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Man’s Impact on the Environment

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Presentation on theme: "Man’s Impact on the Environment"— Presentation transcript:

1 Man’s Impact on the Environment

2 Threats to Biodiversity
Biodiversity has three components: Genetic diversity. This is the pool of genetic information and variations found in the biosphere. Species diversity – The number of different life-forms found on the planet. Almost 2 million species have been described to date. Ecosystem diversity – The unique assemblages of interact communities scattered around the globe. When populations are reduced and/or species become extinct, genetic information is lost forever without us ever knowing its potential benefit to both that species, and to mankind. There is a list of threatened and endangered species (both in the U.S. and worldwide). At present 24% of mammalian species are endangered and approximately 20% of freshwater fish have gone extinct or are threatened with extinction. Many plants , insects, and other invertebrates are also imperiled. Coral reef and tropical forest ecosystems have been and are being seriously impacted by man’s activities. In the late 1990’s, illegal wild fires, that were set to clear rainforest in Borneo, caused so much severe air pollution in Singapore, Malaysia, and the surrounding region that the governments of those countries called a regional conference to address the issue.

3 Importance of biodiversity
Plants , microbes, and animals contain a vast genetic diversity that may in the future provide many needed products for mankind. About 25% of all pharmaceuticals contain chemicals derived from plants. Many companies are ‘bioprospecting’ for useful enzymes and drugs. They do this by screening for useful enzymes in microbes that live in unusual or extreme habitats, by looking for cancer fighting chemical in marine invertebrates (sponges don’t get cancer), or by searching tropical forests for potential pharmaceuticals. Healthy ecosystems controls runoff and erosion. They can absorb excess nutrients before they cause europhication. They provide the pollinators needed for agricultural crops, and provide organisms for the biological control of agricultural pests. We don’t know what future discoveries can improve our lives, but we do know that this won’t happen if we lose the biodiversity upon which it depends.

4 Exotic plants in South Florida
South Florida has many invasive exotic plants which dominant and/or overrun native plant communities. Miami-Dade County’s Department of Environmental Resource Management (DERM) has a long list of plants that are forbidden to sell or plant in South Florida. The picture to the right shows Burma Reed, a large (10-12 ft. high) invasive grass, in front of a thicket of Brazilian pepper (Schinus). Three problem species can be seen on the next page.

5 Exotic plants in South Florida (left) air potato – who needs Kudzu
Exotic plants in South Florida (left) air potato – who needs Kudzu!, (upper right) castor bean – seeds are toxic, (lower right) Brazilian pepper – related to poison ivy, red fruit spread by birds.

6 Exotic animals in South Florida
More than 30 lizards and 3 species of exotic snakes are established in Florida (most can be found in South Florida. The number increases every year. The Tokay gecko (right) is large (10-12 inches), vocal, and common in South Dade. There are 63 species of introduced fish in the South Florida drainage basin. The peacock bass from northern South America (right) was introduced by state fisheries biologists to attempt control of tilapia populations. Local tilapia species are native to parts of Africa.

7 Chemical pollution in the environment
Biological magnification is the reason that species at the top of the food chain are more toxic than those at lower trophic levels. Compounds, such as DDT and PCBs, have in the past and are presently causing environmental problems. On the next page there is an illustration of biological magnification. Oil spills can destroy or disrupt local coastal ecosystems and/or communities. Loss of large parts of the ozone layer have been attributed to the use of chlorofluorocarbons in aerosol cans. That is way these compounds have been banned in air-conditioners and refrigeration units Mercury is a naturally-occurring toxic trace element which has a complex cycle between the Earth’s crust, atmosphere and oceans. Some mercury is released by natural processes but the predominant emissions to the atmosphere result from human activities Mercury deposited in wetlands, lakes and streams can be converted by natural bacteria into methylmercury, a toxic form that is accumulated and biomagnified at each link in the food chain. In some circumstances, the result is sport fish that would be toxic if eaten by humans and prey fish that may be toxic to wildlife that eat them.

8 Chemical Pollution Eutrophication, caused by the runoff of nitrates and other nutrients from the land, has created large areas that are devoid of oxygen. There is a major dead zone in the Gulf of Mexico off the Mississippi River Delta. Sea areas starved of oxygen will soon damage fish stocks even more than unsustainable catches, the United Nations believes. (BBC News Monday, 29 March, 2004) .

