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Mail-Ordering Aquatic Plants Can Be Dangerous

Water gardening is increasing in popularity as a hobby. The peaceful sound of trickling water and the serene gliding of goldfish spread joy and peace to water gardeners. However, if water gardeners are not careful, their gardens could also spread invasive plants and animals into the local environment.

Sales in the water garden industry have reached approximately $1 billion per year. Leading the growth curve are mail-order sales of aquatic plants. To assess the potential for these sales to act as a vector of AIS release, Minnesota Sea Grant and the Minnesota Department of Natural Resources supported a study by University of Minnesota researchers who looked at aquatic plant retailers in three categories: water garden specialists, aquarium specialists, and general garden businesses. The study, by Kristine Maki and Sue Galatowitsch with the Department of Horticultural Science, examined the issues of intentional sale of illegal aquatic plants, unintentional shipment of such plants and other organisms.

They placed 40 orders for plants typically used by water gardeners with vendors across the U.S. To determine whether current regulations are effective in preventing the sale of aquatic nuisance plants, they submitted orders for those classified as noxious weeds under federal law and as prohibited exotic species under Minnesota law.

When the plants arrived, they examined them for the unintentional inclusion of other plants and organisms. The 40 orders represented a total of 123 taxa and 681 individual plants, although many additional organisms were received. In fact, 93 percent of orders contained additional plants, animals, fungi, or algae.

Ten percent of the orders included other plants classified as AIS: hydrilla (Hydrilla verticillata), giant salvinia (Salvinia molesta), purple loosestrife (Lythrum salicaria) and curly-leaf pondweed (Potamogeton crispus).

"These four plants are causing problems all around the country and are some of the most destructive aquatic nuisance plants in the world," said Maki.

As for the illegal plant orders, researchers found that 13 of the 14 orders they placed were filled, reflecting a violation rate of 93 percent.

"These findings clearly indicate the need to raise awareness among riparian land owners, water gardeners, resource managers, and policymakers regarding the risks associated with the sale and use of aquatic plants," urged Maki.

For more information about this project, order the journal reprint, Movement of invasive aquatic plants into Minnesota (USA) through horticultural trade, from Sea Grant JR 503 on the Journal Reprint order form. Or you can contact Susan Galatowitsch, University of Minnesota, (612) 624-3242 or galat001@umn.edu.

By Marie Zhuikov
September 2004

Return to September 2004 Seiche

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