Aquatic invasive species, sometimes called nuisance, noxious, or harmful alien species, primarily arrived in the Great Lakes as a consequence of human activity. These plants, animals and pathogens are dangerous because they threaten the native biodiversity and ecosystems that sustain life in the region. When it comes to invasive species in the Great Lakes, we are paying for the mistakes of the past – more than 160 aquatic invasive species now call the Lakes home.

Sometimes called “biological pollution,” invasive species can cause irreversible harm. The loss of native biodiversity could cause regional extinction of many species that have survived in this region for millennia. Invasive species add an economic burden to our communities, too. The stakes are high, and so local, state and national governments are spending billions of dollars each year in an effort to contain the problem and protect the native ecosystems that support our way of life. Unfortunately, the high cost of controlling these invaders is borne primarily by tax-payers, not those who bring them to our shores.

While most invasive species arrived in the Great Lakes region by accident, some invasive species were intentionally introduced to the region in an effort to solve other problems, such as over fishing. Today, the greatest source of aquatic invasive species in the Lakes is an unintentional one: ships’ ballast water. Cargo ships carrying about 15 million tons of goods to and from Great Lakes ports every year rely on “ballast water” to help stabilize their ships at sea. When these ships pick up new cargo, they can dump tens of thousands of gallons of ballast water – often taken from distant waters – into the Great Lakes. Even the tiniest microscopic organisms found in this ballast water can take hold and cause a significant disturbance in the Lakes.