Primary productivity within mangroves results from detrital and coprophagous interactions on the forest floor. The feeding behaviors of Sesarmid crabs (Decapoda:Brachyura) alter the structural and chemical composition of benthic sediment through the consumption and incorporation of mangrove leaf-litter. In doing so they create habitats for organisms that in turn provide an additional food source for herbivorous crabs. Species specific herbivory was observed in order to understand the implications of Sesarmid activity on sediment composition. The study was conducted at two contrasting mangrove forest sites, one in a protected area at Jozani and the other in a disturbed area at Pete in Zanzibar, Tanzania. Equal quantities of leaves from three tree species (Rhizophora mucronata, Bruguiera gymnorrhiza and Ceriops tagal) were added to experimental plots. The level of herbivory for each leaf was observed and compared in order to assess the presence of dietary preference in Sesarmid crabs. Results indicate that crab herbivory is lower in community used Pete mangroves than at the protected site. Green leaves were fed upon more than senescent yellow leaves. There was a clear preference of crabs for mature green R. mucronata leaves. The results of preferential herbivory are then applied to the larger framework of mangrove restoration. The implications of leaf preference may be an invaluable component for future reforestation projects that aim to replant trees and restore ecosystem functionality as well.
Biology | Life Sciences
Nicholson, Charlie, "Mangroves and Crabs as Ecosystem Engineers in Zanzibar" (2009). Independent Study Project (ISP) Collection. 760.