Invasive species and Overexplotation

Exotic: Organisms that have been introduced by human activity into an ecosystem where they are not native.

Invasive species: Exotic that spreads naturally into natural or semi-natural habitat, they increase in abundance at the expense of native species.

Introduction of Invasive species?1.Accidental introduction.

2.Purposeful introduction and accidental spread.

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Harmful Impacts1. Out-compete native species.

2. Cause disease in native species.

3. Prey on native species to point of extinction.

4. Degrade habitats so that native are no longer to persist.

Invasive species of Pakistan• Eucalyptus plant was imported from

Australia.• Consume more water (disturbed• water table).• It harm plants growth near by. 3

Paper Mulberry in Islamabad • Native to eastern Asia.• Introduced for its scenic value, but is now

replacing the native flora at an alarming rate.• High consumption of water, which leaves less

water to sustain the native flora.

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Purple loosestrife• Introduced from Europe and dominated many

North America wet land.• So aggressive that it chokes out native

plants, destroying wildlife habitat

1968 1978

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Zebra mussels• First introduced in the Great Lakes by ballast

water.• Multi-billion dollar threat.• They out-compete native mussels.• Within two year of introduction ,

they reached densities of 700,000.

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Comb jelly

• 1982 Black Sea introduction is accidentally by ballast water.

• It caused a dramatic drop in fish populations by competing for the same food sources .

• Biological control was

tried with Beroe ovata,

another comb jelly,

with some degree of success

has been achieved.7

lamprey• Primitive jawless fish—has a sucker mouth• Parasite that attaches to large fish• Came into the Great Lakes from the Atlantic

Ocean• Only about 1 in 7 fish survive attack by

lamprey

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Fire Ants• In southern United State, diversity of insect

species decline 40% after the invasion of exotic fire ants

• abundance of northern bobwhite in Texas has decline over a 20 year period(effect at nestling stage)

• Nuisance to people.

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Brown Tree snake• Introduced onto number of Pacific islands • It devastate endemic bird population by

eating eggs, nestling and adult birds.• Invasive species has driven 8 of 11 forest

species extinct.

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OVER EXPLOTATION

Def: Overexploitation is the use, by the human, of a natural resources to an extant, that is not sustainable.• Also called as overharvesting.

Causes of Overexploitation1.Possibly rich countries over consume.

2.Increase in human population number.

3.Lack of incentive to conserve biodiversity.

4.Results from large ,poor ,rural population and

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extensive use of wildlife for both food and traditional medicines

5. Improve methods of harvesting leading to the empty habitat.

EXAMPLES:

Commercial exploitation of whale• Whales are slaughtered for spermaceti oil (oil

form sperm whale) meat, baleen(whale bone) leads to the decrease in the population of the whale.

• International whaling commission IWC regulates whale hunting.

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International trade in fur

Mamo Bird• A single ceremonial cloaks worn

by Hawaiian king were made from feathers of Mamo birds.

• A single cloak use the feathers of 70,000 birds of this now extinct species.

 Carolina parakeet • The only parrot species native to

the eastern United States, was hunted for crop protection and its feathers. 13

The Great Auk• The bird had few natural predators, it has no

fear of human which made them easier to hunt.• It was found in Canada, Greenland, Iceland,

Norway and great Britain.• Being flightless it was a

hunters dream.• The bird was used for

• food and feathers.

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Bluefin tuna• The northern bluefin tuna is currently seriously

overexploited. • Scientists say 7,500 tons annually is the

sustainable limit, yet the fishing industry continues to harvest 60,000 tons.

• Commercial fishing demonstrates that industryworking one species after another to the point of diminishing returns a processsome time terms fishing down the food chain.

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The Amphibian and Reptile Industry ,Food:

• Certain frog species are particularly persecuted along with a few lizards, turtles, crocodiles and alligators.

• The USA import 2.5 million kilogram frog legs from Japan and India.

• Brightly colored frogs, such as the Poison or dart frogs are also threatened by overexploitation for sale in the pet trade.

• Because of bright colored they are highly valued by hobbyists.

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• CORAL REEF

• The rich diversity of marine life inhabiting coral reefs attracts bioprospectors. Many coral reefs are overexploited.

 

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• Other species affected by overexploitation include:

• The international trade in fur: chinchilla, and numerous cat species.

• Insect collectors: butterflies

• Shell collectors: Marine molluscs

• Aquarium hobbyists: tropical fish

• Chinese medicine: bears, tigers

• Novelty pets: snakes, parrots and primates

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• RHINOCEROS become rare due to overexploitation the price of its horns rises making its more value able on black market .

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• CONTROL OF OVER EXPLOITATION:• 1. RIGHTS TO SPECIFIC HARVESTING

TERRITORY were rigidly controlled.• 2. Hunting and harvesting in certain areas

must be banned.• 3. Prohibition against harvesting female

juvenile and undersized animals• 4. Efficient methods of harvesting is not

allowed • 5. Certain season of years and time of the

days were close for the harvesting.

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