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Invasive Species Invasive Species • Apparently harmless animals and plants that are transported around the world. • In their new habitats invasive species reproduce rapidly because they lack predators that keep their population in check. Purple Loosestrife • Brought to America from Europe in the 1800’s as an ornamental plant. • Destroys native wetland ecosystems Purple Loosestrife • No herbivores eat this flower so it grows very rapidly and displaces native plant species. Native cattails are endangered because Purple Loosestrife is taking up its space! Zebra Mussels • Brought over on cargo ships during the 1980’s and are destroying the Great Lakes ecosystems Zebra Mussels Gypsy Moths • A native of Europe they were brought accidentally to the US in the 1880’s • They defoliate native trees like aspens Sea Lamprey • Brought over from Europe on cargo ships the Sea Lamprey has killed many native fish in the Great Lakes Sea Lamprey attach to other fish and “suck” out their guts! Control of Invasive Species • Biological Control – using a predator from its homeland THAT WILL ONLY EAT THE TARGET SPECIES to kill native species or at least control it. Leaf Eating Beetles and Purple Loosestrife 1 Year After Beetles Introduced Before Beetles Introduced Pesticide Use and Fertilizer Use Pesticide & Fertilizer Use • Pesticides are used to kill insects and protect crops/plants • Fertilizers are used to increase the growth rate of crops/plants Ecological Problems with Pesticides • Pesticides are dangerous chemicals that trickle down into ground water aquifers. Biological Magnification • Chemicals accumulate or build up as it goes up the food chain often becoming lethal • As a general rule, every step up on the food chain these toxins are found, they are magnified about 10 times. Biological Magnification • Pregnant women are told not to eat seafood due to biological magnification of chemicals, like mercury that can be harmful to the fetus Where Does Mercury Come From? • Mercury is the most toxic non-radioactive element in the world and it is released when coal is burned. • Mercury falls to the ground and is distributed to streams, rivers and lakes and to the oceans where it is consumed by bacteria and becomes methyl-mercury, an organic form that is then easily absorbed by plankton and zooplankton. • Mercury is an immortal element; there is no way to get rid of it once it is released in the environment. DDT Biomagnification and the Bald Eagle • DDT a pesticide to kill mosquitoes • Harmed the shells of Bald Eagles bringing them close to extinction DDT Pesticide • Wide scale use of DDT banned in 1972 Stockholm Convention • Toxic to humans & animals when absorbed or swallowed. • Limited use today as disease vector control • The Bald Eagles are BACK! Ecological Problems with Fertilizers • Fertilizers contain high levels of nitrogen and phosphorus that runs off into streams and marine ecosystems causing algae blooms. Algae Bloom • When nitrogen levels in rivers and streams increase, they aid in algae overgrowth. As algae dies and decomposes, organic matter in the water increases. This process uses up oxygen, causing levels to drop. Without the oxygen, fish, crabs and other aquatic life die. Solutions - Organic • • • • Organic pesticides to kill pests Limit use of fertilizers Hand pull weeds Crop rotation – alternating the crop grown each year. • Using pests to fight pests - Integrating predatory insects into a farm, such as ladybugs or predatory mites, can help kill off pests.