Ecologia populacional de Clibanarius symmetricus (Anomura: Diogenidae) em uma praia exposta da Costa Amazônica Brasileira

Abstract

The hermit crab Clibanarius symmetricus has a wide geographical distribution along the Western Atlantic where is a conspicuous species in intertidal and shallow waters of several ecosystems as sandy beaches, tidal flats, mangroves and rocky shores. However, information on the life history traits of this species is in general limited to the subtropical regions. Here, we access the population structure and dynamics, and the shell occupation pattern of a C. symmetricus population inhabiting a rocky outcroup of an exposed sandy beach on the Amazon coast. For this purpose, monthly samplings were carried out from October 2015 to September 2016. Higher density of C. symmetricus occurred in the drier season and the frequent presence of ovigerous females suggests continuous reproduction. The overall sex-ratio was skewed toward females (0.6:1, M:F) and sexual dimorphism was recorded. Males and females had similar curvature, but smaller growth performance index than others subtropical populations. The turnover rate (P/B) was also similar between sexes as a consequence of similar growth constant. Thaisella coronata was the most occupied (97.1%) gastropod shell and the overlap in shell utilization by hermit crabs of same size may reflect competitive interactions. Also, some difference in occupation between sexes was documented, suggesting that males can occupy larger and more suitable shells.