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Transcript
Introduced Species: Impacts on Biodiversity Threats to biodiversity Scientists agree that the following five factors are the major problems contributing to the current loss of biodiversity: habitat destruction introduced species pollution overexploitation population growth Terms Alien Exotic Indigenous Native Introduced Invasive Nonnative Noxious Nuisance Bumblebee on flower of introduced thistle Introduced Species Introduced species have been moved from their native habitats to new habitats - usually by humans, accidentally or intentionally. Some introduced species become invasive in their new habitats = successfully reproduce and spread; cause economic or environmental harm or harm to human health Herb robert (Geranium robertianum) Pathways: How are species introduced? Intentional introductions for agriculture, horticulture, research, biological control Unintentional introductions through contaminated agricultural products, timber, etc. Attached to or carried in freight, packing materials, shipping containers, ships, boats, cars, planes and other modes of transport Biological attributes of invasive species This is an area of current research Difficult to generalize Usually a lag phase before a species becomes invasive - difficult to tell which introduced species will die out and which will become invasive = difficult to decide whether to make the effort to control the species at this point or not Pinpointing these attributes would provide a valuable tool for preventing invasions Theories about why some introduced species succeed: These theories take into account attributes both of the species and the communities being invaded: escape from natural constraints (predators, parasites, etc.) occupation of a niche that was vacant aided by humans, usually through disturbance of the native community Impacts on Biodiversity Invasive species can have a multitude of impacts: prey on or cause disease of native species outcompete native species for resources or breeding sites hybridization with native species habitat modification (change hydrology, encourage fire, alter nutrient cycles) agricultural/natural resource losses (pests, diseases) Impacts on Biodiversity Herb robert (Geranium robertianum) Cichlid fish English ivy (Hedera helix) Western pond turtle populations have declined, in large part due to predation by introduced bullfrogs Photo by Kate Slavens Economic Impacts of Invasive Species Loss of potential economic gain: crop production domestic animal and fisheries industries forest products Expense of fighting invasions preventing invasions (quarantine) controlling populations of invasive species eradication What is being done? Regulating Introductions In February of 1999, President Clinton signed an executive order which expands and coordinates federal efforts to address the threat of invasive introduced species and to prevent the future introduction of nonnative species. The Invasive Species Council, created by the order, has developed a National Management Plan for invasive species. www.invasivespecies.gov What is being done? Regulating Introductions Invasive species, once established, are very difficult to eradicate prevention of invasions is key International treaty: Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) WTO members can restrict movement of species that may pose a threat to human, animal or plant life What is being done? Regulating Introductions Animal and Plant Health Inspection Service (APHIS) of the Department of Agriculture attempts to prevent the introduction of nonnative agricultural pests and diseases focused mainly on protecting agriculture, but also serves to prevent ecosystem damage caused by nonnative species and diseases What is being done? Eradication and Control Methods of eradication: chemical mechanical (including manual) biological Often, eradication efforts are too little, too late If eradication fails, then maintenance control is the goal same methods as for eradication The goal is to maintain or increase native species diversity and to maintain a functional ecosystem that leads to that level of diversity (may have to accept invasives in the mix). What is being done? Eradication and Control Efforts to eradicate foxes in Western Australia What can you do? In the garden - choose native plants and pull exotic weeds Do not release exotic pets or dump aquariums containing exotic pets or plants Avoid transporting fresh fruits, vegetables, grains or meats across state or country lines Volunteer to control invasive species or plant native species in a local natural area Be aware of the issues and help to educate others Not if you can help it! Produced by Woodland Park Zoo Education Department 2001 Photo credits: All photos by K. Remine/M. White except: Slide 11 - Western pond turtle by Kate Slavens. Used with permission.