Invasive Species For Sale at Local Stores

Gardeners and pet owners might inadvertently release new invasive species into the environment, an investigation of plant and pet stores discovers.

Some of the non-native aquatic plants and animals for sale in the Chicago - Detroit region could move into the Great Lakes basin.

Other items available in the area's retail stores have already become established and disruptive exotic organisms in the region's waters.

In the area's stores, researchers discovered six plant and two animal species that don't yet reside in the Great Lakes watershed, but have successfully invaded temperate waters elsewhere. One animal for instance, the African clawed frog, now lives in California and the United Kingdom.

Millions of dollars have been spent blocking bigmouth carp from escaping into the Great Lakes drainage from the Mississippi, where it has caused considerable economic and environmental hardship. Nevertheless, anyone can buy a bigmouth carp live from food stores in the Great Lakes region. Chicago has only recently banned their sale.

Also worrying are the readily available plants and animals, that are already established and wreaking havoc. Eurasian milfoil, for which huge sums of money is allocated to its control, can be bought at plant nurseries. Rusty crayfish is sold as live bait, yet when let loose it upsets ecosystems and harms native fish.

Most imported plants and animals for sale are not accurately identified with scientific names, making it difficult for a retailer or purchaser to be aware of when they are dealing with something harmful. Even more elusive however, are the hitchhikers riding along on the plants sold at nurseries.

The worst offenders are floating small-leaved plants marketed for outdoor pond gardens. One hundred grams of the plants carries an average of 660 other living organisms that could have arrived from anywhere on the planet. Nearly all of the hidden free-riders are gastropods, creatures such as snails and slugs. Some gastropods, like the New Zealand mudsnail, are already unwelcome invaders in the region.


Reuben R. Keller and David M. Lodge. 2007. Species Invasions from Commerce in Live Aquatic Organisms: Problems and Possible Solutions. Bioscience. 57(5): 428-436.

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