Corbicula (Bivalvia: Sphaeriacea) vs. indigenous mussels (Bivalvia: Unionacea) in U.S. rivers: A hard case for interspecific competition?

Abstract

At a time when populations of indigenous river mussels have been dwindling and/or disappearing, the introduced Asian clam, Corbicula, has spread through many U.S. rivers from California to Florida. In the Arkansas River Navigation System, a heavily managed waterway, Corbicula presently has a different "competitive" presence than it does in the relatively unmanaged Buffalo River in Arkansas. Comparative studies of both Corbicula and indigenous bivalved mollusks reveal biological bases for the contrasting kinds of benthic faunal change. There are ecologically relevant, distinctive differences between the two kinds of animals: in mantle/shell and mantle/gill apparatus, in the reproductive complex and neuroanatomy, and in spawning and locomotor behaviors. It is argued that the conservative molluscan characteristics of Corbicula enable it to function in an exclusive, "contradictory" role with indigenous bivalves in a heavily managed waterway, and in a "contrary" competitive role elsewhere. Rationale is presented for incorporating organismic evaluation into studies of competition between distantly related taxa. © 1979 by the American Society of Zoologists.