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G3:
Impacts of Humans
on Ecosystems
(6 hours)
G.3.1 Calculate the Simpson diversity index for two
local communities.
• D = diversity index
• N = total number of organisms of all species found
• n = number of individuals of a particular species
• D = [N(N-1)] / [sum of n (n-1)]
• Have to record total # of individuals & # of each
species
• Example…
Sample two dune communities:
Plant species
n
n(n-1)
3(2)=6
Plant species n
n(n-1)
Oak tree
3
Marram grass 50
50(49)=2450
Hickory tree
1
Milkweed
10
Maple tree
1
Poison ivy
10
Beech tree
1
Sand cress
4
Fern
5
Rose
1
Moss
3
Sand cherry
3
Columbine
3
Totals
N=78 2648
Trillium
3
Virginia creeper
4
Solomon seal
3
Totals
N=27 62
G.3.2 Analyse the biodiversity of the two local
communities using the Simpson index.
Calculate D!!
• Foredune
D = 78(77)/2648
= 2.27
• Mature dune
D = 27(26)/62
= 11.3
More diverse, although total plant #s is less!!!
Higher # of diff. species
Sample it periodically...health of ecosystem!
G.3.3 Discuss reasons for the conservation of
biodiversity using rainforests as an example. Reasons
should include ethical, ecological, economic aesthetic
arguments.
• Aim 8: There are environmental issues affecting
the whole planet and also ethical issues involved
in conservation that could be raised here.
• PLANET EARTH VIDEO...IMAGINE YOURSELF
THERE...
• Rain forest example...
Reasons to Conserve the Rain Forest
• Economic
– Most nutrients in plants, not in soil
– Logging  nutrient-poor soil
– Sources of medicines, chemicals...could go extinct
– Ecotourism
• Ecological
– Keystone species may be lost
– All species of ecosystem interdependent
– Invasives – if low diversity, less likely to sustain pressures
– Plants are CO2 sink, remove it from atmosphere...global warming.
– Soil erosion, flooding
• Ethical
– Local human populations!
– Help them make a living from it while preserving it
– Ethical responsibility to conserve it for future generations, reduce human
impact, increase education/awareness
• Aesthetic
– Ecotourism, boosts human well-being
– Inspiration for artists, writers, photographers, ...
G.3.4 List three examples of the introduction of alien
species that have had significant impacts on
ecosystems.
• accidental release of invasive species
– Zebra mussels, 1980s, maybe from ballast water to US/Lakes
– Clog pipes (factories, etc)
– High repro. Rate, so overgrow quickly
– Is filtering water of Lake Michigan very well….good or bad??!?!?!
More light, more growth of plants, may be better habitat for fish…or
not.
– $500 billion in next 10 years!
• deliberate release of invasive species
– Kudzu, from Japan to US 1876 (ornamental plant); 1930s
promoted for soil conservation by govt
– 1953-Dept Ag: It’s a pest weed!
– Common in SE, grows quick, horiz. And vert.; US loses $500
million annually b/c of it
G.3.4 List three examples of the introduction of alien
species that have had significant impacts on
ecosystems.
• biological control
– Prickly pear cactus, Australia, 1800s introduced
on purpose
– 1900s spreading too quickly
– Research…how to control it biologically?
– MOTH feeds on it…introduce moth to Aust.
– Currently in balance
• xref- precautionary principle-5.2.4
G.3.5 Discuss the impacts of alien species on
ecosystems.
Named examples of each:
• Inter-specific competition
– Red squirrel (UK): grey squirrel (US) introduced to UK 1800s,
outcompeting, pushing out of habitat. Now, RED only occurs
where grey not inhabiting. No documented damage...yet.
• Predation
– St. Lawrence Seaway allowed ocean fish to travel to fresh
water
– Sea lampreys invaded area, preyed on lake trout, pop
declined; lamprey then preyed on whitefish...their pop
declined
– Introduced salmon to replace whitefish and trout in L.Michigan
– Sought-after gamefish (tourist $$$), eats small ocean-fish
invasives
G.3.5 Discuss the impacts of alien species on
ecosystems.
