Relation between the stable carbon isotope composition of fiddler crabs, plants, and soils in a salt marsh1

Abstract

The fiddler crab Uca pugnax consumes detrital material on the soil surface in monospecific and mixed species stands of C 3 and C 4 plants in Georgia salt marshes. The carbon isotopic ratios of U. pugnax collected in eight separate areas of a salt marsh were linearly related to the 13 C : 12 C ratios of the plants; the relation between the 13 C : 12 C ratios of the crabs and marsh soils was less direct. The stable isotopic composition of the crab carbon was biased toward the 13 C : 12 C ratios of the C 4 plants.