Ecology of the spider crab Libinia ferreirae (Brachyura: Majoidea): ontogenetic shifts in habitat use

We described the ecology of the spider crab Libinia ferreirae testing the habitat segregation during the ontogenetic shifts. Collections were performed monthly by trawling along the coastal area of Cananéia, São Paulo State (southeastern Brazil). Medusae were examined for the presence of any symbionts, and crabs were classified as juveniles (abdomen sealed to the sternite), adults (unsealed abdomen), and ovigerous females (embryos adhered to the pleopods). The environmental factors related to the water column were obtained using a multiparameter probe. In total, 564 adults and 357 juveniles were collected. However, all juveniles were obtained in association with Lychnorhiza lucerna medusae. An increase in the abundance of ovigerous females was observed as chlorophyll levels (phytoplanktonic production) increased, which is consistent with the patterns proposed for crustaceans with planktotrophic larval stages, i.e., the association of larval hatching with oceanic productivity could explain the success in juvenile recruitment approximately two months after the peak in the abundance of ovigerous females (cross-correlation: r = 0.96). This spider crab shows an ecological strategy of habitat segregation among juvenile and adult individuals, thus avoiding competition for resources among different life cycle stages.