J. Exp. Mar. Biol. Ecol., 148 (1991) 283-294 © 1991 Elsevier Science Publishers B.V. 0022-0981/91/$03.50 283 JEMBE 01591 Effects of a burrowing mud shrimp, Upogebiapugettensis (Dana), on abundances of macro-infauna Martin H. Posey 1, Brett R. Dumbauld 2 and David A. Armstrong 2 I Department of Biological Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina, USA; 2School of Fisheries, University of Washington, Seattle, Washington, USA (Received 17 September 1990; revision received 14 January 1991; accepted 4 February 1991) Abstract: Burrowing ghost shrimp (Callianassidae) have been shown to exert a strong influence on the abundance ofmacro-infauna in soft-sediment communities, especially through reduction in the densities of many sedentary species. However, relatively little is known about the community effects of other burrowing shrimp, such as mud shrimp, Upogebia spp., that occur commonly in many estuaries of North America. A transplant/exclusion experiment was conducted to examine the effects of Upogebiapugettensis (Dana) on the abundance of other macro-infauna in a Pacific Northwest tideflat. Several numerically dominant, sedentary crustaceans and polychaetes exhibited lower abundances in the presence of Upogebia as compared to treatments where the mud shrimp was absent. The overall pattern of faunal response to the presence of U. pugettensis was similar to that reported for Callianassa californiensis (Dana), an unexpected finding given the different burrowing and feeding habits of these two crustaceans. Key words: Bioturbation; Functional group; Thalassinid; Upogebia INTRODUCTION Burrowing shrimp of the Thalassinidea form an important component of many shallow temperate and tropical marine benthic communities (Stevens, 1928; Pearse, 1945; AUer & Dodge, 1974; Dorsey & Synnot, 1980; Hill, 1981; Suchanek, 1983) and have been proposed to strongly affect local community composition (Aller & Dodge, 1974; Ronan, 1975; Suchanek, 1983; Posey, 1986a). Most studies of the community effects of thalassinids have concentrated on ghost shrimp, Callianassa and Callichirus (Callianassidae). In general, callianassid shrimp are burrowing deposit-feeders living within relatively impermanent burrow systems (MacGinnitie, 1934; Aller & Dodge, 1974). Where callianassids occur abundantly, bioturbation from their burrowing activities has been proposed to reduce numbers of tube-dwelling polychaetes and amphipods as well as clams and other sedentary organisms (Stevens, 1928; Aller & Dodge, 1974; Ronan, 1975; Peterson, 1977, 1979; Dorsey & Synnot. 1980; Brenchley, 1981 ; Murphy, 1985; Posey, 1986a). As a result of their differential effects on bottom Correspondence address: M.H. Posey, Department of Biological Sciences, University of North Carolina at Wilmington, Wilmington, NC 28403-3297, USA.