Transcript ecosystem - Humble ISD

Human Impact
Biodiversity: Necessary for Healthy Ecosystems
1.Biodiversity: sum total of all the different species
found in an ecosystem
a.The greater the number of species in an
ecosystem, the healthier the ecosystem.
b.Organisms are sources of foods, medicines, and
materials for clothing and shelter
Destroying Habitats Threatens Biodiversity
Humans destroy habitats:
• Habitat loss- converting
ecosystems into
housing, shopping &
industrial areas
• Habitat fragmentationisolating populations
into smaller portions of
their habitat
• Habitat degradationpolluting habitat’s land,
water and air
Slide # 4
Other Threats to Biodiversity
• Over-hunting: reduces population of
the species; can cause extinction
• Deforestation: bulldozing forests for
agriculture and human
developments
• Introduced / invasive species: new
species brought to an ecosystems
– Problem: no native predators;
they out-compete native species
for resources
– EX: Fire ants & zebra mussels
Introduced in 1930’s in
Port of Mobil, AL
Introduced in 1988
through the Great Lakes
The Spread of an Invasive Species
Slide # 6
Pollution: The Biggest Threat to Biodiversity
1.Pollutants damage / destroy
abiotic factors in ecosystems
a.Hard to get pollutants out of
air & water
b.Eventually destroys living
things
2.Hard to rebuild destroyed
ecosystems
3.Pollution prevention is the best
method to keeping ecosystems
healthy
Slide # 7
Eutrophication: Pollution in Waterways
1. Eutrophication: enrichment of
a lake / pond by N or P
a. Rate is increased by
fertilizer runoff & sewage
discharge
b. Algae have plenty of
nutrients & reproduce
rapidly
c. Algae die & are
decomposed by bacteria
d. Decomposing bacteria
consume all O2 in water
e. Fish die b/c there is not
enough O2 in water
Slide # 8
The Formation of Acid Rain
Emissions to Atmosphere
Nitrogen oxides
Sulfur dioxide
Chemical Transformation
Nitric acid
Sulfuric acid
Condensation
Dry Fallout
particulates, gases
Industry
Transportation
Ore smelting
Power generation
1. Acid rain lowers the pH of water & soil
2. Ca & Mg (essential nutrients) become less
available at low pH (acidic)
3. Al & Fe (toxic) become more available at
low pH & can kill plants
Go to
Section:
Precipitation
Acid rain, fog,
snow, and mist
Slide # 9
Damage from Acid Rain
Where is the wildlife?
Entire lakes in Canada, northern New York, and New
England have already died as a result. Mountain forests
in Maine and Vermont are dying too due to the acid fog.
Slide # 10
Effects of Pollution on Species: Biomagnification
1.Biomagnification: increasing
concentration of harmful
chemicals in organisms at higher
levels in the food web
a.Chemicals usually fat soluble
– build up in body tissues
b.If organism is food source for
humans, then humans ingest
chemical when they eat the
organism
Slide # 11
Biomagnification Also Harms Wildlife
1.Some chemicals (DDT) are
not excreted after they are
ingested
2.DDT accumulates in body
tissues
3.DDT can cause harmful
effects to offspring
4.If egg shells are
weakened, they will break
during incubation
Egg of eagle; shell is weakened.
Egg will be destroyed in incubation.
Slide # 12
Pollution Destroys the Ozone Layer
1. Ozone layer in stratosphere
protects us against UVA &
UVB radiation
2. CFC’s (chlorofluorocarbons)
react with ozone (O3) can
create holes in ozone layer
• allows UV radiation
through stratosphere
• Causes Earth’s temp to
increase
• UV radiation can damage
DNA of organisms
CFC’s were developed in 1930s
and used in a variety of industrial,
commercial, and household
applications. They are non-toxic,
non-flammable, and non-reactive
with other chemical compounds.
In 1973 we learned that chlorine
accelerates ozone destruction
Slide # 16
Reducing the Human Impact
1. Protection of endangered species – (when an
animal or plant species becomes so rare that it is
threatened with extinction).
2. Conservation involves managing renewable
resources so that they will still be available in the
future (freshwater, soil, forest, wildlife and fishery
resources).
3. Pollution Prevention- is the best way to prevent
damage to ecosystems.