Bathymetric distribution of the shrimp Rimapenaeus constrictus (Stimpson, 1874) (Decapoda, Penaeidae) in two locations off the southeastern Brazilian coast

The distribution of benthic organisms is directly or indirectly associated with the physical and chemical properties of the water and sediment. This study analysed the spatial and temporal distribution of Rimapenaeus constrictus in unconsolidated sublittoral sediments of two areas off the northern coast of the state of Sao Paulo, Brazil. We also analysed the association of environmental factors with the occurrence of this species. Shrimp were collected monthly from July 2001 to June 2003, with a fishing boat equipped with two double-rig nets, in the regions of Ubatuba (UBA) and Caraguatatuba (CA). The collections were made during the day, along five transects with mean depths of 5, 10, 15, 20, 25, 30, and 35 m. We obtained a total of 5478 individuals, 3403 (UBA = 2025 and CA = 1378) during the first year, and 2075 (UBA = 875 and CA = 1200) during the second year. Significant differences in abundance were observed in relation to depth, season of the year, and also in the interaction between region and depth. Higher abundances occurred in fall and winter, independently of the sampling year. The largest numbers of shrimp were caught on the 20-m transect in UBA and the 25-m transect in CA. It is concluded that the distribution pattern of this species is closely related to environmental factors, and the temperature of the bottom water and the sediment texture were the most significant variables affecting the distribution.

Estimating abundance and spatial distribution patterns of the bubble crab Dotilla fenestrata (Crustacea : Brachyura)

The bubble crab Dotilla fenestrata forms very dense populations on the sand flats of the eastern coast of Inhaca Island, Mozambique, making it an interesting biological model to examine spatial distribution patterns and test the relative efficiency of common sampling methods. Due to its apparent ecological importance within the sandy intertidal community, understanding the factors ruling the dynamics of Dotilla populations is also a key issue. In this study, different techniques of estimating crab density are described, and the trends of spatial distribution of the different population categories are shown. The studied populations are arranged in discrete patches located at the well-drained crests of nearly parallel mega sand ripples. For a given sample size, there was an obvious gain in precision by using a stratified random sampling technique, considering discrete patches as strata, compared to the simple random design. Density average and variance differed considerably among patches since juveniles and ovigerous females were found clumped, with higher densities at the lower and upper shore levels, respectively. Burrow counting was found to be an adequate method for large-scale sampling, although consistently underestimating actual crab density by nearly half. Regression analyses suggested that crabs smaller than 2.9 mm carapace width tend to be undetected in visual burrow counts. A visual survey of sampling plots over several patches of a large Dotilla population showed that crab density varied in an interesting oscillating pattern, apparently following the topography of the sand flat. Patches extending to the lower shore contained higher densities than those mostly covering the higher shore. Within-patch density variability also pointed to the same trend, but the density increment towards the lowest shore level varied greatly among the patches compared.

Biological features of a puzzling symbiotic association between the hermit crab Dardanus insignis and the porcellanid crab Porcellana Sayana (Crustacea)

The symbiotic lifestyle is widespread among porcellanid crabs, which maintain ecological and co-evolutionary associations with annelid polychaetes, poriferans, cnidarians, echinoderms, gastropod. mollusks, and other crustaceans such as shrimps and hermit crabs, among others. We investigated the ecological association between the hermit crab Dardanus insignis and the porcellanid Porcellana sayana, in southeastern Brazil. Porcellanid crabs, hermit crabs, and available shells were collected monthly from July 2001 to June 2003, with a shrimp boat equipped with two double-rig trawl nets. The majority of P. sayana specimens were collected in shells occupied by D. insignis (96.6%); a few were found in empty shells (3.4%). The catch of both symbionts and hosts increased with increasing depth, with the highest occurrence at 35 m. The F. sayana crabs of various sizes could be found solitary or forming aggregations of up to 14 individuals per host, showing no sex or size segregation. In spite of the high diversity of shell species occupied by the hermit crabs and also available in the field, only a few of them were also utilized by P. sayana. The majority (93%) of shells utilized by P. sayana also hosted other symbiont species, constituting the basis of extensive symbiotic complexes. Thus, the ecological relationship between D. insignis and P. sayana may be classified as a non-obligate and non-specific symbiosis that may also involve other facultative organisms such as sea anemones. (C) 2008 Elsevier B.V. All rights reserved.

