Selective geochemistry of iron in mangrove soils in a semiarid tropical climate: effects of the burrowing activity of the crabs Ucides cordatus and Uca maracoani

Bioturbation by crabs may affect processes associated with organic matter decomposition in mangrove soils. This study examines how two crabs (Uca maracoani and Ucides cordatus), which are of substantial ecological and economic importance in semiarid coastal areas of Brazil, affect biogeochemical processes in mangrove soils. For this purpose, the physicochemical and geochemical parameters of the soils at different sites were analyzed. The redox potential was always positive at bioturbated sites (+12 to +218 mV), indicating more oxidizing conditions conducive to the oxidation of pyrite and precipitation of oxyhydroxides. In contrast, anoxic conditions prevailed at the control site (Eh