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3 | Other species making headlines
Several other recent invaders of the Great Lakes also are cause for serious concern. The spiny water flea and the fish-hook flea, nearly microscopic crustaceans, are gradually replacing their native counterparts. With long spines that make it more difficult for fish to capture and digest them, these invaders are destabilizing the food chain at its base.
Goby (pronounced "go-be") populations are expanding explosively in the Great Lakes and displacing native species. The goby is a bottom-dwelling fish known for being aggressive, voracious feeders that can forage in total darkness. Since gobies feed on bottom-dwelling organisms and in turn are fed upon by bass, they provide a direct link by which the entry of contaminants into the food chain is accelerated (terminating in human consumption of bass). Another non-native fish, the Eurasian ruffe (pronounced "ruff"), discovered in Lake Superior in the mid 1980s, are expanding their range rapidly with as yet unknown consequences for the native species with which they interact.
The potential for the accidental importation of fish diseases (caused by microscopic invaders) is a growing concern to the Great Lakes community, which relies on the fishery to support a multi-billion-dollar industry. Such invasions have occurred in other parts of the world, and recognition of the vulnerability of the Great Lakes fishery to similar attacks is increasing. The related potential for the importation of human disease-causing organisms, including those responsible for "red tide" and associated shellfish poisonings, is also of growing concern.
Nonindigenous aquatic plants, such as purple loosestrife, Eurasian watermilfoil, hydrilla and water hyacinth, quickly establish themselves and can displace native plants. Environmental and economic problems caused by these weeds include impairment of water-based recreation, navigation and flood control; degradation of water quality and fish and wildlife habitat; and accelerated filling of lakes and reservoirs.
Graphics: Round Goby, courtesy of Dave Jude/Univ. of Michigan, Center for Great Lakes and Aquatic Sciences; Purple Loosestrife at Saginaw Bay on Lake Huron, courtesy Karen Holland/U.S. EPA.