Download G.3 Impact of humans on ecosystem

G.3 Impact of humans
on ecosystem
I B BI O I I
VAN ROE KE L
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G.3 Assessment Statements
G.3.1 Calculate the Simpson Diversity index for two local communities
G.3.2 Analyze the biodiversity of the two local communities using the Simpson index
G.3.3 Discuss reasons for the conservation of biodiversity using rainforests as an example
G.3.4 List three examples of the introduction of alien species that have had significant impacts on ecosystems
G.3.5 Discuss the impacts of alien species on ecosystems
G.3.6 Outline one example of biological control of invasive species
G.3.7 Define Biomagnification
G.3.8 Explain the cause and consequences of biomagnification using a named example
G.3.9 Outline the effects of ultraviolet (UV) radiation on living tissues and biological productivity
G.3.10 Outline the effect of chlorofluorcarbons (CFCs) on the ozone layer
G.3.11 State that ozone in the stratosphere absorbs UV radiation
Simpson Diversity index
Biological diversity described in two ways:
◦ Richness: number of different organisms in a
particular area
◦ Evenness: how the quantity of each different
organism compares with the other
Simpson Diversity Index measures the
diversity of a given area at a given time, taking
into account the evenness and richness of the
area.
Simpson Diversity Index
In order to find diversity of a community, must use random sampling
(Quadrat Method) to sample two dunes
◦ Record number of plant species in each quadrat
◦ Count number of individuals of each species
◦ Record the data for each area
Uses:
◦ Species richness – higher the score, the greater the diversity = shows a
healthy habitat
◦ Dominance – the lower the score, the more the area is dominated by one
species, or the area is under environmental stress
◦ Stability – consistent scores over a period of time suggests a stable local
environment
Simpson Diversity Index - Foredune
Plant Species
# of individuals, n
n(n-1)
Marram Grass
50
50(49) = 2450
Milkweed
10
10(9) = 90
Poison Ivy
10
10(9) = 90
Sand Cress
4
4(3) = 12
Rose
1
1(0) = 0
Sand Cherry
3
3(2) = 6
Totals
N = 78
2648
Simpson Diversity Index – Mature dune
Plant Species
# of individuals, n
n(n-1)
Oak Tree
3
3(2) = 6
Hickory Tree
1
1(0) = 0
Maple Tree
1
1(0) = 0
Beech Tree
1
1(0) = 0
Fern
5
5(4) = 20
Moss
3
3(2) = 6
Columbine
3
3(2) = 6
Trillium
3
3(2) = 6
Virginia Creeper
4
4(3) = 12
Solomon seal
3
3(2) = 6
Totals
N = 27
62
Simpson Diversity Index - Dunes
Foredune:
D = 78(77) / 2648
D = 2.27
Mature Dune:
D = 27(26)/62
D = 11.3
Reasons for Conservation of Biodiversty
Economic:
◦ Ecotourism – local income
◦ Useful or new medicines/materials can be found in plants
◦ Protecting future generations
Ecological:
◦ Species are interdependent – loss of one can impact others
◦ Diversity protects against invading species (more competition)
◦ Deforestation  soil erosion/flooding/drought
◦ More plants to remove CO2 from atmosphere
Reasons for Conservation of Biodiversty
Ethical:
◦ Protecting future generations
◦ Cultural importance to indigenous groups
◦ Role as keepers of the land/protecting intrinsic value
Aesthetic:
◦ Human appreciation of exotic species
◦ Ecotourism – local income
Introduction of Alien Species
Alien species – one which arrives in a
non-native habitat, usually as the
intentional or accidental result of
human activity.
Some alien species are very successful
in the new habitat and out-compete
native species, causing ecological and
economical damage
Introduction of Alien Specie - Examples
Kudzu – plant introduced to the U.S. from
Japan in 1876
Promoted by Soil Conservation Service as a
fast growing plant that could solve problem
of soil erosion
1953 – recognized as a pest weed because it
grows so fast (20 meters per growing
season)
Thick growth of plant crushes other plants as
it covers them, and can break branches of
trees because of weight.
Introduction of Alien Specie - Examples
Zebra Mussels: tiny, black and white striped
mollusks that invaded North America in 1980s by
cargo boats
Spread all over the great lakes and are estimated
to spread all over the US and Canada. 1 zebra
mussel can release up to 100,000 eggs per year.
