In the late 1980s, zebra mussels were accidentally introduced into the Great Lakes of North America through the ballast water of cargo ships. These small, striped mollusks originally come from the Black Sea and the Caspian Sea. Once established, zebra mussels have become a major ecological and economic problem. A single female can produce up to one million larvae per year, leading to dense colonies of up to 30,000 individuals per square meter. Their ability to attach to solid surfaces using filaments called byssus allows them to colonize a wide range of man-made structures, including pipes, water treatment plants, power plants, fire hydrants, and even nuclear reactors. The resulting maintenance and cleaning costs have reached hundreds of millions of dollars annually. Zebra mussels filter water to feed on plankton, which has led to visibly clearer lakes. However, this increased water clarity has disrupted local food chains, as many aquatic species rely on the cloudiness of the water for protection and feeding. Additionally, the filtering process complicates the supply of drinking water by altering its chemical composition and increasing the need for treatment. In response to the threat posed by invasive species like zebra mussels, the United States and Canada introduced regulations in 2006. These required ships to rinse their ballast tanks with seawater before discharging the water, aiming to reduce the introduction of new invasive species. A 2019 assessment found that only three new invasive species had established themselves in the Great Lakes between 2006 and 2018, and none were attributed to ballast water discharge. Despite these measures, zebra mussels have not been eradicated and have permanently established themselves in 32 U.S. states. Their close relative, the quagga mussel, has also spread widely, being recorded in 19 additional states. While efforts have reduced the risk of new invasions, the presence of these mussels continues to pose challenges for environmental and economic management in the region.