace was used as body size reference in these analyzes. In addition, we found an isometric relationship for “female weight vs. egg number”, and also for “female weight vs. egg weight”, indicating that RI increased proportionally with size of females. Relatively high frequencies both of smaller females with rudimentary gonads, and of larger females with developed gonads were observed. This indicates that larger females take place more frequently in the population reproductive output over time. This difference could not be observed by means of RI analyses of captured and fixed crabs, for which only one stage of gonad development and/or one spawning is usually recorded.

In this study, we estimated the size at onset of maturity (carapace width, CW50) and analyzed the relative growth of some body parts and the heterochely of the mud crab Hexapanopeus paulensis. A total of 800 crabs were collected, from January 1998 to December 1999, on the southeastern coast of Brazil. Each specimen was sexed and measured. CW50 was estimated to be 6.7 mm in males and 6.3 mm in females. Carapace length growth was negatively allometric in both sexes. Cheliped length and height was positively allometric for both males and females. Gonopod growth was isometric (b = 1) and negatively allometric (b < 1) in both juvenile and adult males, respectively. Abdomen relative growth was positively allometric (b > 1) for both juvenile and adult females. In males and females, the right cheliped was larger and higher than the left cheliped. Such heterochely may be related to the feeding habits of H. paulensis. Most xanthoid crabs, including the studied species, feed upon mollusks with dextral shells, which require complicated handling. In this sense, the heterochely in H. paulensis might facilitate the food manipulation.

En esto estudio se investigó la talla de primera madurez sexual (ancho del caparazón CW50), crecimiento relativo de varias estructuras corporales y la ocurrencia de heteroquelia en machos y hembras de Hexapanopeus paulensis. Se recolectó un total de 800 ejemplares, de enero 1998 diciembre 1999 en la región de Ubatuba, costa sureste de Brasil. Cada cangrejo recolectado fue sexado y medido. El CW50 ocurre a los 6,7 mm en machos y 6,3 mm en hembras. En machos juveniles y adultos, el crecimiento relativo (basado en el CW) del gonopodio fue isométrico (b = 1) y alométrico negativo (b < 1), respectivamente. El crecimiento relativo del abdomen fue alométrico positivo (b > 1) en hembras juveniles y adultas. El crecimiento relativo del ancho del caparazón fue alométrico negativo en los dos sexos. El alto y largo del quelípedo presentaron alometria positiva. El quelípedo derecho (largo y alto) fue más grande que el quelípedo izquierdo tanto en los machos como hembras. Consecuentemente, H. paulensis exhibe heteroquelia, lo que sugiere especialización de los quelípedos en relación a su hábito alimentario. Tanto H. paulensis como otros cangrejos xantoideos se alimentan de moluscos con conchas dextrógiras, y la destrucción de dichas conchas requiere de un manejo complejo de sus quelípedos. De este modo, los quelípedos heteroquélicos pueden facilitar la manipulación del alimento en el cangrejo H. paulensis.

Patterns of spatio-temporal distribution of Brachyura are determined by the interaction among life history traits, inter and intraspecific relationships, as well as by the variation of abiotic factors. This study aimed to characterize patterns of spatio-temporal distribution of Persephona lichtensteinii, Persephona mediterranea and Persephona punctata in two regions of the northern coast of São Paulo State, southeastern region of Brazil. Collections were done monthly from July 2001 to June 2003 in Caraguatatuba and Ubatuba, using a shrimp fishery boat equipped with double-rig nets. The patterns of species distribution were tested by means of redundancy analysis (RDA) and generalized linear mixed models (GLMM) in relation to the recorded environmental factors (BT: bottom temperature, BS: bottom salinity, OM: organic matter and granulometry (Phi)). The most influent environmental factor over the species distribution was the Phi, and the ascendant order of influence was P. lichtensteinii, P. punctata and P. mediterranea. The greater abundance of P. mediterranea showed a conservative pattern of distribution for the genus in the sampled region. The greater occurrence of P. punctata and P. lichtensteinii, in distinct transects than those occupied by P. mediterranea, seems to be a strategy to avoid competition among congeneric species, which is related to the substratum specificity.

