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Man’s Impact on the Environment

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Title: Man’s Impact on the Environment


1
Mans 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 mans
    activities. In the late 1990s, 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 dont 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 dont know what future discoveries can improve
    our lives, but we do know that this wont 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 Countys 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!, (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
    Earths 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 mans
    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. Its 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 wont 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 dont 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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