Notes: Human Influences on Environment and Pollution (pg. 16-18)

• I. LOSS OF BIODIVERSITY– Biodiversity- is the

variety of life in an area. This is a necessity because organisms depend upon one another (food chain).

• Threatened Species– Species population

begins to decline rapidly

– Example: African Elephants

• Endangered Species: Number in population become so low that extinction is possible

• Extinction– Disappearance of a

species when the last member dies

– Since early 1980 40 plant and animal species have become extinct

Causes of Extinction• Overfishing:

harvesting of fish or shellfish faster than the population can renew its numbers

• Example: Eastern oyster

• Overhunting: killing of organisms for food, fur, feathers or other body parts at a faster than the population can renew its numbers.

• Example: blue whale, tigers, snow leopards, elephants, rhinoceroses

Eastern Oyster• Keystone species along

NC estuaries• Serve 3 major roles: food

source, clean the water, provide habitat (build reefs)

• Overharvested, water pollution and habitat destruction led to 90% decline in population

• Result: increased pollution in estuaries and decline in other aquatic species.

African Elephants

• Population decline due to the poaching of elephants for their tusks which are made of ivory.

• Threatened Endangered Extinct

II. What Humans Have Done to Affect Biodiversity

• Habitat Loss- Organisms lost homes and shelter because of human interaction

Deforestation• Removal of all trees of a forest for either land

development or wood supply.• Not only results in habitat loss but also contributes to

global warming as CO2 levels increase

Piedmont Urbanization

• As the population grows in the piedmont region of NC, there is a demand for more land development (homes, schools, roads, shopping centers)

• This leads to habitat destruction

Coastal Development

• Increased development to meet population increases

• Beach erosion leads to changes in natural habitats as well as alters beach ecosystems.

• Habitat Fragmentation- Separation of wilderness from other wilderness area.– Construction of roads or buildings in nature

• Habitat Degradation- Damage to habitat by POLLUTION. Example: acid rain or the depletion of the ozone layer.

Keystone Species:

• A species that plays a critical role in the community of an ecosystem

• Example: Eastern oyster

Introduction of invasive species

• An introduced species that is not native to that ecosystem

• Can wreak havoc due to having no natural predators or competition

• Example: – Kudzu– Rodents/insects

traveling on cargo ships from other countries

Kudzu• Imported from Asia in

the 1800’s to help with soil erosion.

• Has outcompeted native plants and resulted in population decline of some small ground plants and can kill trees.

• Grows rapidly and few animals feed on it

Resource Destruction:

• Renewable resources- can regenerate if they are alive or can be replenished by biochemical cycles as quickly as they are used.

• Examples: soil, water, air, forests

• Nonrenewable resources- cannot be replenished by natural processes as quickly as they are used.

• Examples: fossil fuels, minerals, metals

• Use of new technology requires certain minerals that can depleted rapidly as use is increased

• Global Warming– The overall warming of

our earth (a.k.a. the greenhouse effect) caused by increased levels of carbon dioxide that is released naturally by respiration and by the burning of fossil fuels.

– See carbon cycle notes to review more causes of carbon dioxide release

Global Warming

• Increase in temperatures has lead to ice caps and glaciers melting:– increases sea level

which can flood coastal towns

– Results in habitat loss for polar bears

Global Warming• Extreme weather

changes have been contributed to increases in global temperature

• Example: Super storm Sandy

• Destruction of the Ozone Layer– Caused by the use of chlorofluorocarbons

(CFCs) (primarily found in aerosols and coolant systems)

– Ozone layer is a natural sunscreen for our earth, it is diminishing and allowing more ultraviolet (UV) rays to pass through which has been correlated to increased cases of skin cancer.

Pesticide use- Rachel Carson wrote Silent Spring and made the public aware of the DDT pesticide problem

• Pesticides are used to kill pests but can sometimes kill organisms that aren’t targeted.– Runoff can carry them into aquatic

ecosystems.

Bioaccumulation:

• Pesticides (or pollutants) are passed through the food chain

Biomagnification:

• The highest amount of pesticides (or pollutants) are found at higher trophic levels due to the consumption of organisms with trace amounts of pesticides (or pollutants) at lower trophic levels.

Biomagnification:

• Major animal affected:

Bald eagles and peregrine falcons decreased due to soft shells from exposure to DDT. This resulted in fewer chicks surviving and hatching and a population decrease.

Pollution:

• Pollutants that are released in one area often have an impact on a much larger area. The plume is the area that a substance touches (smoke stack in air or a pesticide in ground water)

Pollution:

• Release of harmful substances or energy into air, water or soil.– Burning fossil fuels releases carbon dioxide– Deforestation reduces numbers of plants that

take in carbon dioxide– Ground water or runoff carrying pesticides

from crops into water supply

Eutrophication:

• Excess nutrients are released into a body of water.

• Example: Waste lagoons on NC hog farms

Waste Lagoons• Phosphorous and nitrogen

compounds such as nitrates can seep into the soil

• Carried to aquatic ecosystems by groundwater or runoff

• Excess nutrients cause a population explosion of algae creating an algal bloom

• Algae thrives on nutrients and exceeds carrying capacity so they begin to die

• Decomposers become active on the algae which uses more oxygen

• Less oxygen available to other organisms which results in death of other organisms

Acid Rain• Rain that has a pH

lower than 5.6– Caused when sulfur

and nitrogen released from the burning of fossil fuels combine with water in the atmosphere

– Harmful to plants and the animals that eat the plants