Option G G3: Impacts of humans on ecosystems

1. Option G G3: Impacts of humans on ecosystems

2. Calculate the Simpson diversity index for two local communities. See Handout

3. Analyze the biodiversity of the two local communities using the Simpson Index • See Handout

4. Discuss reasons for the conservation of biodiversity using rainforests as an example • Your views…they must include ethical, ecological, economic and aesthetic arguments

5. List 3 examples of the introduction of alien species that have had significant impact on ecosystems • 1. Biological control: releasing ladybugs to kill aphids on roses in the garden. • 2. Accidental release: zebra mussels being moved around the world in ballast water for boats, the zebra mussels compete with native mussels. • 3. Deliberate release: cane toads in Australia (to kill cane grubs, which didn't work. Plus, the cane toads outcompeted a lot of native wildlife)

6. Discuss the impact of alien species on ecosystems (3 impacts with named examples of each). • Interspecific competition (alien zebra mussels vs. native mussels, alien thistle vs. Colorado wildflowers); • Predation(alien dogs and cats killing birds like the dodo); • Species extiction(dodo); • Biological control of pest species (ladybugs and aphids; failed attempt with cane toad and cane grubs)

7. Outline one example of control of an invasive species • Kill them (ie thistles in Colorado meadows), • Move them (ie take goats out of nature reserves in New Zealand), • Ideally prevent their entry (hence the rules about fruit at the airport)

8. Define: Biological Magnification • Biomagnification is the process in which chemical substance become more concentrated at each trophic level (don't confuse with bioaccumulation, which is within an organism during its lifetime)

9. Explain the causes and consequences of biomagnification using a named example DDT is sprayed on crops to control insects. It washes off into rivers and lakes and gets on aquatic plants and phytoplankton (producers) at low comcentrations. Little fish eat these producers and build up higher and higher levels of DDT in their lifetimes (bioaccumulation). In the next trophic level, a medium-sized fish will consume many small fish, concentrating all of the DDT from all of the little fish in their bodies. When birds eat large fish and medium fish then they get all of the DDT from those fish. The concentration has increased at each trophic level--biomagnification. • DDT is sprayed on crops to control insects. It washes off into rivers and lakes and gets on aquatic plants and phytoplankton (producers) at low concentrations. Little fish eat these producers and build up higher and higher levels of DDT in their lifetimes (bioaccumulation). In the next trophic level, a medium-sized fish will consume many small fish, concentrating all of the DDT from all of the little fish in their bodies. When birds eat large fish and medium fish then they get all of the DDT from those fish. The concentration has increased at each trophic level--biomagnification.

10. Outline the effects of ultraviolet (UV) radiation on living tissues and biological productivity. • UV damages DNA causing mutations. • Biological productivity is decreased (reduces photosynthetic rates in plants and algae). • It also damages tissues, increases rates of skin cancer, causes cataracts.

11. What absorbs UV radiation and reduces the amount people on Earth are exposed to? • Stratospheric Ozone

12. Outline the effects of CFCs (chlorofluorocarbons) on the ozone layer • CFCs cause ozone (O3) to break down to oxygen gas (O2).