Dinâmica populacional do caranguejo-uçá, Ucides cordatus (Linnaeus, 1763) (CRUSTACEA, BRACHYURA, UCIDIDAE) no município de Porto do Mangue, litoral norte do estado do Rio Grande do Norte

Decapod crustaceans are one of the most important portions of megafaunal of coastal waters, playing a role as modifier of the environment and controlling populations of other organisms. Among the Decapoda, crab (brachyuran) constitutes the dominant macrofauna of mangroves. Among brachyuran is the mangrove crab (Ucides cordatus, Linnaeus, 1763), which represents the main component of the macrofauna of mangroves, particularly in Northern and Northeastern Brazil. In Brazil, its distribution is known from the state of Amapá to the north of Santa Catarina. This species is distinguished by its economic importance, being one of the main fishing resources in Brazil, generating a significant impact on their natural populations. This reduction would result in loss of value to the product, preventing its commercialization. Although it´s great ecological and economic importance, there are few articles about the biological aspects of U. cordatus, mainly in the state of Rio Grande do Norte. This work aimed to study the population dynamics of the mangrove crab, Ucides cordatus (Linnaeus, 1763), in Conchas estuary, Porto do Mangue, northern coast of Rio Grande do Norte. During the period November 2009 to October 2010 the crabs were collected monthly, obeying predetermined lunar periods (new moon or full moon) in a mangrove area in Porto do Mangue - RN. With the aid of a steel caliper (0.01 mm) and a precision balance (0.01 g) were measured biometric variables related to the animal's carapace, major propodus chela, width of abdomen (female), length of gonopodium ( males) and total weight. In addition, it was recorded, the gonads and molt stages, for males and females. In total, 476 crabs were collected, with 338 males and 138 females. Males were larger, heavier and in greater proportion than females. The reproductive period for the species in this location was limited during the months November to May, suggesting a change in current environmental legislation for the closure period. Synchrony was observed between the morphological and physiological maturity with females maturing earlier, possibly, a reproductive strategy adopted, compared to the low fishing pressure in the area. The molting period occurred in the dry season peaking in October. The analysis of growth, based on the parameters of von Bertalanffy was calculated using the nonlinear fit using modes (AJMOD). High growth rates for both males (L = 7.54 cm, k = 0.95, t0 =- 00:08; tmax = 4.84) and females (L = 6.50, k = 1 , 2, t0 =- 0008; tmax = 3.28) were found, contrasting with data from the literature, using other techniques. Males had higher asymptotic width size and longevity, but a lower growth constant when compared with females. The estimated age, for males and females, reaching the minimum capture size was 1.82 years and 1.63 years respectively. The size of physiological maturity, when individuals are able to reproduce, was estimated at 1.4 years and 1.05 years, for males and females, respectively. The recruitment period for this species is seasonal, with two peaks of occurrence, one in the rainy season and one in the dry season. This work represented the first effort on understanding the ecology of the mangrove crab, to the northern coast of Rio Grande do Norte. However, further studies on its biology should be undertaken, especially those related to growth, and recruitment, where observed that literature is more scarce

Ecological aspects of hermit crabs (Crustacea, Anomura, Paguroidea) off the northern coast of São Paulo State, Brazil

The occurrence of species of hermit crabs and their ecological distribution in soft bottoms off Ubatuba, São Paulo, Brazil were analyzed. To better understand the distribution of the species in relation to environmental factors, the similarity and species-diversity indexes were calculated. Paguroideans were sampled monthly from January through December 2000. The trawls were made with two otter-trawl nets at 13 different sites, at depths of 2-40 m. Water temperature, salinity, sediment texture, and organic matter content were measured. Gastropod shells occupied by hermit crabs were also assessed. A total of 1,238 specimens was collected, belonging to the families Diogenidae and Paguridae, comprising seven genera and thirteen species. The most abundant hermit crab species were Dardanus insignis (761 specimens) and Loxopagurus loxochelis (351 specimens). Phimochirus holthuisi is newly reported from the São Paulo coast. The highest diversity index was found for the shallower sites near rocky shores. The results of the grouping analysis for sites and species indicated three distinct groups for sites, and four groups for species. This suggests that the occurrence of these anomurans is associated with the environmental and biotic factors analyzed.

Bathymetric distribution of brachyuran crab (Crustacea, Decapoda) communities on coastal soft bottoms off southeastern Brazil

The communities of brachyuran crabs living on soft bottoms off Ubatuba in SE Brazil were studied with respect to their structure, bathymetric distribution, composition, diversity and indices of similarity. The data were analyzed using multivariate techniques of classification and ordination. Most of the individuals caught during summer were the swimming crab Portunas spinicarpus at the 35 m isobath, which contributed to the much-decreased diversity in this season and site. Multivariate analysis indicated that the species were distributed according to depth and also in relation to environmental gradients.

