Option G3 Impact of Humans on Ecosystems

1. Option G3Impact of Humans on Ecosystems

2. Alien Species • An alien species is one which arrives in a non-native habitat. • Introduction of an alien species may be intentional or accidental • Often they are not well adapted to the new habitat so it will not survive • Some can adapt well and become very invasive causing ecological and economic damage. Examples: Zebra Mussel – accidental release Japanese Knotweed – deliberate introduction Cane Toad – biological control

3. Zebra mussels – an invasive species • Dresseniapolymorphais native to the Black and Caspian Seas • Accidental release into the Great Lakes through the ballast water of ships in the mid 1980’s • First found in Lake St. Clair and quickly spread to L. Ontario • Has spread throughout all the great lakes and most waterways in eastern North America

4. Few natural predators. Takes over niche of native mussels Will grow on any hard surface – pipes, boats, rocks, other organisms Clogs water intake pipes Filters water and removes water contaminants. These contaminants passed through the food chain Biomagnification! Cleared up Lake Erie water Impacts of the Zebra Mussel

5. Round Goby – an invasive species • - Round Goby • - Survives well in degraded environmental conditions • Competitive advantage compared to native species. • Heavy feeding on invasive mussels • (zebra and quagga) results in greater biomagnification • - No predators due to defensive mechanism

6. Japanese Knotweed -deliberately introduced • Fallopia japonica is an aggressive semi-woody perennial plant that is native to eastern Asia. • Was introduced in the 1800′s it was introduced to North America as an ornamental species and also planted for erosion control • Has a vigorous root system that can spread up to 10m from the parent stem. Very difficult to control. • Reduces plant biodiversity by competing with other native vegetation. • Roots are known to break through asphalt and concrete.

13. Define biomagnification – At each trophic level, toxic substances (Hg, pesticides, TCDD, etc.) become more concentrated

14. The Ozone Layer • The stratosphere is located 15-40 km above the Earth’s surface • The ozone layer is the “Earth’s sunscreen” and absorbs 93% of UV radiation from the sun • Ozone is continually being broken down and reformed by UV radiation O2 + O  O3 • The presence of CFC’s causes thinning of the ozone layer

15. http://www.youtube.com/watch?v=qUfVMogIdr8

16. Montreal Protocol • An international agreement to reduce the use of substances that deplete ozone by 2000such as those used in: • refrigerator coolants • propellants in aerosols • manufacturing of foam packaging • The treaty was originally signed in 1987 with amendments in 1990 and 1992 • Size of the ozone hole peaked in 2001 and has now started to shrink • Estimated by 2070 it will have disappeared

18. Effects of Ultraviolet Radiation • Non-lethal skin cancer (carcinoma) • Lethal skin cancer (malignant melanoma) • DNA mutations (Thymine dimers) • Sunburn – leads to skin cancer

19. Cataracts – clouding of the lens of the eye leading to loss of vision • Suppression of the immune system • Reduction in growth of phytoplankton in Ocean’s • UV damage kills plant cells and reduces photosynthesis