Food and habitat choice in the spider crab Leucippa pentagona (Majoidea: Epialtidae) in Bahía Bustamante, Patagonia, Argentina

Abstract

The aim of the present study was to analyze the feeding strategy and spatial distribution of the spider crab Leucippa pentagona in Bahía Bustamante (Patagonia, Argentina). Several microhabitat variables that could influence the spatial distribution of this crab were related to its different life stages by using redundancy analysis (RDA). Regarding its feeding preferences, we found that the Sphacelariales Halopteris spp. and Sphacelaria fusca, epiphytes of the red alga Gracilaria gracilis, represented over 75% of its diet. Conversely, consumption of G. gracilis was low throughout the year. These feeding preferences can be related to the higher proportion of ash-free dry mass of Sphacelariales. A close association was observed between G.gracilis biomass and recruits and mature crabs; this relationship was stronger at critical periods of the crab?s life cycle such as incubation or molt. Intermolt juveniles were related to G. gracilis as well as to other species of macroalgae. Our results suggest that G. gracilis plays a key role in the small-scale distribution of L. pentagona in Bahía Bustamante, providing food and shelter he consumption of G. gracilis epiphytes allows L. pentagona to maintain high foraging rates in safe living sites, minimizing the damage on G. gracilis.