Predators of the Invasive Mussel Musculista senhousia

Musculista senhousia (Benson in Cantor, 1842) is a soft sedimentdwelling mussel that has spread anthropogenically from its native Asia to North America, Australasia, and Europe. This byssal mat-forming species can become overwhelmingly dominant and have dramatic impacts within invaded ecosystems, but its invasion may meet "ecological resistance" from native predators. In Mission Bay, San Diego, California, three fish species and two shorebirds were found to prey upon the mussel. Experimental results suggest that predation can dramatically impact intertidal mussel populations and may account for observed seasonal declines in the species. Despite the creation of a byssal cocoon, which may afford the mussel some protection, several taxa worldwide have been found to be Musculista predators. In addition, in areas where the mussel is native, humans impact mussel populations by gathering it for animal feed or bait, or to remove it from commercial shellfisheries grounds. NONNATIVE SPECIES are increasing in abundance throughout the world, and biological invasions now represent one of the most serious threats to the integrity of ecosystems (Vitousek et al. 1997, Mooney and Hobbs 2000). Exotic species can have a wide range of ecological interactions within invaded ecosystems, including competition with natives, alteration of the physical nature of habitats, or predation upon resident biota (Crooks and Khim 1999, Parker et al. 1999, Ruiz et al. 1999). Exotics also can be eaten by natives, which can provide food resources for resident biota as well as potentially liInit the abunI Portions of this work were funded by a grant from the National Sea Grant College Program, National Oceanic and Almospheric Administration, under grant no. NA66RG0477, project no. RlCZ-150 through the California Sea Grant College System. The views herein are those of the author and do not necessarily reflect the views of NOAA or any of its subagencies. The U.S. Government is authorized to reproduce this paper for governmental purposes. Manuscript accepted 26 February 2001. 2 SJnithsonian Environmental Research Center and Romberg Tiburon Center, 3152 Paradise Drive, Tiburon, California 94920-0855 (phone: 415-338-3531, fax: 978~28-2661.E-mail:[email protected]). Pacific Science (2002), vol. 56, no. 1:49-56 © 2002 by University of Hawai'i Press.