Loss of Biodiversity Section 1.1 & 1.2 PP 8-13

Extinction can be defined as the permanent disappearance of an organism. In other words, all the members of a species has died .This means a loss of biodiversity.

Extinction (Examples) The extinction of the Great Auk and the Newfoundland Wolf from our province has resulted in a lost of biodiversity.

When they are gone they are gone forever..... According to the David Suzuki Foundation, we are losing at least one per cent of existing species per decade, or at least two species an hour.  2,500 times greater than disappearance due to evolution or other natural processes .

When they are gone they are gone forever..... Between 1600 and 1900 it is estimated that one species went extinct every four years. In modern times, the rate is soaring. The graph below shows how the rate of extinction has increased over the past 30 years.

Graph Showing Rate of Extinction

Causes of Extinction 1. Natural Environmental Change 2. Competition 3. Loss of Habitat 4. Pollution of Air and Water 5. Climate Change

1. Natural Environmental Change The most promising theories involved asteroids crashing into Earth. There is evidence that an asteroid hit Earth about 65 million years ago. The crater, just off the Yucatan Peninsula of Mexico, is 9.6 km and 300 km wide

2. Competition If a new species enters an area, species that eat the same food must compete with it. The Banff long nose dace, a small minnow, was unable to compete with the guppies, and swordtails that were accidentally released below the hot springs in Banff National Park.

3. Loss of Habitat Logging, oil exploration, expansion of agriculture, road construction and expanding cities are destroying habitats. Frog species are exceptionally vulnerable to such expansion of human territory.

4. Pollution of Air and Water Pollution of the air by burning of fossil fuels such as coal, oil and gas by vehicles and industry can produce acid rain. Acid rain falls in lakes and ponds increasing the acidic levels.

4. Pollution of Air and Water  Also, run off  of fertilizers , pesticides and industrial waste into lakes and ponds can lead to extinction of aquatic dwelling organisms

5. Climate Change Human activities that are causing a change in climate have also been linked to the disappearance of organisms. There is evidence of a global warming trend. One hypothesis links increasing global temperatures with the increased use of fossil fuels by automobiles.

5. Climate Change Climate changes can cause important changes in local ecosystems. For example, if the climate becomes drier, frogs will suffer. No frog can stay in the sun too long or completely separate itself from fresh water.

Effects of Extinction Because every organism in an ecosystem is connected to all the other organisms, the reduction in biodiversity caused by the extinction of a single species can cause a “domino effect”. The removal of one part from an ecosystem can cause the collapse of an entire food chain.

Effects of Extinction For example, over hunting of sea otters along the west coast of North America removed the main predator of the sea urchin and the number of sea urchins increased.

Effects of Extinction Sea urchins eat kelp and as the number of sea urchins grew, the amount of kelp declined and so did the fish that relied on the kelp for food and habitat. Reintroducing the otter resulted in the fish numbers increasing

Classification System for At-Risk Species Species whose numbers are declining below a certain level are considered to be at risk. In Canada, more than 250 species of plants and animals are at various degrees of risk.

Classification System for At-Risk Species Five categories: 1. Extinct 2. Endangered 3. Extirpated 4. Threatened 5. Vulnerable

Classification System for At-Risk Species 1. Extinct…a species that is not found anywhere. Newfoundland Wolf

Classification System for At-Risk Species 2. Endangered a species that is close to extinction in all parts of Canada or in a significantly large location. Harlequin Duck

Classification System for At-Risk Species 3.Extirpated…. any species that no longer exists in one part of Canada but can be found in others Grizzly Bear

Classification System for At-Risk Species 4.Threatened any species that is likely to become endangered if factors that make it vulnerable are not reversed. Pine Marten

Classification System for At-Risk Species 5.Vulnerable....any species that is at risk because of low declining numbers at the fringe of it's range or in some restricted area.