1. Option G Ecology and Conservation
G1- Community Ecology
G2- Ecosystems and Biomes
G3- Impacts of Humans on Ecosystems
Test
G4- Conservation and Biodiversity
G5- Population Ecology

2. G3- Impacts of Humans on Ecosystems

3. Simpson Diversity D= N(N-1) ∑n(n-1)
Calculate the Simpson Diversity index for two local communities.
D= N(N-1)
∑n(n-1)
D= Diversity index
N= total number of organisms of all species found
n= number of individuals of a particular species
∑ = sum
Use a random sampling technique to search for organisms in the ecosystem
Identify each of the organisms found.
Count the total number of individuals of each species.
Calculate D
Compare to another site or previous data

4. Simpson Diversity
2. Analyze the biodiversity of the two local communities using the Simpson index.
The Simpson diversity index is a measure of species richness of an ecosystem.
A high value of D suggests a stable and ancient site with greater diversity. No stress.
A low D value could suggest pollution, recent colonization or agricultural management.
The index is normally used in studies of vegetation but can also be applied to comparisons of animal (or even all species) diversity.
Changes in the index indicate environmental change.

5. Simpson Diversity Example

6. Rainforest Biodiversity
3. Discuss reasons for the conservation of biodiversity using rainforests as an example.
Economic-
Pros
New medicines- pharmaceuticals can be derived from tropical rainforest species
Food and materials for local populations
New Crops of plants or farm animals existing varieties could be improved using genes from wild species
Ecotourism- huge industry
Habitat and species for education and research
Cons
Conservation measures slow economic development
Clearing provides land for agriculture
Clearing opens up communication routes

7. Rainforest Biodiversity
Ecological-
Pros
50% of known species are found in the tropical rainforests.
Contain species yet to be described
Extinction of species
Species are interdependent- if 1 species goes extinct it will affect the community
Native species are adapted to local conditions, alien species are unlikely to be as well adapted
Destroying rainforests will cause climate change
Rainforests are a sink for CO2
Rainforest prevent soil erosion
Disruption of water/nutrient cycles
Cons
Reservoirs for pest species that transmit disease

8. Rainforest Biodiversity
Ethical-
Every species has a right to life
Cultural importance of ecosystems- Humans should be responsible stewards of the Earth’s organisms
Not fair to future generations to destroy the Earth’s biodiversity

9. Rainforest Biodiversity
Aesthetic
Beautiful
Inspirational

10. Alien Species
4. List three examples of the introduction of alien species that have had significant impacts on ecosystems.
5. Discuss the impacts of alien species on ecosystems.
6. Outline one example of biological control of invasive species.

11. Alien Species
Alien species: a type of organism that humans have introduced to an area where it does not naturally occur.
Some alien species have been introduced intentionally and some accidentally.
Alien species are sometimes very invasive and cause considerable ecological damage.
When alien species are introduced into a new area they tend to thrive because they have no natural predators.
They out compete the native species and sometimes cause the native species to go extinct.
Humans have tried to use biological controls to rectify the situations.
However, biological controls require the introduction of another alien species.

12. Alien Species Example 1
Salvinia molesta, Floating Ferns, has been transported around the world as an aquarium or pond plant.
It has damaged many lakes in the tropics and subtropics.
It grows rapidly, doubling the number of leaves in about 2 weeks.
It eliminates native plant species by interspecific competition.
Biological control: Another alien species, Cyrtobagus salviniae, Salvinia Weevil, has been introduced to control the floating ferns by feeding on them.

13. Alien Species Example 2
Three species of rats were introduced to the mainland of New Zealand during the 19th century.
They caused many species of birds to disappear from the mainland- Species Extinction.
The rats fed on the eggs and young birds causing the populations of birds to plummet.
Some species survived by moving to islands that did not contain the rats.
This also happened in the Galapagos Islands with black rats causing the extinction or near extinction of many bird species and the giant land tortoises.

14. Alien Species Example 3
Kudzu was introduced from Japan into the southeast US in 1876 as an ornamental plant
It grows over 20 meters a season
It grows horizontally and vertically
It crushes and covers ground plants and grows along tree branches, the excess weight breaks the branches

15. Biomagnification 7. Define Biomagnification.
Biomagnification- a process in which chemical substances become more concentrated at each trophic level.

16. Biomagnification
8. Explain the cause and consequences of biomagnification, using a named example.
Some pollutants are absorbed into living organisms and accumulate because they are not efficiently excreted.
When a predator consumes prey containing the pollutant and absorbs it, the level in the body of the predator rises and can reach levels much higher than those in the bodies of its prey.
This increase is called biomagnification and it can happen at each stage in the food chain.

17. Biomagnification Example: DDT
Dichloro-diphenyl-trichlorethane is an organochloride (DDT) pesticide that was invented during World War II and used to wipe out Malaria in North America and prevent other insect born diseases.
DDT can be applied to agricultural crops to eliminate pests, wetland areas to kill aquatic insect larva, or even the walls of homes to prevent malaria-carrying mosquitoes from entering.

