What is Human Impact?

Ecology is the study of the interactions of organisms with its environment. Biodiversity is the variety of life in an area; # of species in an area

Population Growth Populations grow when birth rate exceeds rate of mortality. Carrying capacity of humans is still unknown

Humans are part of the Earth's ecosystem. Human activities can either deliberately or inadvertently alter the balance of an ecosystem.

How do human activities affect the environment?

Global warming  is a slight increase in the earth’s average temperature.  Use of machinery by humans seems to be increasing CO 2 levels in the air.  CO 2 prevents heat from escaping, causes slight world wide temperature increases

 Greenhouse effect: When heat from the sun bounces of the earth’s surface some of it is trapped in the atmosphere by greenhouse gases. -Without it the earth’s surface would be too cold to support life.  Too many greenhouse gases (mainly carbon dioxide) have been released into the atmosphere trapping in too much heat.

 The major cause of global warming is the burning of fossil fuels. When fossil fuels are burned they release carbon dioxide.  growth of the human population (all organisms release carbon dioxide)  Deforestation (Plants remove carbon dioxide from the atmosphere by photosynthesis).

 Changes in global climate patterns.  The organisms that live in some biomes may not be able to survive.  Changes in climate patterns could also reduce the world’s food supply.  Melting of the polar ice caps would increase sea level, leading to the flooding of coastal habitats.

Deforestation  Caused by demand for wood products, need for space, farmland, housing, roads  Deforestation causes habitat loss --- Animals and plants are forced into confined areas

Habitat Loss

Ozone depletion  Caused by aerosol chemicals called chlorofluorocarbons (CFCs)  CFC’s -Escape into atmosphere, reacts breaking down the ozone (O 3, a protective atmospheric layer) -UV rays penetrate the atmosphere and cause harm to many organisms

“HOLE” in the ozone (O3)

Fishing activities  Demand for fish and shellfish  Commercial Fishing be harmful to environment in many ways

Invasive species (EXOTIC SPECIES)  introduced by people accidentally or intentionally  Can cause problems if no natural enemies are present -Cane toad was introduced to Australia to control cane beetles, pest insects that destroy sugar cane crops

Exotic pet trade  Capture and sell wild animals from exotic locations  Wealthy buyers and collectors desire obscure animals  Animals removed from their habitat causes an imbalance in the ecosystem

Biodiversity = Many different types of organisms Organisms depend upon one another Interfering with one Organism can have a Ripple effect to many w/in the habitat

Natural resources: Non-renewable includes fossil fuels (petroleum, coal, oil)  Renewable includes animals, plants, water, wind, etc. even renewable resources can run out

Natural resources Renewable energy sources include wind power, geothermal energy, ocean currents

 Pollution is any undesirable factor added to the air, water, or soil.  Smog is one type of air pollution.  Acid rain is caused by fossil fuel emissions

Acid Rain -Any precipitation that has a lower pH (more acidic) than normal. -Formed when sulfur and nitrogen compound released into the atmosphere combine with water vapor and create sulfuric and nitric acids. -The sulfur and nitrogen compounds are released when fossil fuels are burned.

If acid rain can destroy rock, imagine what it can do to a fragile fish egg.

 Damages the leaves of trees and can eventually lead to the death of the tree.  Lowers the pH of lakes and streams, which can kill the organisms in the lake or stream including producer organisms like algae.  It can also kill the eggs of some fish, and sterilize some fish.  Some lakes have been so acidic that nothing lives in them.

 Conserve energy (turn off lights, computer, and TV’s when not in use, turn down heat when no one is home and at night, hang clothes to dry, decrease time in the shower, etc.)  Use alternate energy sources (nuclear, solar, wind, or hydroelectric power)  Carpool, walk, or ride a bike when possible.  Burn cleaner coal  Place scrubbers (filters) on smoke stacks that remove the sulfur and nitrogen compounds. 

Water Pollution  water can be polluted with human sewage, pesticides, herbicides, fertilizers, and toxic wastes (poisons) from factories.  As a result the abiotic conditions of the water change. For example, changes in temperature, pH, and oxygen content.

 produced when pollutants in the water cycle cause rain pH to drop  can lower the pH of a lake or stream  can harm trees

 Agricultural DDT Fertilizers Animal wastes (nitrogen)  Homes Strong cleaning agents  Industry Toxic gases and wastes Acid rain

 Biomagnification causes accumulation of toxins in the food chain. -Pollutants can move up the food chain.  predators eat contaminated prey  pollution accumulates at each stage of the food chain  Top consumers, including humans, are most affected.

 The application of science to increasing agricultural productivity, including the breeding of high-yield varieties of grains, the effective use of pesticides, and improved fertilization, irrigation, mechanization, and soil conservation techniques.