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ECOLOGY
HUMAN INFLUENCES
TOPICS
1. Biosphere Issues
a.
b.
c.
Global Warming
CFCs
UV Radiation
2. Ecosystem Issues
a.
b.
c.
Biomagnification
Biodiversity Loss
Alien Species
3. Conclusion
a.
b.
Precautionary Principle
Local change
THE GREENHOUSE EFFECT
BIOSPHERE ISSUES
GLOBAL WARMING
• Video
• Case Study
THE LAYERS OF
THE
ATMOSPHERE
The troposphere is the part of the
atmosphere in the biosphere
The stratosphere contains the
ozone layer
The stratosphere is also a zone of
warm air that keeps a lid on the
troposphere. It does not mix with
the upper atmosphere
© Text 2007 Paul Billiet ODWS
© Windows to the Universe
THE OZONE LAYER
SUNLIGHT
ENERGY IN THE
ATMOSPHERE
© Windows to the Universe
CHLOROFLUOROCARBONS (CFCS)
THE OZONE LAYER STOPS 99% OF
UV RADIATION
OZONE
BIOSPHERE ISSUES
CFCS
• CFCs are chlorofluorocarbons
• These are molecules used in:
• Refrigerators
• Air conditioners
• Fire extinguishers
• Propellants in aerosol sprays
BIOSPHERE ISSUES
CFCS
• It was believed that they diffused harmlessly into the
stratosphere where they were broken down by
sunlight.
• This is true, BUT…
• We now know that in the process of breaking them
down, a chlorine atom is produced.
• Chlorine is very destructive to the ozone layer.
• Chlorine reacts with ozone molecules and breaks it
apart into oxygen, which cannot turn back into
ozone.
• One chlorine atom can destroy 100,000 ozone
molecules.
THE EFFECTS OF UV RADIATION
• The main effect of UV radiation on living tissues is its
ability to alter DNA.
• This can eventually lead to skin cancer.
SPECIFIC EFFECTS
• Skin cancers
• Carcinomas (relatively minor)
• Melanomas (dangerous)
• Eye issues
• Cataracts (lens becomes less transparent)
• Growths
• Phytoplankton – very sensitive to UV light
• Plants – lower crop yields
• Nitrogen-fixing bacteria – low tolerance to UV light
THINK, PAIR, SHARE
a. Are CFCs that big of a
problem? Why or why
not?
b. Propose a solution to
this problem.
TOPICS
1. Biosphere Issues
a.
b.
c.
Global Warming
CFCs
UV Radiation
2. Ecosystem Issues
a.
b.
c.
Biomagnification
Alien Species
Biodiversity Loss
3. Conclusion
a.
b.
Precautionary Principle
Local change
BIOMAGNIFICATION
• Another side-effect of our
contaminating the environment is
biomagnification.
• Once toxins are in the environment,
they can be ingested or absorbed
into organisms.
• If an organism takes in small
quantities of a toxin without breaking
it down or excreting it, it
accumulates in its body. This is
called bioaccumulation.
BIOMAGNIFICATION
• As these toxins travel up
the food chain, they
become more
concentrated at each
trophic level. This is called
biomagnification.
EXAMPLE - DDT
• DDT is the best known organic
pesticide (it was used to kill
insects).
EXAMPLE - DDT
•
•
•
•
It is hydrophobic, so it won’t dissolve in water.
This means it stays where its sprayed for a long time.
This also means that it cannot be excreted in urine.
It takes 2-15 years for it to break down.
DDT IN A FOODCHAIN
TEXTBOOK EXAMPLE
P. 1202-1203
1. Read the section entitled, “Toxins in the
Environment”
2. Make a sequence of events chart to show the
progression of DDT in the environment.
DATA-BASED QUESTIONS
CLOSURE
• “Man has lost the capacity to
foresee and to forestall. He will
end by destroying the earth.”
• Albert Schweitzer
INVASIVE SPECIES
• Invasive (alien) species are nonnative, introduced species that
affect native organisms, change
ecosystems, and cause lots of
damage!
• They get introduced into an
ecosystem, either intentionally or
accidentally.
• They thrive to the detriment of other
species.
The Cane Toad
HUMAN INFLUENCES IN ECOLOGY
TOPICS
1. Biosphere Issues
a.
b.
c.