18. Biomagnification: DDT
After its application, DDT is absorbed into the bodies of the insects where it then proceeds to attack the cell membranes.
The cells that are most greatly affected by DDT are the neurons in the insects.
DDT is absorbed across the plasma membrane of the cells causing leaks in the membrane which allow potassium and sodium ions to escape.

19. Biomagnification
The reason that DDT affects the eagles and many other facets of the environment so strongly is because of the principle of biomagnification.
DDT is a very persistent chemical that does not readily break down in the environment.
It is also not soluble in water so once it is sprayed, it often remains for decades.
DDT is readily fat soluble, so after the chemical is consumed by an herbivore, it is stored in the organism’s fat cells.
When that first organism is later consumed, the DDT in its fat will be consumed by the predator and incorporated into its anatomy as well.
The DDT never leaves the systems of the animals it is in until it is consumed, so the levels of the chemical are amplified as you move up the food chain.
In top predators the quantities become so high that numerous undesirable effects are observed.

20. Biomagnification
The most well known example of this is the calcium depletion in bald eagle eggs.
This depletion makes the eggs very soft and unproductive of the embryo, which restricts the proper and full development of the bald eagle young.
This caused a great drop in the overall bald eagle population which in turn lead to a nationwide ban of DDT use in June of 1972.
The bald eagle has made a come back.

21. Effects of UV Radiation
9. Outline the effects of ultraviolet (UV) radiation on living tissues and biological productivity.
UV radiation can kill phytoplankton, the sea-going organisms that account for a significant portion of net photosynthesis that occurs in the biosphere.
The radiation can also retard growth of terrestrial plants by slowing their rate of photosynthesis, usually a result of radiation damage and subsequent mutations caused in plant leaves.
High levels of UV light can also kill symbiotic nitrogen-fixing bacteria.

22. Effects of UV Radiation
What does UV do to living tissue?
Causes mutations in DNA by forming free radicals
Causes dimer formations which bend or kink the DNA
DNA repair system does not function properly
Causes benign and malignant tumors (cancer, especially skin cancer)
UV converts ergosterol to Vitamin D.
Causes sun tan, sunburn, and cataracts
UV radiation can also weaken and potentially destroy the cells of the immune system.

23. CFCs
10. Outline the chemical effect of Chlorofluorocarbons (CFCs) on the ozone layer.
Measurements of ozone concentrations in the stratosphere have shown that there has been a depletion throughout the world.
Since the 1980’s an ozone ‘hole’ has appeared over the Antarctic every year between September and October, which persists for several months.

24. Cl + O3  ClO + O2  ClO + O  Cl + O2
CFCs
Chlorine reacts with ozone and breaks it irreversibly into oxygen.
One chlorine atom can break thousands of ozone molecules.
This leads to depletion of the ozone layer and the passage of UV light through the ozone hole.
Cl + O3  ClO + O2  ClO + O  Cl + O2
In this cycle each Cl atom may destroy more than 100,000 O3 molecules before being carried back into the lower atmosphere.

25. CFCs
CFC’s (chlorofluorocarbons) are the main cause of ozone depletion.
They are chemical compounds manufactured by humans and released into the atmosphere.
UV light causes CFC’s to dissociate and release Cl. The Cl then reacts with O3 to break down ozone.
CFC’s were used widely in the 1970’s and 1980’s in refrigerant, propellant (spray paint cans, hairspray), and in gas-blown plastics used for fast- food packaging.

26. Reducing CFC’s To reduce the release of ozone depleting substances:
1. Filters can be fitted on factory chimneys to absorb and react with gases before they escape into the atmosphere, desulphurization (removal of sulfur) of gases before they are emitted into the atmosphere
2. Alternative sources of energy such as wind, hydroelectric, waves, solar, tidal, geothermal and others.
3. Methane and alcohol as fuels since they do not release sulfur and other harmful gases into the atmosphere.
4. A ban on CFC-based propellants has been enacted, and most corporations now recycle the refrigerants used rather than produce entirely new ones.

27. Reducing CFC’s
In 1987, an international treaty called the Montreal Protocol was signed. The treaty sets targets for the replacement of CFC’s with other chemicals that do not damage the ozone layer countries have signed it, but not China, India, Korea, or Mexico with combine for 35% of the world’s population.
Although the levels of CFC’s are continuing to rise, they should start to fall by 2010 although slowly. Computer models predict that by 2050, ozone holes over the poles will no longer form.

28. Ozone 11. State that ozone in the stratosphere absorbs UV radiation.
The ozone absorbs short wave radiation, especially UV.
The amount of UV radiation reacting the Earth’s surface is greatly reduced by the ozone layer.
Ozone (O3) is a molecular form of Oxygen, when UV light or lighting strikes an oxygen molecule, it splits the molecules into free oxygen atoms.
The atoms of oxygen are highly reactive and can combine again to form ozone. In doing this, they release heat. This results in the conversion of UV light energy into heat energy.
There is a limit to UV absorption in the stratosphere.