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Invasive and Exotic Species. Doyle L. Crosswhite Geosciences Department University of Arkansas. What is an invasive species?. U.S Environmental Protection Agency. 2007.
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Invasive and Exotic Species Doyle L. Crosswhite Geosciences Department University of Arkansas
U.S Environmental Protection Agency. 2007. “Invasive species means an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.”
U.S. Department of Agriculture. 2007. “non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” “Invasive species can be plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions.”
Charles Elton, 1958 Ecological Explosion- “an enormous increase in numbers of an organism previously held in check by other forces.” Population Explosion
Natural Barriers to Species Interchange • Glaciers • Oceans & Currents • Mountain Ranges • Freshwater Bodies • Predation and Competition
Ballast Water Boat Hulls Aquiculture Escapes Intentional introductions Aquaria Releases Live Food Industry Vehicular Transport Escaped Ornamentals Cross-basin Connections Fish Bait Releases Illegal Stocking Domestic->Feral Solid Waste Disposal Biological Control How are exotic/alien species become established?
Zebra Mussel Nutria Ringneck Pheasant Fire Ant House Sparrow European Starling Bermuda Grass Mexican Fruit Fly Cord Grass, Spartina Striped Bass Sea Lamprey Brown-headed Cowbird Cattle Egret Some Examples
Some Consequences • Economic • Environmental • Human Health • Agricultural Pests • Species Extinctions
Management of Invasive Species • Quarantine • Eradication • Biological Control
Cowbird Biology • native range- Great Plains • “brood parasites” • range expansion • >220 host spp.
Asiatic Clam • Indigenous to Asia & east to Mediterranean, Australia and Africa • North America 1924 • habitat preferences • high fecundity- 400 larvae/day • densities- 20,000 clams/m2