Unit 4: Biodiversity and Endangered Species Section 2: Threats to Earth’s Diversity
Central Case Study: Will we slice through the Serengeti? Serengeti National Park – Located on the border of Tanzania and Kenya (East Africa) Comprised of dry, temperate grasslands and savanna biomes Hosts over 800,000 visitors per year = $3 Billion to local communities (major economic factor) Tanzania’s government plans to build a highway through park Issues: Will cut off yearly migration paths for wildebeest, zebras, etc. Could encourage poaching by giving easier access to animals Currently on hold but growing support again for this highway
Benefits of Biodiversity Provide ecosystem services Help maintain ecosystem function Enhance food security Provide drugs and medicines for human use Boost economies through tourism and recreation The value of ecosystem services = $48 trillion per year!!!!!! Biodiversity
All Good Things Come to an End Extinction is a natural process Populations can die out (extirpation) without the entire species dying Species go extinct naturally all the time This is known as the background rate of extinction However, current extinction rate is 100 to 1000 times faster than background rate Other extinctions are brought on by human activity #1 Cause of Loss of Biodiversity and Endangerment: Habitat loss and fragmentation (deforestation, pollution, etc.) Housing developments, farming, damming rivers, domestic grazing Overharvesting
Extinct Species: Dodo bird, Carolina parakeet, passenger pigeon, Great Auk, Tazmanian Tiger
It Ain’t Just a New Thing Polynesians caused large extinctions of birds when they arrived in places like Hawai’i and New Zealand Large mammals were decimated in North America and Australia with the arrival of indigenous people
Endangered and Threatened Species: Ecological Smoke Alarms Endangered species: so few individual survivors that it could soon become extinct. Threatened species: still abundant in its natural range but is likely to become endangered in the near future.
Figure 11.3 Endangered natural capital: species that are endangered or threatened with premature extinction largely because of human activities. Almost 30,000 of the world’s species and 1,260 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger.
Endangerment can Lead to Extinction Some species are more at risk than others. Certain characteristics cause this… Low Reproductive Rate Specialized Feeding Habits Feed at high trophic levels Large size (easy targets/slow movement) Specialized nesting or breeding areas Found only in one place or region (endemic) Fixed migratory patterns Preys on livestock or people Behavioral Patterns
Biodiversity is decreasing unequally Percentage of various species types threatened with premature extinction from human activities.
IUCN’s Red List International Union for Conservation of Nature (IUCN) annually puts out the Red List to list species at risk of extinction
Living Planet Index
Threats to Biodiversity Conservation biologists summarize the most significant causes of premature extinction as “HIPPO”: Habitat destruction, degradation, and fragmentation Invasive species Population growth (Human) Pollution Overharvesting An actual Hippo… which is also classified as vulnerable…
Invasive Species Examples to know: Zebra Mussel (Great Lakes) Organisms that have been intentionally or accidentally introduced into an area that they are not native to Examples to know: Zebra Mussel (Great Lakes) Brown tree snake (Guam) Kudzu (Southeast US) Cane Toads (Australia) Asian Carp (Mississippi Valley)
Overexploitation Overharvesting for… Food Decoration Medicine Many of these items are obtained through poaching and are sold illegally on the black market Bushmeat Ivory Pelts/Fur
Climate Change’s Effects Impacts on the Earth’s climate system are global Extreme weather events (storms) increase stress Melting sea ice in the Arctic threatens polar bears Mountaintop species are losing their habitat A 1.5–2.5C temperature rise could put 20%–30% of plants and animals at increased risk of extinction
What are we doing to fix it? Conservation Biologists are studying ways to save much of Earth’s biodiversity Environmental Legislation: ****Endangered Species Act (ESA)**** – United States; enacted in 1973; forbids government and citizens from taking any actions that destroy endangered species or their habitats 2013: 1118 U.S. species endangered; 322 threatened Most Notable Success Story: Bald Eagle; population recovering after ban of DDT in 1973; 2007 – Removed from Endangered Species List
What are we doing to fix it? Environmental Legislation: Species at Risk Act – Canada; enacted in 2002; scientists have argued that it is too weak and does not protect habitats adequately ****Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)**** - United Nations (169 countries); treaty formulated in 1973; protects endangered species by banning international trade of their body parts Convention on Biological Diversity – numerous nations; 1992; goals – to conserve biodiversity, use biodiversity sustainably, ensure fair distribution of benefits; helped nations gain economic benefits from ecotourism; Treaty’s overall goal was not met by 2010
In-situ Conservation Leaving the animal where it lives but protecting it. Ex. Elephants; make laws that prevent poaching and have people to enforce it Ex. Marine turtles are protected - escape nets must be used on all fishing nets so the turtles can get out and not drown
Ex-situ Conservation Taking the animal out of its habitat & protecting it. Ex. Zoo’s 2 types: Captive breeding Reintroduction programs Cloning
Habitat restoration Focus on hotspots Restoration - Research and scientific study devoted to restoring, repairing, and reconstructing damaged ecosystems. Preservation - Setting aside or protecting undisturbed natural areas from harmful human activities. National parks and reserves Remediation - Repairing an ecosystem that has been destroyed. Remove pollution from ecosystem Mitigation – create new ecosystems to offset known impacts on existing ecosystems