Los patrones de distribución espacial-temporal de los Brachyura son determinados por la interacción entre aspectos de la historia de vida, relaciones inter e intraespecíficas, así como por las variaciones de los factores abióticos. El objetivo de este estudio fue caracterizar los patrones de distribución espacio-temporal de Persephona lichtensteinii, Persephona mediterranea y Persephona punctata en dos regiones de la costa norte del estado de São Paulo, Brasil. Se realizaron muestreos mensuales, de julio de 2001 a junio de 2003 en las regiones de Caraguatuba y Ubatuba, utilizando un barco camaronero equipado con redes de arrastre de tipo "double-rig". Los patrones de distribución de las especies fueron testeados por medio de una análisis de redundancia (RDA) y de modelos lineales generalizados mixtos (GLMM) por su asociación con los factores ambientales registrados (TF: temperatura de fondo, SF: salinidad de fondo, MO: materia orgánica y Phi). El factor ambiental más influyente sobre distribución de las especies fue el tamaño medio de grano (Phi). Siendo el grado de orden de influencia ascendente a partir de P. lichtensteinii, P. punctata y P. mediterranea. La mayor abundancia de P. mediterranea sobre P. punctata y P. lichtensteinii mostró un patrón de distribución conservativo de género para la región muestreada. Esta variación de abundancia puede estar relacionada con el límite de distribución de las especies. La mayor presencia de P. punctata y P. lichtensteinii en puntos distintos de los ocupados por P. mediterranea parece ser una estrategia para evitar la competencia entre especies congenéricas, relacionada con la especificidad del sustrato.

O desenvolvimento juvenil de Callinectes danae foi investigado a partir de megalopas obtidas em amostras de neuston em Ubatuba, São Paulo, Brasil. Os indivíduos foram criados emlaboratório sob temperatura constante (25 ± 1°C), água do mar filtrada proveniente do local de coleta (35‰) e fotoperíodo natural. Nauplii recém-eclodidos de Artemia sp. foram oferecidos diariamente como base de alimento e também ração de peixes ornamentais foi fornecida a juvenis a partir do 4° estágio. Foram obtidos 12 estágios da fase juvenil. As principais características morfológicas que permitiram o reconhecimento do primeiro estágio juvenil foram desenhadas e descritas. Todos os estágios subsequentes obtidos foram analisados e medidos, e as principais alterações em relação ao primeiro estágio foram registradas. O dimorfismo sexual torna-se evidente a partir do 4° estágio juvenil. Alguns apêndices e características morfológicas provaram ser de grande importância para identificação das espécies, incluindo o número de segmentos do flagelo antenal e o número de cerdas na maxila e no 1°, 2° e 3° maxilípedes. Estes, provavelmente, podem ser usados para futuras comparações e identificações de espécies.

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.

The spatial and seasonal distribution of different demographic groups of the swimming crab Callinectes ornatus was analyzed with respect to its population biology in three bays (Ubatumirim, Ubatuba, and Mar Virado) in southeastern Brazil. In each bay, monthly sampling was performed during two years along six transects, established at 5, 10, 15, and 20 m depth (parallel to the beach line), in a wave-sheltered area (7.5 m depth), and at an exposed site (10 m depth). Total abundance of crabs was similar among the bays. The presence of immature individuals, adult females, and breeding females was positively correlated with the bottom and surface temperatures, whereas adult males showed an opposite trend with respect to these factors. Immature and smaller individuals were most abundant along the sheltered and shallower transects. Males were more abundant along the shallower transects, and females at 15 and 20 m. This study revealed that different demographic groups occupy the habitat in different ways, according to local features. In general, southeastern Brazil offers a range of conditions that favor reproduction and consequently the maintenance and growth of the local population of C. ornatus, contributing to the relatively high abundance of the species in this coastal area.

Se analizó la distribución espacial y temporal de distintos grupos demográficos del cangrejo nadador Callinectes ornatus en cuanto a su biologia poblacional en tres bahias (Ubatumirim, Ubatuba y Mar Virado) en el sureste de Brasil. En cada bahia se realizaron muestreos mensuales durante dos años en seis transectos, establecidos a 5, 10, 15 y 20 m de profundidad (paralelo a la linea de costa), en una zona protegida del oleaje (7.5 m de profundidad) y en un sitio expuesto al oleaje (10 m de profundidad). La abundancia total de cangrejos fue similar entre bahias. Se observó una correlación positiva entre la presencia de individuos inmaduros, hembras adultas y hembras ovigeras con la temperatura del fondo y superficial, mientras que los machos adultos mostraron una tendencia opuesta con respecto a estos factores. La mayor abundancia de individuos inmaduros y pequeños fue detectada en los transectos protegidos y menos profundos. Los machos fueron más abundantes en los transectos menos profundos, y las hembras a 15 y 20 m de profundidad. Este estudio reveló que los diferentes grupos demográficos ocupan el hábitat de diferentes maneras, de acuerdo con las caracteristicas locales. En general, el sureste de Brasil ofrece diferentes condiciones que favorecen la reproducción y consecuentemente la continuidad y el crecimiento de la población local de C. ornatus, contribuyendo a la relativamente alta abundancia de la especie en esta zona costera.

