Lake St. Clair Coastal Habitat
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Aquatic and Wetland Invasive Plants


Photo: Victoria Pebbles, Great Lakes Commission

The Lake St. Clair region has many invasive species found throughout the larger Great Lakes region. While there are limited studies of the impact of these invasive species specific to Lake St. Clair, experts believe that continued introduction of invasive species is one of the greatest threats to the area's biodiversity.

Phragmites australis or common reed is a very aggressive, perennial wetland grass that grows up to 13 feet tall, and is found frequently in roadside ditches and detention ponds. It is a native of the Americas and Eurasia but the highly invasive form that is rapidly colonizing U.S. wetlands originated in Europe. Phragmites produces seed but usually spreads via underground rhizomes, particularly where the soil has been disturbed. It successfully out-competes most non-woody native wetland plants due to its height and density. Dense stands of these invasive species choke out native wetland species that may be important foods for wildlife and fish.

Purple Loosestrife is a native European plant species that has aggressively invaded North American wetlands, lakes and rivers. It spreads rapidly in areas where soil has been disturbed and can often be found in retention ponds and drainage ditches. Once established, purple loosestrife can out-compete native vegetation to become the dominant vegetation. It crowds out other plants and significantly reduces biodiversity and degrades habitat quality by displacing native plants and eliminating food and shelter for wildlife and other species. The Galerucella beetle, a natural enemy of purple loosestrife, has been credited with wiping out large stands of this invasive species in southern Michigan.

Eurasian water-milfoil is native to Europe, Asia and northern Africa and was introduced to the United States by the aquarium industry. It has been spread intentionally by fishermen who introduced it to lakes for fish habitat and accidentally by recreational boaters who inadvertently carried it to other waters. Once established, it forms dense cover that shades out native vegetation, alters species composition of aquatic invertebrates, and impairs fish spawning. It also negatively impacts water recreation activities such as swimming, boating and fishing due to its dense growth.

The Great Lakes Panel on Aquatic Nuisance Species engages in ongoing efforts to prevent and control the occurrence of aquatic nuisance species in the Great Lakes.

For more information, see: Coastal Habitat Plan, Section V (PDF)