New study examines the role vendors play in spread of invasive species

Author: William G. Gilroy

Eurasian watermilfoil, Asiatic clams, yellow flag iris and rusty crayfish may not be on your shopping list, but a new study by invasion biologists at the University of Notre Dame reveals that these and other aquatic invasive species are most likely for sale at a retailer near you.

Harmful, non-native speciesfrom combustible cheat grass to voracious carp to the West Nile virusare spreading intoU.S.lands and waters at an accelerating pace. Once they arrive in their new environments, some of these species threaten valued environmental, agricultural or personal resources. Scientists believe that at least 183 aquatic non-native species currently live in theGreat Lakesand a new species is discovered, on average, once every 28 weeks.

Notre Dame Biologist David Lodge and postdoctoral researcher Reuben Keller attempted to determine whether commercial vendors are contributing to the introduction and growth of invasive species. They undertook a shopping expedition to nurseries, pet shops and fish markets inChicagoand the southernGreat Lakesregion, as well as doing some shopping over the Internet.

The researchers discovered that not only were many invasive and potentially invasive species easily obtainable, but many often were misidentified.

Most animals were identified by common name only, such as ‘goldfish,and even though scientific names were more often applied to plants, consumers cannot be certain what species they are receiving because misidentification is common,Keller said.

Nurseries proved to be a particular cause for concern, he said.

Water gardening poses the greatest risk for new introductions and invasions,Keller said.It is a booming business, increasing each year, and home owners often want new and unusual plants. And many vendors are selecting non-native species that are capable of surviving outside.

Adding to the problem, according to the biologists, is the fact that many of these plants are accompanied byhitchhikers,insect and animals species that are already invasive or possess the capability to become so.

Ninety percent of the plants we ordered for contaminant analysis arrived with associated live invertebrate animals (i.e, snails, shrimp, etc.),Keller said.

Among the plants Keller and Lodge obtained were some already well-known problem invaders in the Great Lakes region, including yellow flag iris, water chestnut and Eurasian watermilfoil, the latter of which can be found in lakes throughout Indiana and interferes significantly with boating, fishing and swimming.

The researchers also found eight plant species for sale that are not currently established in theGreat Lakesregion, but that are invasive in temperate or colder environments elsewhere. These species pose a high risk of becoming invasive if they remain in trade.

Keller and Lodge also point out that vendors in live organisms benefit society in many ways, and steps to reduce invasion risks should be developed without causing serious damage to these trades.

Our work has shown that national and state policy goals of preventing the introduction of new invasive species and the spread of established invaders are unlikely to be met unless there are changes in the species sold by the trades (vendors) in live aquatic organisms, in ways of determining which species should be in trade, and in the practices regarding contaminants,Keller and Lodge note.

There are recent indications that policy makers are responding to research from invasion biologists like Lodge and Keller. The city ofChicagopassed an ordinance May 9, spearheaded by Mayor Richard Daley following a meeting with Lodge last summer, that bans 28 threatening aquatic species, including some discovered by Lodge and Keller atChicagoarea nurseries.

The Notre Dame biologists also are among a group of scientists, aquarium and water garden representatives organized by Doug Keller, director of the Indiana Department of Natural ResourcesAquatic Invasive Species Program, to manage the problem of invasive species.

Keller and Lodges study, funded by the Illinois-Indiana Sea Grant, appears in the May edition of the journal BioScience.

* Contact: * _David Lodge, director of the Center for Aquatic Conservation, 574-631-2849, , and Reuben Keller, postdoctoral research associate, 312-804-7686, .

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