Os objetivos deste estudo foram analisar a distribuição ecológica e a estrutura populacional de A. schmitti no litoral sudeste brasileiro. Os caranguejos foram coletados, mensalmente, de janeiro de 1998 a dezembro de 1999 nas enseadas: Ubatumirim (UBM), Ubatuba (UBA) e Mar Virado (MV), onde também foram obtidas amostras de água e sedimento para análise dos fatores ambientais. A maior abundância de A. schmitti foi verificada em UBM (224), seguida por UBA (154) e MV (23) e não apresentou associação com os fatores ambientais analisados. O motivo da baixa abundância desses caranguejos em MV pode ser a alta ação de ondas que movimenta o material biodetrítico acumulado no fundo e, frequentemente, remove pequenos caranguejos de seus abrigos entre fragmentos de conchas. Os indivíduos foram 269 machos e 132 fêmeas, das quais apenas 4 eram ovígeras. O recrutamento juvenil ocorreu o ano todo, sendo menos intenso na primavera. A maior abundância de indivíduos, bem como as fêmeas ovígeras, ocorreu em 1999, quando a entrada da Água Central do Atlântico Sul (ACAS) foi mais intensa do que no ano anterior. Esta influência ambiental pode ser o principal fator modulador para esta população.

This investigation analyzed the ecological distribution and population structure of A. schmitti on the southeastern coast of Brazil. Crabs were sampled monthly from January 1998 to December 1999 at the following bays: Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). Water and sediment samples were also collected from all sampling sites for an analysis of environmental factors. Acantholobus schmitti was most abundant at UBM (224), followed by UBA (154) and MV (23) but its abundance showed no association with the environmental factors analyzed. The low abundance of these crabs in MV may be due to the high wave action that moved biodetritic material accumulated on the bottom and frequently removed small crabs from their sheltered positions among the shell fragments. The individuals captured included 269 males and 132 females, of which only 4 specimens were brooding females. Juvenile recruitment occurred throughout the year, but was less intense in the spring. The major abundance of individuals as well as of ovigerous females occurred during 1999, when the entrance of the South Atlantic Central Waters (SACW) was stronger than in previous year. This environmental influence could be the main factor modulating this population.

In order to better understand the ecology of the different growth phases of the stone crab, Menippe nodifrons, and provide information for conservation of the natural stocks, this study describes the utilization of different biogenic substrates by this species in the intertidal zone. Sampling was carried out by hand at Ubatuba, State of Sao Paulo, Brazil. Crabs were captured among rocks or in association with three different biogenic substrates: Phragmatopoma lapidosa, Sargassum cymosum and Schizoporella unicornis. In the laboratory, the substrates were sorted and scanned for specimens of M. nodifrons, which were separated and measured at their maximum carapace width (CW), and classified as juvenile or adult specimens. Sex ratio and size distribution of crabs were analyzed for each of the substrate types. A total of 686 specimens of M. nodifrons were obtained during the sampling, ranging in size between 2.4 and 82.5 mm CW. Different mean sizes were recorded in the different substrates (P < 0.05). The high prevalence of juveniles in the samples suggests that these microhabitats are fundamental for the juvenile development of M. nodifrons, as they provide refuge, protection and probably food for juveniles.

Para comprender mejor la ecología de las diferentes fases de crecimiento de los cangrejos de piedra, Menippe nodifrons, y proporcionar información para la conservación de sus poblaciones naturales, se describe la utilización de los diferentes sustratos biogénicos, para esta especie en la zona intermareal. El muestreo se efectuó en Ubatuba, Estado de Sao Paulo, Brasil. Los cangrejos fueron capturados entre las rocas o en asociación con tres diferentes sustratos biogénicos: Phragmatopoma lapidosa, Sargassum cymosum y Schizoporella unicornis. En el laboratorio, los sustratos se clasificaron y analizaron en busca de especímenes de M. nodifrons, que fueron separados y medidos en el ancho máximo del caparazón (CW), y se clasificaron como juveniles o adultos. La proporción de sexos y la distribución de tamaño de los cangrejos se analizó para cada uno de los tipos de sustrato. Se obtuvo un total de 686 ejemplares de M. nodifrons, que variaron entre 2,4 y 82,5 mm CW. Se registraron tamaños medios significativamente diferentes en los distintos sustratos (P < 0,05). El alto número de juveniles en las muestras sugiere que estos microhábitats son fundamentales para el desarrollo juvenil de M. nodifrons, ya que proporcionan refugio, protección y, probablemente, alimentación para estos juveniles.

