Zebra mussels have now found their way to the United States from the Caspian Sea and sought to settle, originally, in Lake St. Clair when the ballast water brought them. From there, zebra mussels spread and wreaked havoc on the environments and its biodiversity, particularly on Presque Isle. Zebra mussels are zooplankton and phytoplankton filter feeders, making the water clearer, but not cleaner. They have had a negative impact on the existence of clams, walleye and many other organisms. To preserve the biodiversity of Presque Isle, zebra mussels must be removed and controlled. Several methods can be used to achieve this goal: chlorination, poison, scraping, etc. What are invasive species? Invasive species are non-native organisms that occupy habitats and disrupt the natural ecological cycles of the habitat. They threaten the biodiversity of an ecosystem and are biological pollutants. Invasive species introduced to new habitats generally maximize their reproduction in their new home and crowd out native species. Their lack of natural predators in their new community allows for proliferation of growth and expansion due to their abundant food supply. Once established, invasive species can rarely be eliminated because their new habitat is favorable for their survival. Introduction to Zebra Mussels Zebra mussels, also known as Dreissena polymorpha, are small freshwater mollusks that invade American rivers and lakes. They originate from the Balkans, Poland and the Soviet Union. In 1988, they were discovered in a small body of water connecting Lake Huron and Lake Erie, known as Lake St. Clair. Biologists believe the optimal temperature of zebra mussels in a ship's ballast water, middle of paper, may affect their reproductive cycle. When water temperatures reach around 13°C, zebra mussels breed in Lake Erie. Eggs are fertilized when eggs and sperm are released into the water, which then develop into free-floating larvae called veligers. The larvae are transported by water currents, allowing them to expand their distribution. For approximately 10 to 15 days, the larvae are in the planktonic stage. After this stage, the veligers look for a place to attach and attach themselves using elastic fibers called byssal threads. The moment when mussels begin to form their shells is called the settling phase. If the water temperature is heated beyond its optimal temperature, then the zebra mussels will be in anaerobic conditions and will be stopped in their reproductive process..