Why are zebra mussels considered harmful invasive animals in the Great Lakes?

Zebra mussels (Dreissena) are considered harmful invasive bivalve mollusks in the Great Lakes due to their rapid proliferation and destructive impact on ecosystems and infrastructure.12

Their presence causes significant harm through several mechanisms:

• Ecological Disruption: By voraciously consuming phytoplankton, they disrupt the aquatic food chain that supports native fish species. This competition for resources, combined with their tendency to colonize surfaces, has driven many native mussel species toward extinction.12
• Commercial and Structural Damage: They adhere in massive clusters to virtually any submerged surface, including bridge abutments and water-intake pipes. This clogging of infrastructure causes severe and costly commercial damage.12

Introduced to North America around 1986, likely via ship ballast water, these pests have successfully invaded all the Great Lakes and continue to spread to inland waterways, posing a persistent threat to biodiversity and human-made structures.123