Este estudo investigou a importância dos fatores ambientais sobre os padrões de abundância dos decápodos na costa sudeste brasileira. Amostragens foram feitas mensalmente de janeiro-1998 a dezembro-1999 em Ubatumirim e Mar Virado, região de Ubatuba, usando um barco de pesca camaroneiro equipado com redes doublerig. Foram selecionadas seis áreas adjacentes aos costões rochosos. Amostras de água de fundo foram coletadas usando garrafa de Nansen, para mensurar a temperatura e salinidade. Amostras de sedimento foram obtidas utilizando pegador de Van Veen, para determinação da textura e conteúdo de matéria orgânica. A associação dos fatores ambientais com a abundância das espécies foi verificada através da Análise de Correspondência Canônica (α = 0,05). Quarenta e uma espécies de Decapoda foram utilizadas na análise multivariada. A análise indicou que a textura do sedimento (phi) e a temperatura foram os fatores mais fortemente correlacionados (p < 0,05) com a abundância espacial e temporal das espécies. Considerando a região de estudo como zona de transição faunística, incluindo espécies de origem tropical e subantártica, as espécies responderam diferentemente aos fatores ambientais, principalmente à temperatura. Possivelmente os decápodos ajustem sua distribuição de acordo com suas limitações fisiológicas intrínsecas, como resultado dos recursos disponíveis.

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.

OBJETIVO: A biologia populacional do camarão de água doce Macrobrachium jelskii foi investigada, com ênfase na distribuição de frequência em classes de tamanho, razão sexual, período reprodutivo e recrutamento juvenil. Além disso, a abundância dos indivíduos foi correlacionada com os fatores abióticos. MÉTODOS: Amostras foram coletadas mensalmente de julho de 2005 a junho de 2007, às margens do Rio Grande, região de Planura, estado de Minas Gerais, Brasil (20º 09' S e 48º 40' W), usando uma rede de arrasto (1.0 mm tamanho da malha e 2.0 × 0.5 m de largura). O equipamento foi arrastado por duas pessoas às margens da vegetação do rio por 100 metros de distância, percorridos por uma hora. Em laboratório, os espécimes foram identificados, mensurados e sexados. RESULTADOS: Um total de 2,789 espécimes foi analisado, no qual correspondem a 1,126 machos (549 jovens e 577 adultos) e 1,663 fêmeas (1,093 jovens, 423 adultos não ovígeras e 147 ovígeras). A razão sexual diferiu significativamente a favor de fêmeas de M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). A média de tamanho do comprimento da carapaça (CL) das fêmeas (6.32 ± 1.84 mm CL) foi estatisticamente maior do que dos machos (5.50 ± 1.07 mm CL) (p < 0.001). A distribuição de freqüência em classes de tamanho dos espécimes revela um padrão de distribuição unimodal e não normal para machos e fêmeas (W = 0.945; p < 0.01). Não foi observada relação entre a abundância de M. jelskii e as variáveis ambientais (p = 0.799). CONCLUSÃO: A presença de fêmeas ovígeras e jovens na população sugere um padrão de reprodução e recrutamento contínuos para M. jelskii na região de Planura.

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

A biologia populacional de Exhippolysmata oplophoroides (Holthuis, 1948) foi estudada na enseada de Ubatuba (23º26'S, 45º02'W), Ubatuba, São Paulo, Brasil, de setembro de 1995 até agosto de 1996. Cada amostragem compreendeu oito transectos (14000 m² cada), amostrados mensalmente com três repetições. Os espécimes foram classificados quanto à presença ou ausência de ovos nos apêndices abdominais. Os camarões espinhos ocorreram somente em seis transectos, sendo mais abundantes no transecto II, com a maior incidência no final da primavera e ao longo dos meses de verão. Indivíduos ovígeros e não ovígeros estiveram presentes o ano todo, numa proporção semelhante a 1:1. O transecto II é caracterizado por altos valores de salinidade e oxigênio, temperatura entre 26 e 29º C, baixo teor de matéria orgânica e sedimento composto por areia muito fina. Tais características biológicas e ambientais permitem o estabelecimento e a manutenção da população de E. oplophoroides na região de estudo.

The population biology of Exhippolysmata oplophoroides (Holthuis, 1948) was studied in Ubatuba Bay (23º26'S, 45º02'W), Ubatuba, São Paulo, Brazil, from September/1995 to August/1996. Each sampling comprised eight transects (14 000 m² each), sampled monthly with three repetitions. The specimens were classified with respect to the presence or absence of eggs in the abdominal appendages. Spine-shrimps occurred only on six transects, being most abundant on transect II, with the highest incidence in late spring and throughout the summer months. Ovigerous and non-ovigerous shrimps were present year-round, in an approximately similar proportion (1:1). Site II in Ubatuba Bay is characterized by high salinity and oxygen values, temperature between 26 and 29ºC, low organic matter content in the sediment, and a bottom composed of very fine sand; these environment and biological features allow the establishment and maintenance of the population of E. oplophoroides.