9 Global warming Virtually all atmospheric scientists believe that the evidence for global warming is overwhelming. Many politicians are reluctant to accept this evidence, because it means that something REALLY must be done to limit greenhouse gas emissions. Part of the rise in global temperature may be due to long term atmospheric cycles, however man’s activities have probably been the major contributing factor. The data below was collected at Mauna Loa, Hawaii.

10 Global warming The greenhouse effect is shown in the illustration below. An average temperature rise of only a few degrees (Celsius or Fahrenheit!) can lead to significant sea level rise and altered rainfall pattern. The real problem is that if we wait too long to control green house gases, it may take a long time to see positive change. It’s like trying to stop a freight train when there is a truck on the track ahead. You can hit the brakes when the train is 200 yards away from the truck, but it won’t stop for another ½ mile!

11 Critical habitat Critical habitat is the set of environmental conditions necessary to maintain a species. It may be mature long-leaf pine forests for the red-cockaded woodpecker, or old growth forests for the northern spotted owl. It is necessary to determine the habitat needs of a species, before a management plan can be developed. Since not every species can be saved, it is also important to determine the keystone species in order to best protect the overall community structure.

12 Landscape ecology and movement corridors
A goal of landscape ecology is to study human land use patterns and make biodiversity conservation a priority. When habitats are fragmented by human development is sometimes possible to develop movement corridors to connect pieces of high quality habitat. These may spans distances of many miles or they may be local man-made corridors to protect wildlife. To the right is an animal bridge in Braniff National Park, Canada, however you don’t need to go to Canada to see movement corridors. Drive across Alligator Alley (I-75) between Ft. Lauderdale and Naples and look the edge of the road. The whole road is fenced to prevent animals from being killed while crossing the highway. Periodically there are bridges, with animal corridors beneath, which allow deer, Florida panther, raccoons, and other animals to cross from north to south without risk of being hit by traffic.

13 Protected Areas Not everything can be protected, so scientists are focusing on protecting biodiversity hotspots. These are small areas that have a relatively high number of species. Hotspots can be seen in purple on the map below. Because of their great diversity, these hotspots are also at great risk from development. Fisheries biologists are using NO FISH zones to protect breeding stocks, and nursery grounds. A large no-fish zone has been established in the waters near Dry Tortugas National Park, and a no-fish zone exists in Merritt Sound by Cape Canaveral.

14 Restoration ecology The goal of restoration ecology is to develop ways to return degraded ecosystems to conditions as similar as possible to their natural, predegraded state. These techniques have been used to bring spawning salmon back into rivers and streams where they once bred. Controlled burns are sometimes used (see the illustration lower right). Bioremediation uses plants and microbes to remove toxic chemicals for polluted areas. This has been used successfully to help clean-up oil spills. The on-going Everglades Restoration Project is one of the largest restoration projects ever attempted, and is still many years from completion.

15 Kissimmee River project
The Kissimmee River runs from the lakes of central Florida to the northern edge of Lake Okeechobee. It was a meandering river full of ox-bow bends. Water moved slowly. Too slowly for man. A plan was developed and implemented to channelize the river. (see lower right). Now the river ran straight and fast. Unfortunately it also now dumped huge amounts of nutrients into Lake Okeechobee, triggering vast algal blooms that threatened the health of the lake. This lead to the Kissimmee River Restoration Project. The goal was to un-channelize the river and reestablish its meandering nature. This would slow water flow and allow nutrients to be filtered out, before the water entered Lake Okeechobee. So far the project has been very successful in reducing the nutrient load into the lake. This is an example of how restoration efforts can reverse environmental damage

16 Zoned reserves Zoned reserves are protected areas that are surrounded by zones in which there is human habitation, but the land is protected from extensive alteration. Costa Rica has used the concept of zoned reserves to protect much of its biologically diverse land. The government and people of Costa Rica should be commended for their attempts to both manage their rich biological resources, and work towards a plan for sustainable development. Hopefully more countries will follow their example.

17 Sustainable development
Our goal should be sustainable development. Both using and protecting resources in such a manner that they are available to the generations that come after us. Sustainable development will depend not only on continued research and application of ecological knowledge. It will also require us to connect the life sciences with the social sciences, economics, and humanities. Conservation and restoration of diversity is only on side of sustainable development; the other key facet is improving the human condition. Public commitment and cooperation of nations are essential to the success of this endeavor. Each of us must play our part, no matter how small, if this is to become a reality.

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