Evaluation of the stomach contents of Eriphia gonagra from a rocky shore in the southeastern Brazilian coast

ABSTRACT The rocky shores of Praia Grande, in Ubatuba (São Paulo, Brazil), are formed by rock and Sabellaridae polychaete sandy reefs. These microenvironments offer shelters and foraging areas for several marine organisms and attracts many tourists. The crab Eriphia gonagra (Fabricius, 1781) inhabits these structures and can be used as a bioindicator, since they may be affected by anthropogenic actions. This study evaluated the stomach contents and characterized the feeding habits of an E. gonagra population, inhabiting the rocky shores from Praia Grande, taking into account the sex, size, and microhabitat. Monthly samplings were performed in 1996 and 1997 and the crabs were manually captured on the rocky surface or into of the sand reefs. So, the specimens sampled were characterized according to their capture site (microhabitat) as rocky (RO) or sand reef (SR). The most abundant food items were Mollusca, algae, Polychaeta, and Crustacea, being observed the importance of these groups as a nutritive resource in the studied environment. Mollusks were more abundant in the stomachs of crabs sampled on the rocks, while the other items increased in the sand reefs crabs. In the specimens sampled in the SR, polychaetes were the item food more common, indicating that this biotope is also used as a rich source of protein. The proportion of items differed also between size classes. Knowledge of such habits is essential for nutritional requirements studies, monitoring relationships among organisms, as well as assessing future environmental impacts in consolidated coastal regions. RESUMO O costão rochoso de Praia Grande (Ubatuba, SP) é formado por matacões rochosos e recifes de areia formados por poliquetas sabelarídeos. Essas estruturas oferecem abrigo e área de forrageamento para diversos organismos marinhos, e atraem muitos turistas. O caranguejo Eriphia gonagra (Fabricius, 1781) habita essas estruturas, podendo ser utilizado como bioindicador, uma vez que estas podem ser afetadas por ações antrópicas. Por meio deste estudo avaliou-se o conteúdo estomacal e caracterizou-se os hábitos alimentares de uma população de E. gonagra, levando em consideração o sexo, tamanho e microhabitat. Amostragens mensais foram realizadas em 1996 e 1997 e os caranguejos foram capturados manualmente na Praia Grande. Assim, os espécimes amostrados foram caracterizados de acordo com o local de captura (microhabitat) como recife rochoso (RO) ou de areia (SR). Os itens mais abundantes foram