Distribuição, abundância e biologia populacional da Família Porcellanidae na Baía de Sepetiba/RJ, Brasil

Abstract

Crabs of the Porcellanidae Family are considered one of the most common and abundant groups of crustaceans in intertidal rocky habitats of the region. This study aimed to examine distribution and abundance patterns of intertidal porcelain’s fauna of the Sepetiba Bay, as well as studying various aspects of population and reproductive biology of P. armatus on two islands and a mainland. The capture of animals began in July/2004, on the island of Marambaia, and ended up in February/2007 in Prainha. In all 7 points were selected for study, distributed among internal (Marambaia Island, Ibicuí and Junqueira Beach), middle (Lopes’ Lage and Prainha – Itacuruçá Island) and outside of the Bay (Itacuruçá and Guaratiba). Manual samples were made in consolidated substrates in intertidal zone, is capturing the animals under stones, logs, from algae, shells, oysters, sponges, bryozoans and burrow into rock cracks. Different methodological strategies were made among the collection points. In the laboratory the animals were separated by sex and development stage and measured in relation to the length and carapace width, abdomen width, the length and propodus height and gonopods length. A total of 4121 crabs were captured, represented by species: Megalobrachium roseum, Megalobrachium soriatum, Megalobrachium mortenseni, Minyocerus angustus, Pachycheles laevidactylus, Pachycheles monilifer, Petrolisthes armatus and Pisidia brasiliensis. Except for P. armatus, other porcellanids inhabited only the lower intertidal of the Bay. The species M. soriatum, M. mortenseni, M. angustus, P. laevidactylus and P. monilifer had restricted occurrence in the Bay. The highest diversity occurred in the foreign sector and the increased dominance in the domestic sector. Petrolisthes armatus was the dominant porcelain of the Bay, and this species is reproducing continuously on the Marambaia Island, in Prainha and Ibicuí. Only the Marambaia Island had the sex ratio of P. armatus different from the expected, in samples from 2004 to 2005. The sexual dimorphism of this species has been witnessed on the Marambaia Island and Prainha, and males are the majority in these localities. A continuous input of juvenile P. armatus was witnessed in the region of study. The species used are different strategies for growth and reproduction between Prainha and Ibicuí