Rough periwinkle, Littorina saxatilis

Eradication of an Exotic Snail Littorina saxatilis in San Francisco Bay: A Model System

SERC's Marine Invasion Research Laboratory and the National Oceanic and Atmospheric Administration are collaborating on research to test the efficacy of eradication methods on a small nonindigenous marine snail in San Francisco Bay, Littorina saxatilis (Olivi, 1792). L. saxatilis is native to the Atlantic Ocean but was discovered in San Francisco Bay in 1992 (Carlton and Cohen, 1998). L. saxatilis likely invaded via the bait or live seafood trade, associated with an Atlantic alga (Ascophyllum nodosum) that is often used as packing material for shipments of live animals (Miller, 1969).

Although biological invasions constitute one of the foremost threats to the integrity of coastal marine ecosystems (Ruiz et al. 1998), there have been relatively few attempts to eradicate established invaders. General information on eradication of marine invaders is limited. A wide range of possible control and eradication measures have been considered in marine systems, including biocides, manual removal of marine invaders, and the introduction of biocontrol agents (Lafferty and Kuris, 1996). However, few of these methods have been adequately explored or tested, thus limiting our knowledge about feasibility under various conditions. A key element in the potential eradication of any established invader is to begin efforts early in the invasion process, while population densities are low and geographical ranges restricted. Also, to prevent reintroduction of eradicated invaders, effective vector management must be implemented.

Littorina saxatilis appears to be an ideal candidate for an eradication and management program (Myers et al., 2000), although no such measures have yet been implemented.  Its apparent restricted distribution in accessible locations and relatively low abundances allow targeted and concentrated removal or extermination efforts (Carlton and Cohen, 1998). In addition, its biological attributes also facilitate potential eradication, as it is a direct-developing species without a widely dispersing larval phase. Furthermore, the primary invasion vector for this species is believed to be known and can potentially be controlled by public outreach efforts.

In addition to implementing and evaluating eradication procedures, this research also will investigate those demographic conditions that influence the success of eradication. This eradication effort is critical to extirpate a known invader and serve as a model system to test feasibility and consistency of eradication and control efforts in marine ecosystems.

For more information on the rough periwinkle, Littorina saxatilis, click here.

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