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Marine Ecology Progress Series

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MEPS 119:139-154 (1995)  -  doi:10.3354/meps119139

Feeding ecology of the velvet swimming crab Necora puber in mussel raft areas of the Ría de Arousa (Galicia, NW Spain)

Freire, J., González-Gurriarán, E.

The feeding ecology of the velvet swimming crab Necora puber (Decapoda: Portunidae) in 3 mussel raft culture areas of the Ría de Arousa (Galicia, NW Spain) was studied through the analysis of stomach contents. The dominant prey was Pisidia longicornis (50 to 81% of the diet in the different areas), a small epifaunal anomuran crab that inhabits culture ropes. Other important food components were brachyuran crabs, the mussel Mytilus galloprovincialis and other bivalves, gastropods, egg cases of the gastropod Nassa spp., the echinoid Psammechinus miliaris and fishes. Plants (both eelgrass and seaweeds), sponges and polychaetes constituted secondary prey, with low quantitative importance. Habitat was the most important factor in diet variability within the ría, related to the spatial differences in abundance and structure of the benthic and raft epifaunal communities. Also, important differences were observed between the diet in soft bottom areas of the Ría de Arousa and rocky zones in other geographical areas, where the importance of seaweeds was higher. The diet of N. puber was dominated by raft epifauna and mussels, and also by the megabenthos. Macroinfauna and plants showed little quantitative importance. For the epifaunal prey, P. longicornis was selected positively and amphipods negatively; in the case of the infauna, bivalves and ophiuroids were selected positively, and polychaetes negatively. Diet variability related to life history was due mainly to ontogenetic changes. Fishes, brachyurans, mussels, echinoids and sponges increased their contribution to the diet with growth, but P. longicornis, egg cases of Nassa spp., and the holothurian Aslia lefevrei presented the opposite pattern. The relationship between body size and gut fullness presented a negative allometry, but absolute food consumption increased with size. Food consumption variability was linked mainly to intermoult stage and season. During the immediate premoult and postmoult, there was no food ingestion; however, gut fullness was higher in the recent postmoult compared to intermoult animals. Seasonal changes were due to higher food consumption in autumn and winter.

Feeding . Diet . Mussel culture . Ría de Arousa . Necora puber . Portunidae

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