Global Warming
CFCs
UV Radiation
2. Ecosystem Issues
a.
b.
c.
Biomagnification
Alien Species
Biodiversity Loss
3. Conclusion
a.
b.
Precautionary Principle
Local change
BIODIVERSITY
1. What is biodiversity?
2. How is biodiversity calculated?
3. Causes of Biodiversity Loss
4. Reasons for Conservation
BIODIVERSITY
• Biodiversity refers to the
variety of life on Earth.
• It includes:
• the variety of species
• the genetic variations within
species
• the different types of
ecosystems and biomes the
species live within.
• Definition of species?
• A group of organisms that
can interbreed and produce
fertile offspring.
BIODIVERSITY BY THE NUMBERS
• The reported number of
species on the planet varies
widely.
• Traditionally the number is
somewhere between 5 and
30 million.
• Approximately 1.75 million
species have been formally
described and given official
names.
NUMBER OF DESCRIBED SPECIES ON
EARTH
•
•
•
•
•
•
•
•
•
Species
Bacteria
Protists (algae, protozoa)
Animals – vertebrates
Animals – invertebrates
Fungi
Plants
Number
4,000
80,000
52,000
1,272,000
72,000
270,000
Total described species
1,750,000
• Source: UNEP/Global Environment Outlook (Ref 3)
• Insects comprise more than half of all known
species on the planet!
HOW DO WE CALCULATE
BIODIVERSITY?
• Before biodiversity is calculated, populations must
be counted.
• How are populations counted?
• We would take samples!
• Quadrant Sample
• Transect Line Sample
HOW DO WE CALCULATE
BIODIVERSITY?
• Once population density is determined…
• Scientists calculate diversity by using the Simpson
diversity formula.
• It takes into account the number of different
species within the community and the number
within each species.
• Definition of community?
• A group of different populations in the
same area.
SIMPSON DIVERSITY FORMULA
D=
N = the total number of organisms of all species
n = the number of organisms of a particular species
D = the diversity index
The value of D represents how diverse a community is.
The higher the number, the more diverse an area is.
G.3.1 CALCULATE THE SIMPSON
DIVERSITY INDEX
BIODIVERSITY LOSS
• Biodiversity is being influenced by humans.
WITH YOUR PARTNER
• Come up with 3 specific humaninduced causes of loss of
biodiversity.
What’s causing loss of biodiversity?
1. Overexploitation (over hunting, clearing of forests)
What’s causing loss of biodiversity?
2. Habitat Destruction
What’s causing loss of biodiversity?
3. Introduction of alien species
What’s causing loss of biodiversity?
4. Pollution
What’s causing loss of biodiversity?
5. Climate change
With your table partner, discuss…
• Come up with 2 reasons why
biodiversity should be conserved?
• Most people think the MAIN reason why biodiversity
should be conserved is just for “beauty” reasons.
However….there are other important reasons too!
REASONS FOR CONSERVATION OF
BIODIVERSITY
1. Ethical Reasons
All life has value.
Destroying ecosystems denies future generations.
“Extinction is forever”
We are not the only ones here.
REASONS FOR CONSERVATION OF
BIODIVERSITY
2. Ecological Reasons
•
•
A loss of biodiversity will affect ecosystems.
• Food webs will be altered.
• The effects will have a domino effect.
• The recycling of nutrients will be altered.
Tropical rain forests cover about 7% of the Earth’s
land surface, but they contain more than 50% of
the known species.
REASONS FOR CONSERVATION OF
BIODIVERSITY
3. Economical Reasons
•
Food sources
•
Pharmaceutical companies are continually
researching new medicines from wild species.
•
Some countries depend on their “wildlife” to
attract tourists.
REASONS FOR CONSERVATION OF
BIODIVERSITY
4. Aesthetic Reasons
CLOSURE
Please fill out the Exit Ticket
a.Define biodiversity.
b.Name two reasons why we should conserve
biodiversity.
c.If we continue consuming paper products at our
current rate, the rainforest will be extinguished in 120
years. Are you willing to sacrifice your “need” for
paper products in order to conserve biodiversity in
the rainforest? Explain your thinking.
BELLWORK
What are two ways that
scientists take samples of
populations?
Hint: Think of the “mini-lab” we
did outside. 