1. Once prized for their lovely pink and purple flowers, water hyacinths are quite invasive in a water garden, partly due to its very fast reproductive system. Old World to Florida Ukraine to Lake Erie South America to southern United States Atlantic Coast to Great Lakes
2. Chinese mitten crabs are unique in that they can migrate very long distances.  They will even leave water to walk around structures. South Korea to San Francisco Bay Ohio, Kentucky & Tennessee to Minnesota, Wisconsin, and Lake Ontario Old World to Florida Western Europe to Alabama, Arkansas, and Colorado
3. Quagga mussels are like zebra mussels in that they both have striped shells.  However, the shape of the shells is what sets the two apart. Atlantic Ocean to Lake Michigan and Lake Huron Ohio, Kentucky & Tennessee to Minnesota, Wisconsin, and Lake Ontario South America to southern United States Caspian Sea to Lake Erie
4. White perch are detrimental in the Great Lakes because they eat the eggs of popular sportfish like walleye and white bass.  The result is a decline in native fish and a competition for food among the predatory fish.  Ukraine to Lake Erie South Korea to San Francisco Bay Atlantic Coast to Great Lakes Western Europe to Alabama, Arkansas, and Colorado
5. In terms of invasive species, hydrilla is very bad plant.  Once established, hydrilla can completely cover lakes and clog up public water supplies.  Unfortunately, an effective control has not been found that will eliminate established hydrilla beds. Atlantic Coast to Great Lakes Old World to Florida Ohio, Kentucky & Tennessee to Minnesota, Wisconsin, and Lake Ontario Atlantic Ocean to Lake Michigan and Lake Huron
6. Rusty crayfish can harm an ecosystem by depriving native crayfish of food.  Being very prolific, they can quickly create an unbalance in native species. Western Europe to Alabama, Arkansas, and Colorado Ohio, Kentucky & Tennessee to Minnesota, Wisconsin, and Lake Ontario Ukraine to Lake Erie South Korea to San Francisco Bay
7. Eurasian Rudd is thought to be a competitor for food and space.  Adding an invasive species to an established waterbody can create problems both with the ecosystem within the water and possibly even outside the water. South Korea to San Francisco Bay Old World to Florida Atlantic Coast to Great Lakes Western Europe to Alabama, Arkansas, and Colorado
8. Alewives are another example of an invasive species competing for good.  The population of alewives in the Great Lakes grew in part to the decrease of larger predatory fish - a decrease caused by another invasive species, the sea lamprey. Atlantic Ocean to Lake Michigan and Lake Huron Ukraine to Lake Erie South Korea to San Francisco Bay Ohio, Kentucky & Tennessee to Minnesota, Wisconsin, and Lake Ontario