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 C₃ and C₄ 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 ¹³C : ¹²C ratios of the plants; the relation between the ¹³C : ¹²C ratios of the crabs and marsh soils was less direct. The stable isotopic composition of the crab carbon was biased toward the ¹³C : ¹²C ratios of the C₄ plants.