Ecology of a stream from upper Paraná River basin inhabited by Aspidoras fuscoguttatus Nijssen & Isbrüker, 1976 (Siluriformes, Callichthyidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Horizontal distribution of megalopae of Brachyura (Crustacea, Decapoda) in a South American tropical estuary

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento juvenil de duas espécies de siri (Crustacea, Decapoda, Portunidae) de importância econômica)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Distribuição ecológica dos Brachyura (Crustacea, Decapoa) do sublitoral rochoso de ilhas continentais do litoral norte do Estado de São Paulo

Pós-graduação em Ciências Biológicas (Zoologia) - IBB

Reproductive biology of Hepatus pudibundus (Crustacea: Brachyura), the most abundant crab on the southeastern Brazilian coast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morfologia do primeiro estágio juvenil de quatro espécies de caranguejos Leucosioidea (Crustacea: Decapoda: Brachyura), com proposta de padronização para as descrições dos estágios iniciais em Decapoda

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Admiralty Bay Benthos Diversity-A census of a complex polar ecosystem

A thorough census of Admiralty Bay benthic biodiversity was completed through the synthesis of data, acquired from more than 30 years of observations. Most of the available records arise from successive Polish and Brazilian Antarctic expeditions organized since 1977 and 1982, respectively, but also include new data from joint collecting efforts during the International Polar Year (2007-2009). Geological and hydrological characteristics of Admiralty Bay and a comprehensive species checklist with detailed data on the distribution and nature of the benthic communities are provided. Approximately 1300 species of benthic organisms (excluding bacteria, fungi and parasites) were recorded from the bay`s entire depth range (0-500 m). Generalized classifications and the descriptions of soft-bottom and hard-bottom invertebrate communities are presented. A time-series analysis showed seasonal and interannual changes in the shallow benthic communities, likely to be related to ice formation and ice melt within the bay. As one of the best studied regions in the maritime Antarctic Admiralty Bay represents a legacy site, where continued, systematically integrated data sampling can evaluate the effects of climate change on marine life. Both high species richness and high assemblage diversity of the Admiralty Bay shelf benthic community have been documented against the background of habitat heterogeneity. (C) 2010 Elsevier Ltd. All rights reserved.

Relative abundance and population biology of the non-indigenous crab Charybdis hellerii (Crustacea: Brachyura: Portunidae) in a southwestern Atlantic estuary-bay complex

Invasive species are potential threats to biodiversity, especially if they become established and outnumber native species. In this study, a population of the non-indigenous crab Charybdis hellerii was analyzed in an estuary-bay complex on the southeastern Brazilian coast, with respect to its abundance relative to sympatric native brachyuran species, as well as the size structure, sexual maturity, sex ratio, frequency of mutilation, reproductive period, and development of the reproductive system. Crabs were sampled monthly both in the intertidal zone of rocky shores and on sublittoral soft-bottom. Nine species were recorded on the rocky shores, where C. hellerii was the second most abundant species; only three individuals of C. hellerii were collected in the sublittoral samples. This population of C. hellerii showed a unimodal size structure composed mainly of mature individuals; males were larger than females, and the sex ratio was skewed toward males (3.1:1). About 46.9% of the individuals (75 of 160 crabs) had mutilated or regenerating appendages, more frequent in males (56.8%) than in females (28.2%), which may reflect both inter- and intraspecific agonistic interactions. A continuous reproductive pattern is suggested for this population, although ovigerous females occurred unevenly during the year, with 58.82% of them being collected in winter. There was evidence of multiple spawning, since the ovigerous females with an initial egg mass showed mature ovaries as well as seminal receptacles filled with sperm. C. hellerii is well established in the estuary-bay complex, but is concentrated in intertidal and shallow subtidal rocky shores, where it may compete with and replace other species such as the portunid Cronius ruber. This study also highlights the importance of systematic monitoring studies to evaluate the effects of the introduction of non-indigenous species on ecologically similar natives.

Reproductive biology of the ghost shrimp Lepidophthalmus bocourti (A. Milne-Edwards, 1870) (Decapoda: Axiidea: Callianassidae): A tropical species with a seasonal reproduction

Based on the hypothesis that reproduction is a continuous process in tropical habitats, we analysed reproductive periodicity and egg production in the callianassid ghost shrimp Lepidophthalmus bocourti, one of the most common species in mangrove systems along the Pacific coast of Central America. During one year (May 2008 to April 2009), individuals of L. bocourti (N = 499) were collected nearshore Gulf of Nicoya, Pacific coast of Costa Rica. Observations were made on presence or absence of incubated embryos, and gonad activity of females was analysed as gonadosomatic index (GSI). Our results revealed that L. bocourti has a marked seasonal breeding period, which contradicts previous reports regarding coastal marine decapods from the tropics. Ovigerous females were found only from June to August, while high GSI values were obtained from March to July. The increase of GSI and appearance of ovigerous females were associated with a concomitant decrease of salinity, but not with temperature. We assume that reproduction of L. bocourti is adapted to local changes of environmental conditions, and that a decrease in salinity during rainy season may serve as a triggering factor for ovarian development. Compared to other ghost shrimps, L. bocourti produced on average more (2002 +/- 1365) and smaller (0.87 +/- 0.109 mm) eggs, which seems to suggest that this species does not have an abbreviated larval development as reported for other species of genus. The deviation from the generalization of constant reproduction in the tropics for shallow water marine invertebrates and its probable cause are adequately discussed.