Principles of Ecology

Describe the causes and effects of biological magnification Outline the strategies used by conservation biologists to conserve Earth’s biodiversity. Identify and analyze historical trends in global carbon dioxide levels and temperature. Discus the relationship between anthropogenic activity and climate change.

Remember the biomass pyramid? Food that is consumed is generally broken down and used for energy and/or building materials by consumers.

Remember the biomass pyramid? Some chemicals that humans release into the environment cannot be broken down and cannot be excreted by the organisms that ingest them. These chemicals enter the food chain at the level of the primary producers. Chemicals

The effect is called biological magnification (or bioaccumulation). These chemicals enter the food web at the lower trophic levels and are passed up through consumers. The effect of the chemicals is magnified at higher trophic levels. Lower concentrations at lower trophic levels may be harmless, but higher concentrations at higher trophic levels can be harmful. Chemicals

DDT is used to kill insects, particularly mosquitos. The biological magnification of DDT can lead to egg shell thinning in birds of prey

Other chemicals that accumulate (are magnified) through successive trophic levels PCBs (polychlorinated biphenol) Used in coolant fluids Mercury released through various human processes, including metal production

Rachel Carson and Silent Spring – the foundation of the environmental movement Rachel Carson and Silent Spring – the foundation of the environmental movement What did Rachel Carson mean when she spoke of the balance within nature? What are some effects of human technology on local ecosystems? Is it possible for human to have no effect on our environment?

The Greenhouse Effect – Is it a bad thing? Without the greenhouse effect, life on earth would not be possible.

Discussion question – list some sources of atmospheric carbon (CO2) Which sources are natural and which sources are anthropogenic?

Due to the increased burning of fossil fuels and other human activities, t he concentration of atmospheric CO 2 has been steadily increasing. More CO2 enhances the Greenhouse Effect.

How might climate change affect food chains and evolutionary adaptations?

There have been 5 major extinction events in the history of earth. Are we initiating the 6 th major extinction due to human causes?

Some famous North American Extinct Species Passenger Pigeon - hunting - deforestation Heath Hen hunting Carolina Parakeet - feathers for hats - killed as pests - forest habitat lost to agriculture

Other North American species Steller’s Sea Cow - hunted to extinction Utah Lake Sculpin Agricultural pollution Xerces Blue - Larval form (caterpillar) lost a symbiont ant when exotic ants were introduced to San Francisco and out-competed the native ants.

Current threats to species Habitat loss, fragmentation, destruction, and pollution Overharvesting/hunting and illegal poaching Exotic species introductions Cascading effects within food webs Climate change

How have we reacted to the Biodiversity Crisis? Endangered Species Act of 1973: Endangered Species Program

As a response to a number of disappearing and declining species in the United States, the Endangered Species Act (ESA) was created in 1973.

Endangered species – any species which is in danger of extinction through all or a significant part of its range. Endangered species in Colorado – Black footed Ferret

Threatened species – any species which is likely to become an endangered species within the foreseeable future throughout all or a significant part of its range. Threatened species in colorado – River OtterRiver Otter

A threatened species is the Maned wolfManed wolf Native to grasslands in South America What may have caused the maned wolf to become a threatened species? What could you do to protect the maned wolf from becoming endangered or extinct?

How has the international community reacted to the Biodiversity Crisis? International Union for Conservation of Nature and Natural Resources

A way to control further loss of species is to identify hot spots of biodiversity: an exceptional concentration of endemic species and a large number of endangered and threatened species. Terrestrial biodiversity hot spots Equator

Indicator species tell us when something is wrong in the environment.

Review and Discussion: What are some ways in which humans impact the environment and therefore threaten biodiversity? What are some things that you can do to protect biodiversity and prevent the next mass extinction from occurring due to anthropogenic causes?