Clog pipes that transport surface waters to utility
plants, factories, etc., as mussels bind to and build
on each other
Estimated cost on zebra mussels is $500 billion in
next 10 years
Causing waters of lake Michigan to be very clear –
resulting outcome is unknown
Introduction of Alien Specie - Examples
Cane Toads – introduced to Australia to
control agricultural crop pests on sugar cane
Now classified as invasive species because
of rapid and multiple reproductions
Toxic secretion and skin is threatening to
other animals and even humans that come
into contact with it.
Australians are encouraged to kill cane
toads when they seem them by putting
them in a bag in the freezer
Impact of alien species on ecosystem
Interspecific competition: alien species out-competes native species for
resources such as food, space, or light. Native species may be forced out of
niche (Kudzu, zebra mussels)
Predation: Aliens can be predators to other native species. Prey species decline
rapidly as they cannot adapt to new predator (cane toads)
Species extinction: Native species can be out-competed to the point of
extinction, or extinction can occur due to hybridization, or the “pollution” of the
native species gene pool, replacing it with a newly formed species
Biological Control of Alien Species
Biological Control is the idea of using a natural predator to control an
unwanted or invasive species
Example:
◦ Purple loosestrife is an aggressive invasive plant that can displace native
wetland plants in the U.S. and Canada
◦ Several states have been given permission to introduce two beetles
(species of Gallerucella) as biological control agents
◦ Adult beetles feed on leaves of purple loosestrife
◦ Larvae feed on the leaves and stem of the plant
◦ Goal is to reduce the number of purple loosestrife in the environment
Biomagnification
Biomagnification: a process by which chemical substances become
more concentrated at each trophic level
Chemicals taken in by plants may not have an affect on plants
because of the small concentration
As consumers eat more plants with small concentration, their
chemical concentration increases
Chemicals are typically fat soluble, meaning they are stored in fatty
tissues of consumer, which is easily transferred.
Examples: DDT, dioxins, pesticides, and mercury
Biomagnification – Causes (DDT)
DDT is a pesticide that was used to control mosquitoes and other
pests
DDT does not break down and would persist for decades in an
environment
Eventually entered the water supply, where it was absorbed by
microscopic organisms, these were eaten by small fish, which were
eater by larger fish, which were eaten by birds
As DDT traveled up trophic levels, it became more concentrated in
fatty tissues of each consumer
Biomagnification – Consequences (DDT)
Decline in the number of predatory birds
◦ Reduced reproductive functions
◦ Eggs of birds were easily cracked
Eventually was found that DDT was building up in the tissue of birds
and interfering with the calcium needed for shell to harden
DDT was banned in U.S. in 1971
Ozone layer
Ozone layer is similar to
sunscreen for the planet.
Located in the stratosphere and
absorbs ultraviolet (UV)
radiation (93%)
◦ Found 15-35 km above Earth’s
atmosphere and is roughly 20 km
thick
Composed of ozone (O3), which is
formed when oxygen (02) breaks
down and binds with another
oxygen molecule
Ozone Layer and CFCs
Ozone Layer is depleting
Main cause of depletion is chlorofluorocarbons (CFCs)
◦ CFCs break down to release chloride ions
◦ Chloride ions react with ozone molecules and produce chlorine monoxide
(ClO) and oxygen (O2)
◦ ClO joins with O atom to form more O2 and release another chloride ion.
◦ Cycle can continue for a century
Montreal Protocol
◦ Adopted to phase out CFCs in refrigerator coolants, propellants for aerosols,
and materials used to make foam packaging.
Effects of UV Radiation
Human Health Impacts:
◦ Scientist have found that a decrease of 1% of stratospheric ozone increases these cancers by
2%
◦ Non-lethal skin cancer – Basal and squamous cell carcinoma are forms of non-lethal cancer.
◦ Lethal Skin Cancer – Malignant Melanoma is a form a skin cancer that is lethal in 15-20% of
cases.
◦ Cataracts – clouding of the lens of the eye, leading to loss of vision
Mutations in DNA – UV radiation changes the structure of DNA, can lead to
protein malfunction or cancerous cells/tumors
Reduced Biological activity:
◦ Damage and kill plant cells
◦ Affect ability of enzymes, could prevent photosynthesis
◦ Increase mortality rate in marine algae and phytoplankton