In the water, zebra mussels open their shells to let in organic material and plankton. Because many underwater species need this organic material to survive, zebra mussels are essentially causing native species to starve. Freshwater mussels are the most endangered species in the United States because of invasive mussels.

Zebra mussels also release phosphorous into the water. Because phosphorus is a commonly used fertilizer, it causes plants to grow rapidly. Increasing levels of rapid plant growth decrease oxygen levels in the water and hurt, even suffocate, native species.

Zebra mussels, like milfoil, can reproduce quickly and develop large masses that cover the undersides of docks, boats and even completely cover freshwater mussels. They can clump so close together that they block off pipelines used by cities for their water supply.

North America spends billions of dollars a year to address the impacts of invasive zebra mussels.