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.

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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.

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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.
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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.
  

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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) .

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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!

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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.

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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.

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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.

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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

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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.

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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.