Human Impacts on Biodiversity many species have become extinct throughout earth’s history mass extinctions have resulted from asteroid collisions, volcanic eruptions leading to drastic climate change. there is currently another mass extinction happening on earth. about 12% of the bird species on earth are endangered about 37% of fish in the world are at risk The main threats to biodiversity are: habitat loss invasive species pollution overexploitation climate change

Habitat Loss the greatest threat to biodiversity human population growth is the major factor disrupting ecosystems development (roads, communities) obtaining natural resources (lumber, coal, minerals) eastern cougar have become extinct - require a large territory marine habitats have been destroyed by deep sea trawling - dragging nets along the ocean floor - destroys coral beds (home to lots of organims solution? sustainable forestry sustainable fishing

Invasive Species non-native species that harm ecosystems where they are introduced prey on native species or outcompete them for resources usually introduced by human intervention: kudzu vine (from Japan) -grows out of control emerald ash borer - kills ash trees purple loostrife - clogs wetland habitats dog-strangling vine - grows out of control zebra mussels: released from the ballast of giant ships into the great lakes grow out of control - some areas have > 1 million per square metre lower oxygen levels in the lakes

Dog Strangling Vine Vincetoxicum nigrum

Kudzu Vine

Pollution burning coal - is one of the worst releases CO 2 releases sulfur dioxide and mercury that contribute to acid rain to be used as fuel, coal is washed - releasing sludge containing many toxins. pesticides inadvertently harm other organisms. can harm other organisms in an ecosystem (bioaccumulation or bioamplification). cause sex changes in some species (frogs, fish).

Overexploitation humans harvest natural resources faster than they can be replaced Canadian Cod Fishery - between , the annual catch dropped from nearly 500,000 tons per year to 12,000 tons. the cod have never recovered. Other examples: fur trade - giant otter, chinchilla aquarium hobbyists - tropical fish novelty pets - snakes, reptiles horticulture - orchids

Climate Change many human activities contribute to the release of CO 2 into the air burning fossil fuels, clearing land of plants or trees, burning forests, raising livestock (cow farts), draining wetlands. Potential Effects: Disease OutbreaksInsects adapt to new environment and come into contact with humans - SARS, H1N1 Plant MigrationGrasslands move north, replacing forests Animal MigrationPolar bears move south looking for food Extreme WeatherIce storms, droughts, floods Increased CO 2 When CO 2 dissolves in water, it changes the pH. Water Quality and Availability Water becomes scarce in dry areas - eg. arizona

Conserving Biodiversity: ex-situ conservation - protecting species by removing them from their natural habitats (zoos run breeding programs for endangered species) in-situ conservation - protecting species in their natural habitats (restoration biology in conservation areas). What can you do? look at your ecological footprint FootPrints in the Sand – The Nature of Things sand?auto_load_clip=