The role of brachyuran crabs in the trophic web on the inner shelf of Ubatuba, southeastern Brazil

Abstract

The role of brachyuran crabs in the trophic web on the inner shelf of Ubatuba coast was evaluated through the stomach contents analysis. Seasonal sampling at 15, 30 and 45 m depth was carried out with an otter-trawl of 6 m mouth width, from spring 1985 to winter 1986. Two additional samples were taken at 30 m in the summer and winter of 1987. The stomach contents of 2516 specimens from Persephona mediterranea, Portunus spinimanus; Callinectes omatus, Libinia spinosa and Hepatus pudibundus were examined. These species were the most abundant in the area and presented different diets based mainly on shrimps, polychaetes and brachyuran crabs. Seasonal changes in the diet of some species were observed as being determined by the local availability of preys. Brachyuran crabs showed a carnivorous diet and most probably play a key role in the energy transfer, linking the sediment communities to the higher trophic levels. The largest crabs seem to be the top predators in the Ubatuba inner shelf ecosystem.