Lecture 2Impact of Human Activities on Ecosystem

Lisa Antoniacci Ph.D.Marywood University

18.5 Human Effects on the Biosphere

• The increasing size of the human population and its increasing industrialization have far-reaching effects on the biosphere

• Effects range from extinction of individual species to global climate change

Increasing Species Extinctions

• Humans are increasing the rate of species extinctions by degrading, destroying, and fragmenting natural habitats, by overharvesting species, and by introducing exotic species

Increasing Species Extinctions

• Endangered species– Faces extinction in all or part of its range

• Threatened species– Likely to become endangered in the near future

• Endemic species– Evolved in one place and is found nowhere else

The Global Impact of Human Activities

• Human activities threaten entire ecosystems– Desertification– Deforestation– Air pollution and acid rain– Water pollution– Trash in aquatic ecosystems– Air pollution and the ozone hole– Greenhouse gases and global warming

Desertification

• Poor agricultural practices turn grasslands or woodlands into deserts– US Great Plains (the Great Dustbowl)– Sahara Desert

• Desertification– Conversion of grassland or woodlands to

desertlike conditions

Deforestation

• Human activities strip woodlands of trees– Flooding – Landslides

– Increases atmospheric CO2

– Decreases atmospheric oxygen

• Deforestation– Removal of all trees from a large tract of land

Pollution

• Human activities generate pollutants that kill animals and damage ecosystems

• Pollutant– Natural or man-made substance released into

the environment in greater than natural amounts, and that damages the health of organisms

Acid Rain

• Acid rain– Rainfall contaminated by acidic pollutants– Burns trees, kills fish, leaches nutrients from soil

• Caused by pollutants that combine with water vapor in the atmosphere to form acids – Sulfuric acid from sulfur dioxides from coal-burning

power plants and factories – Nitric acid from nitrogen oxides from vehicles and

power plants that burn gas and oil

Other Sources of Water Pollution

• Pollution from point sources may be identified; dealing with pollution from nonpoint sources is more difficult– Industrial chemicals and heavy metals– Oil from vehicles– Runoff of fertilizers, pesticides, herbicides, and

animal wastes – Sewage and excreted prescription drugs– Sediments

Some Results of Water Pollution

• Bioaccumulation– Concentration of toxins such as mercury as they move

up through the food chain

• Eutrophication– Nutrient enrichment by sewage and fertilizers, resulting

in toxic algal blooms or oxygen depletion

• Turbidity– Clouding of water by sediment runoff, blocking sunlight

and choking animals

The Trouble With Trash

• Human activities generate plastics and other trash that kill animals and damage ecosystems– Chemicals from buried trash contaminate

groundwater– Wastes dumped or washed into the ocean

damage marine ecosystems– Plastics can persist more than 100 years

Air Quality

• Pollution from airborne particles damages respiratory systems of humans and animals– Burning of fossil fuels and industrial processes

• Some pollutants have global effects– CFCs cause thinning of the ozone layer– Rising levels of greenhouse gases contribute to

climate change

The Ozone Hole

• Ozone is a pollutant near the ground, but depletion of the ozone layer is a global threat caused by the use of CFCs– Global agreement to phase out CFC use

• Ozone layer– Atmospheric layer with a high concentration of

ozone that prevents much ultraviolet radiation from reaching Earth’s surface

Global Climate Change

• Climate change caused by rising concentrations of greenhouse gases is another global threat– Results in extremes in rainfall patterns and

drought, increased hurricane intensity

• Global climate change– Global warming and other changes in the current

climate and weather patterns

ACTIVITY #1POLLUTION LAB

Using Kit: Water Pollutants and a Living Organism

Pre-Lab InstructionsPOLLUTION LAB

Determining the effects of water pollutants on a living organism

Examining 6 known water pollutants

Regulatory agencies control pollutant dumping and concentrations in water….. BUT worry about Biological Magnification

Also need to assess positive synergy between pollutants

Pre-Lab InstructionsPOLLUTION LAB

Procedure

Gather all materials (working in groups of 2-3) 6 pollutants labeled A, B, C, D, E, F Depression slide Plastic pipettes Distilled water Microscope

Pre-Lab InstructionsPOLLUTION LAB

Procedure – Part 1

1. Prepare control by placing 2 drops of distilled water in depression slide. Then add 1 drop of organism

2. Use microscope to observe organism in the control conditions3. Place 1 drop of distilled water in 6 depression slides4. Add 1 drop of Bottle A and then 1 drop of living organism5. Start timer and observe the organism under the microscope. 6. Record amount of time it takes to lose ability to swim (form coils)7. Wait 5 minutes – if no changes in movement record a negative result8. Repeat by adding 1 drop of each pollutant (B-F) to the remaining depression

slides and record results.

Pre-Lab InstructionsPOLLUTION LAB

Procedure – Part 1

Bottle A – Silver Nitrate

Bottle B – Mercury Nitrate

Bottle C – Nickel Nitrate

Bottle D – Lead Nitrate

Bottle E – Aluminum Nitrate

Bottle F – Copper Nitrate

Pre-Lab InstructionsPOLLUTION LAB

Procedure – Part 2 (Synergy)

1. Place 1 drop of Pollutant B 4 depression slides2. Add 1 drop of Bottle C and then 1 drop of living organism to first slide3. Start timer and observe the organism under the microscope. 4. Record amount of time it takes to lose ability to swim (form coils)5. Wait 5 minutes – if no changes in movement record a negative result6. Repeat by adding 1 drop of each pollutant (D-F) to the remaining depression

slides(containing a drop of B and record results.