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.

Change in climate 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.

? ? 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

What happens to an organism if it is not successful in adaptation? 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 Extinct: Cretaceous Period Dodo Extinct 1681

Populations may be reduced in number, but rather than die out. Very often however, the consequences from environmental change is not so drastic as extinction. panda Loggerhead turtle Grey wolf Mexican Spotted owl Humpback whale Populations may be reduced in number, but rather than die out. They may become endangered or threatened.

Endangered species are in danger of becoming extinct. Threatened species are likely to become endangered in the foreseeable future. Until recent sightings in Arkansas during 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- 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

Changes in eagle population from Sample Test Question Changes in eagle population from 1500-2000 6500 6000 5500 American Bald Eagle Population (Breeding pairs) 2000 1500 1000 500 1950 1960 1970 1980 1990 2000 Years

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 Explanation: 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.

Changes in eagle population from Sample Test Question Changes in eagle population from 1500-2000 6500 6000 5500 American Bald Eagle Population (Breeding pairs) 2000 1500 1000 500 1950 1960 1970 1980 1990 2000 Years

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 The U.S. banned the use of DDT as a pesticide in 1972. D. Only 791 eagle breeding pairs found in 1970.

Between 1970-1998, the American Eagle population Explanation Between 1970-1998, the American Eagle population Increased dramatically, and “C” indicates the ban Of DDT which should help eagle populations rise. The answer would not be “A” since the action would Have to come before the eagle would be taken off the Endangered list. The answer would not be “B” since using DDT would Decrease eagle numbers. The answer would not be “D” because collecting data Is not a human activity causing impact.

Sample test question 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?

A. Provide shelter for pandas from cold winters. B. Provide medical specialists who can encourage breeding of pandas To buy and spread insecticide to increase health and vigor of bamboo forests. To support legislation which encourages the deforestation of bamboo forests.

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 problem is related to their loss of habitat, not inability to breed. Answer “D” is not a good choice, since it encourages habitat destruction. Answer “C” is a good choice because this action is designed to enrich the panda habitat. l

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)