Option G3 Impact of Humans on Ecosystems
description
Transcript of Option G3 Impact of Humans on Ecosystems
Option G3Impact of Humans on
Ecosystems
Alien SpeciesAn 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 releaseJapanese Knotweed – deliberateintroductionCane Toad – biological control
Zebra mussels – an invasive speciesDressenia polymorpha is native to the Black and
Caspian SeasAccidental release into the Great Lakes through the
ballast water of ships in the mid 1980’sFirst found in Lake St. Clair and quickly spread to L.
OntarioHas spread throughout all the great lakes and most
waterways in eastern North America
Impacts of the Zebra MusselFew natural predators. Takes over niche of native
musselsWill grow on any hard surface –
pipes, boats, rocks, other organisms
Clogs water intake pipesFilters water and removes water
contaminants. These contaminants passed
through the food chain Biomagnification!
Cleared up Lake Erie water
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
Japanese Knotweed -deliberately introducedFallopia 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.
Define biomagnification – At each trophic level, toxic substances (Hg, pesticides, TCDD, etc.) become more concentrated
The Ozone LayerThe stratosphere is located 15-40 km above the
Earth’s surfaceThe ozone layer is the “Earth’s sunscreen” and
absorbs 93% of UV radiation from the sunOzone is continually being broken down and
reformed by UV radiationO2 + O O3
The presence of CFC’s causes thinning of the ozone layer
http://www.youtube.com/watch?v=qUfVMogIdr8
Montreal ProtocolAn international agreement to reduce the
use of substances that deplete ozone by 2000such as those used in:refrigerator coolantspropellants in aerosolsmanufacturing 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
Effects of Ultraviolet RadiationNon-lethal skin cancer (carcinoma)Lethal skin cancer (malignant melanoma)
DNA mutations (Thymine dimers)Sunburn – leads to skin cancer
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