Which invasive mussels disrupted American freshwater ecosystems and disrupted the food chain?

• A. Medically important mollusk native to North America
• B. Mussel from southern Russia that became invasive in American freshwater lakes
• C. A sea snail affecting marine ecosystems
• D. A freshwater clam native to Europe unaffected in US

Answer: (B)

Invasive species disrupt ecosystems by spreading rapidly, outcompeting native organisms, and reshaping the food web. The mussel from southern Russia that became invasive in American freshwater lakes fits this pattern because zebra mussels originated in the Black Sea region (including areas in southern Russia) and spread through U.S. freshwater systems. They are voracious filter feeders, removing large amounts of phytoplankton from the water, which reduces food for native zooplankton and fish larvae and can cascade up the food chain. Their rapid colonization also allows them to outcompete and displace native mussels, altering habitat and nutrient cycling. The other options describe native or marine species or noninvasive European species, which do not capture the invasion of U.S. freshwater ecosystems.