Invasive Species in Large River Systems

Moderators: Jill Hardiman*, Tim Counihan and Ian Waite
Emails: jhardiman@usgs.gov; tim_counihan@usgs.gov and iwaite@usgs.gov

Date: Thursday, September 15, 2005
Time: 8:00 am to 5:40 pm
Location: Egan 5

Invasive species threaten the biological integrity of our nation’s large rivers and the economic health of communities across the United States. Damages of more than $138 billion per year have been attributed to invading non-indigenous species (Pimentel et al. 2000). Of the 958 species listed as endangered or threatened, about 400 are considered at risk because of interactions with non-indigenous species (Pimentel et al 2000). Invading aquatic weeds alone, have resulted in millions of dollars in recreational losses (Pimentel 2000), control measures (OTA 1993), and losses in long-term value of fisheries due to drastic habitat changes. Non-indigenous fish species also have adverse effects on aquatic ecosystems and native biota. Interactions between non-indigenous and native fish species have resulted in 44 fish species classified as either threatened or endangered (Wilcove and Bean 1994). Even when economic benefits associated with some non-indigenous fish species are considered, economic losses from non-indigenous fish are more than $1 billion dollars annually (Pimentel et al. 2000). Furthermore, intentional and accidental introductions have resulted in 88 non-indigenous species of mollusks becoming established in the United States (OTA 1993). The zebra mussel Dreissena polymorpha and the Asian clam Corbicula fluminea have become serious pests. Damage costs associated with just the Asian clam are estimated at approximately $1 billion dollars annually (Isom 1986, OTA 1993). Many ecological factors can cause non-indigenous species to become abundant and persistent but primarily the lack of natural enemies and/or by being effective predators and highly adaptive in the new ecosystem. Artificial and disturbed aquatic habitats often provide favorable conditions for invasive species. Being consistent with the USGS Invasive Species Program we will provide a format for discussion of information on invasive species management-oriented research needed to prevent, detect, control, and eradicate invasive species and restore impaired aquatic systems.

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