Named examples of each:
• Species extinction
– Lake Victoria-80% cichlids
– 1950s-overfishing
– Introduced Nile Perch to increase pops
– 1970...cichlids only 1%! (200 of the 400
cichlid species now extinct b/c competition)
– “benefit” for fishermen; “bad” for diversity
G.3.6 Outline one example of biological control of
invasive species.
•
Aim 8: Invasive alien species are such a widespread problem that it will
almost certainly be possible to find a good local example. Such species are a
real threat to the biodiversity of the planet, with many species facing extinction
as a result. The uniqueness and cultural diversity of human populations are
also being affected.
• Biological control of pest species
– Natural predator to control unwanted/invasives
– Always a risk!!
– Purple loosestrife: threat to native wetland plants;
beetles used to control b/c larvae feed on plant
– Red fire ants: introduced from SAmer., outcompete
native ants (and OUCH!!!); phorid fly injects eggs
into ant...larvae eat way to head and decapitate it!!!
Current research...Gainesville, FL.
G.3.7 Define biomagnification.
• process in which chemical substances become
more concentrated at each trophic level
G.3.8 Explain the cause and consequences of
biomagnification, using a named example.
• Fat soluble chemicals work up the food chain!
– Xref- food chains - 5.1.4
• organophosphorus pesticides: DDT
– Mosquito control (didn’t know it persists decades)
– Into water, plankton, fishes, …
– Birds accumulate the highest levels
– Egg shells weak/less Ca; offspring mortality
• mercury in fish
– Air pollution (factories, etc.)
Hmmmm...
• Developed countries pressure undeveloped
countries to ban use of DDT
• Mosquitoes are vector for malaria
• Not using DDT has caused increase in malaria
incidence
• Do YOU think DDT should be allowed here or
not?
G.3.9 Outline the effects of ultraviolet (UV) radiation on
living tissues and biological productivity.
• Non-lethal skin cancer (basal, squamous cell
carcinomas—decrease of 1% ozone  increase cancers
2%!
• Lethal skin cancer (malignant melanoma; 15-20% cases
are lethal… early detection key!)
• Mutation of DNA
– Xref- DNA structure- 3.3.4/7.1
• Sunburn (enlarged blood vessels…some epidermal cells
die, peel off) ewww!
• Cataracts (clouding of lens, vision loss) SUNGLASSES!!!
• Biological productivity reduced b/c plant loss (less
photosynthesis, mutate plant DNA, phytoplankton &
aquatic food chains! YIKES!
G.3.10 Outline the effect of chlorofluorocarbons (CFCs)
on the ozone layer.
• Ozone protects from UV
• Forms in stratosphere when O2 breaks apart and combines with
another O – constantly being formed, broken down, and reformed
• 1985: CFCs are thinning it (~20km thick)
– Int’l: Montreal Agreement to phase out use
– Fridge coolants
– Aerosol propellants
– Foam packing manufacture
• CFCs break down, release Cl– O3 + Cl-  ClO + O2
– ClO + O  Cl- + O2
– Free Cl- breaks down another O3...1 CFC molecule can move to
stratosphere in 15 yrs, remains there destroying ozone for a
century! 
G.3.11 State that ozone in the stratosphere absorbs UV
radiation.
• There is a limit to UV absorption in the
stratosphere.
• There is no need to mention UV-A, UV-B and UVC.
Group IV Project: Wed. April 6th
• 2nd graders
• Small groups, small lessons/demos/activities
• They learn about: all the animal groups—insects,
birds, plants (1st grade)
– Life cycle stuff
– Predators and prey
• WHAT DO YOU WANT TO DO?!?!
– Game/activity/skit/demo
– YOU are INDIVIDUALLY GRADED…everyone must
be ACTIVELY involved in all steps…