Environmental Consequences of Human Activity

4th Highlight / Objective 2

Students should know that human activity, both negative and positive, may result in

environmental consequences (such as loss of habitat or overdevelopment in sensitive areas) but that there may be degrees of

consequences. For example, environmental change does not necessarily lead to

extinction of species- there may be a more gradual process that allows for recovery, as

with the American bald eagle.

TEK 8.11 The student knows that traits of species can change through generations and that the instructions for traits are contained in the genetic material of the

organisms.

Student Expectation (A): The student is expected to identify that

change in environmental conditions can affect the survival

of individuals and of species.

Environment

The combination of external physical conditions that affect and influence the

growth development and survival of organisms.

When environmental conditions change, pressure is put on an organism for survival. The trait which enables an organism to adapt to a particular environmental change

is inherited.

Change in climate

• Which set of offspring will inherit coloring best suited for the new environment?

? ?

Organisms can ADAPT to their environment if the traits they inherit allow for greater reproductive success

Environmental change

Natural Causes:

Tectonic Plate Movement

Weathering / Erosion

Volcanic Eruption

Rock Cycle

Water Cycle

Weather / climate change

Forest Fire

Meteor Crash

Human Causes:

Pollution

Fossil fuel burning/ CO2 levels rising

CFC emission destroying ozone layer

Pesticides

Acid Rain

Loss of Natural Resources

Oil and coal

Destruction of Natural Habitat

Deforestation

The environment is constantly changing, so populations of organisms

are also constantly changing.

What happens to an organism if

it is not successful in adaptation?

Sometimes environments change so drastically that a species cannot adapt in time and it

becomes extinct.

Many scientists believe 65 million years ago a giant meteor crashed into earth changing life so drastically that many dinosaurs and plants became extinct.

Extinction is the death of an entire species.

Examples of extinct animals are:

Dinosaurs

Dodo

Extinct 1681

Extinct: CretaceousPeriod

Very often however, the consequences from environmental change is not so drastic as extinction.

Populations may be reduced in number, but rather than die out.

They may become endangered or threatened.

Grey wolf

panda

MexicanSpotted owl

Loggerheadturtle

Humpback whale

Endangered species are in danger of becoming extinct.

Threatened species are likely to become endangered in the foreseeable future.

Until recent sightings in Arkansasduring 2004-2005,the ivory-billed woodpecker was believed to be extinct. It is now classified as endangered.

Human activity does not always produce a negative environmental impact.

Pressure from special interest groups have helped with the creation of laws

and practices that are designed to help reverse the negative impact on the environment due to human activity.

The American bald eagle * 1500s- Half a million American bald eagles in U.S.* Mid 1940s- Widespread use of DDT as insecticide* Mid 1950s- Steep decline in bird-of-prey populations* 1960s- “Silent Spring” published

Severe reduction in hatching of American bald eagle due to soft shells caused byDDT contamination in the diet.

*1970s- Only 791 eagle breeding pairs found*1972- U.S. banned the use of DDT as pesticide*1973- Endangered Species Act passed by

Congress*1998- 6,000 breeding pairs found in North

America*2000- Eagle taken off endangered species list

Sample Test Question

AmericanBaldEaglePopulation(Breeding pairs)

Years

Changes in eagle population from 1500-2000

1950 1960 1970 1980 1990 2000

500

1000

1500

2000

5500

6000

6500

Based on the information plotted on the previous graph, which kind of human activity most likely impacted the environment between the 1950s-1970s?

A. Bird sanctuaries were built by environmentalists

B. DDT was widely used as a pesticide.

C. 6,000 breeding pairs were found in the U.S.

D. Endangered Species Act was passed by Congress

During the span of 1950-1970, the population

of the American Bald Eagle dropped

significantly, so the only answer choice that

would logically cause a decline in

population is B- the use of DDT.

Explanation:

Sample Test Question

AmericanBaldEaglePopulation(Breeding pairs)

Years

Changes in eagle population from 1500-2000

1950 1960 1970 1980 1990 2000

500

1000

1500

2000

5500

6000

6500

Using the same graph, which type of human activity most likely accounted for the change in American Bald Eagle Population between 1970-1998?

A. The American Eagle was taken off the endangered species list in 2000

B. Widespread use of DDT as a pesticide

C. The U.S. banned the use of DDT as a pesticide in1972.

D. Only 791 eagle breeding pairs found in 1970.

Explanation

Between 1970-1998, the American Eagle populationIncreased dramatically, and “C” indicates the banOf DDT which should help eagle populations rise.

The answer would not be “A” since the action wouldHave to come before the eagle would be taken off the Endangered list.

The answer would not be “B” since using DDT wouldDecrease eagle numbers.

The answer would not be “D” because collecting dataIs not a human activity causing impact.

Panda bears have teeth for crushing plants and

opposable thumbs for grasping which are

adaptations that enable them to graze on

bamboo forests. The populations have been

declining due to human activity causing habitat

loss, and are now endangered. How could the

World Wildlife Fund best spend money in

efforts to save the panda from extinction?

Sample test question

A. Provide shelter for pandas from cold winters.

B. Provide medical specialists who can encourage breeding of pandas

C. To buy and spread insecticide to increase health and vigor of bamboo forests.

D. To support legislation which encourages the deforestation of bamboo forests.

l

Answer “A” is not a good choice since the plight of pandas has nothing to do with climate.

Answer “B” is not a good choice since the problemis related to their loss of habitat, not inability to breed.

Answer “D” is not a good choice, since it encourageshabitat destruction.

Answer “C” is a good choice because this action is designed to enrich the panda habitat.

Image credits

• http://www.nasa.gov (meteor crash)

• http://en.wikipedia.org/wiki/Dodo (Dodo)

• http://en.wikipedia.org/wiki/Ivory_billed_woodpecker (woodpecker pic)