The overall hypothesis we tested was that juveniles prawns living within mangrove creeks derive significantly greater nutritional benefits from mangrove detritus than do juveniles and adults living offshore. We used a multiple isotope approach (carbon, nitrogen, and sulfur) to elucidate the degree to which juvenile and adult prawn collected from the various habitats were utilizing mangrove detritus. The advantage of this triple isotope technique compared with the single carbon isotope analysis of Rodelli et al. (1984) is that it potentially allows more positive discrimination between different food sources in the diet of test organisms.