Final answer:
Zebra mussels are invasive species that compete with native species for food, cause costly biofouling, and can lead to declines in native species populations in aquatic ecosystems such as the Great Lakes.
Step-by-step explanation:
Zebra mussels, Dreissena polymorpha, are invasive species that have a profound impact on aquatic ecosystems. One notable impact is their competition with native species for food and resources. Zebra mussels filter large volumes of water to extract their food, which reduces the availability of plankton, a crucial food source for native larval fish and zooplankton. This competition can lead to a decline in native species populations. Additionally, by attaching themselves to surfaces and forming dense colonies, zebra mussels cause biofouling of man-made structures such as locks, boats, and water intake systems, leading to expensive maintenance and repair costs. They also affect water quality and alter aquatic habitats by out-competing and displacing native mussels and clams.
An example of their ecological impact can be observed in the Great Lakes where zebra mussels were introduced through ship ballast water from Europe. Since their introduction, they have caused extensive economic damage, millions of dollars in clean-up costs, and significant ecological changes like improved water clarity, which has helped some species but threatened others, including the native mollusk populations.