Feeding Ecology and Ecological Role of North Brazilian Mangrove Crabs

Abstract

AbstractWe describe feeding guilds of mangrove crabs in the Caeté estuary (north Brazil), aspects of their feeding behavior and food consumption rates, and discuss their ecological role. Ucides cordatus and Aratus pisonii eat mainly senescent and fresh leafs, respectively, while fiddler crabs (Uca spp.) and Pachygrapsus gracilis are the most important deposit feeders. Goniopsis cruentata is the dominant omnivore, feeding on plant material, detritus and other crabs alike, while the mud crab Eurytium limosum is the most important carnivorous crab in the intertidal. Feeding periodicity and daily food intake (DFI) differed between feeding guilds. While U. cordatus feeds more or less continuously, fiddler crabs and P. gracilis only feed during low tide, mostly during the day. E. limosum feeds only during high tide. Deposit feeders had the highest daily food intake with 22–32% of bodyweight, followed by the herbivorous U. cordatus (6.4 %), and the predator E. limosum (6.2%). U. cordatus eats over 80% of the litter and propagule production in the forest, returning it as finely shredded detritus via their feces. Mangrove trees, leaf consuming and deposit-feeding crabs, and microbenthos form a positive feedback loop that enhances nutrient remineralization, and probably promotes primary and secondary production. Mangrove trees benefit as (1) nutrients and energy are retained in the system, (2) nutrient remineralization is enhanced, and (3) the soil is aerated by the crabs, diminishing anoxic conditions and production of phytotoxins in the sediment.KeywordsMangrove EcosystemDeposit FeederDaily Food IntakeFiddler CrabMangrove TreeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.