Brachyuran crabs (Decapoda, Brachyura) associated with the green sponge Amphimedon viridis (Demospongiae) from Itaguá Beach, south-eastern coast of Brazil

Abstract

This study provides information on the community structure of brachyuran crabs associated with the green sponge, Amphimedon viridis Duchassaing & Michelotti, 1864, from a beach on the southeastern coast of Brazil. Monthly collections from May 2002 through August 2003 were carried out on the rocky bottoms off Itaguá Beach (23°27 07 S 45°02 49 W). Crabs on the green sponge banks were hand-caught during snorkelling sessions, and 638 crabs belonging to 31 species, 19 genera, and 10 families were obtained. Biological parameters, including sponge volume, number of individuals, density, richness, diversity, evenness, and dominance changed considerably over time. Species recruitment and foraging habit are some of the factors that drive the richness, dominance, and diversity patterns of this community. The green sponge banks are important sites for recruitment, refuge, and feeding of many species of brachyurans. Therefore, they are also important for the conservation of this group on the south-eastern coast of Brazil. RESUMOEste estudo providencia informações da estrutura da comunidade de caranguejos braquiúros associados com a esponja verde Amphimedon viridis Duchassaing & Michelotti, 1864 da praia do Itaguá, na costa sudeste do Brasil. Foram realizadas coletas mensais de maio de 2002 a agosto de 2003 em fundos rochosos da Praia do Itaguá (23°27 07 S 45°02 49 W). Os caranguejos foram obtidos manualmente em bancos da esponja verde, durante sessões de mergulho livre. Foram obtidos 638 caranguejos, pertencentes a 31 espécies, 19 gêneros e 10 famílias. Os parâmetros biológicos, incluindo o volume da esponja, número de indivíduos, densidade, riqueza, diversidade, equidade, 4 ) e dominância mudaram consideravelmente ao longo do tempo. O recrutamento das espécies e o hábito alimentar são alguns dos fatores que controlam a riqueza, dominância e diversidade desta comunidade. Os bancos da esponja verde representam sítios importantes para o recrutamento, refúgio e alimentação de muitas espécies de Brachyura. Portanto, eles também são importantes para a conservação deste grupo na costa sudeste do Brasil.

Larval dispersal in three coral reef decapod species: Influence of larval duration on the metapopulation structure

“…Decapods may also use other living organisms as food and shelter. Sponge crab species carry upon their carapace sponge pieces or other organic materials to camouflage themselves from predators and to obtain their food by cutting some sponge fragments [ 39 ]. The emerald crabs seek refuge and protection among the tentacles of sea anemones [ 40 ].…”

Population dynamics of the mud crab Panopeus austrobesus Williams, 1983 (Brachyura: Panopeidae) associated with a mussel farm at the southeastern Brazilian coast

“…The difference in sizes recorded in this study, when compared with those reported by Negreiros-Fransozo and Fransozo (2003), seem to corroborate the results of Conde and Díaz (1992), which demonstrated that crabs in estuarine and riverine environments reach larger sizes when compared to crabs in hypersaline and marine habitats. Alves et al (2012a;2012b) also recorded a similar mean size for specimens of P. austrobesus from the Vitoria Archipelago (mean size = 5.4 ± 1.5 mm CW) and Itaguá Beach (mean size = 6.9 ± 4.6 mm CW), both of which are on the northeastern coast of São Paulo state, Brazil. It is probable that the negative association between the absolute abundance of P. austrobesus in the conditions of salinity and bottomwater temperature recorded in this investigation can be explained by the same reasons.…”

“…Second, the restricted size can also be an adaptation for exploiting the microhabitats in the farming nets. Alves et al (2012a;2012b) may corroborate this hypothesis, as the nets obtained crabs from rock crevices, which also offer small-sized refuges. Third, estuarine areas had a larger productivity than marine areas.…”

“…The recorded differences in the mean size and abundance of P. austrobesus populations from marine and estuarine habitats can be related to the following hypotheses: first, the marine population studied here is composed of juveniles and individuals that have just reached the adult phase, which recently initiated the colonization, since the nets were installed exclusively for this study. However, this hypothesis can be refuted, as the same mean sizes were reported by Alves et al (2012a;2012b) for marine habitats. Second, the restricted size can also be an adaptation for exploiting the microhabitats in the farming nets.…”

“…In spite of the importance of P. austrobesus as a primary consumer, especially in estuarine zones, information concerning the main features of its biology remains lacking. Except for studies related to taxonomy, composition, and geographical distribution (e.g., Melo, 1996;Vieira and Calazans, 2010;Marochi and Masunari, 2011;Alves et al, 2012a;2012b;Macedo et al, 2012), there is only a limited number of studies on the biology and ecology of P. austrobesus (see Montú et al, 1988;Negreiros-Fransozo and Fransozo, 2003). The aim of this investigation is to describe the population structure and dynamics of P. austrobesus associated with Population dynamics of Panopeus austrobesus Nauplius, 25: 2017017 P. perna mussel farms on the southeastern Brazilian coast and to compare its main characteristics to those of populations in their natural environments.…”