HUMAN INFLUENCES ECOLOGY

TOPICS 1.Biosphere Issues a.Global Warming b.CFCs c.UV Radiation 2.Ecosystem Issues a.Biomagnification b.Biodiversity Loss c.Alien Species 3.Conclusion a.Precautionary Principle b.Local change

THE GREENHOUSE EFFECT © Oceanworld 2005 Robert R Stewart

BIOSPHERE ISSUES GLOBAL WARMING Video Case Study

THE LAYERS OF THE ATMOSPHERE The troposphere is the part of the atmosphere in the biosphere The stratosphere contains the ozone layer The stratosphere is also a zone of warm air that keeps a lid on the troposphere. It does not mix with the upper atmosphere © Windows to the UniverseWindows to the Universe © Text 2007 Paul Billiet ODWSODWS

THE OZONE LAYER

SUNLIGHT ENERGY IN THE ATMOSPHERE © Windows to the UniverseWindows to the Universe

CHLOROFLUOROCARBONS (CFCS)

THE OZONE LAYER STOPS 99% OF UV RADIATION

OZONE

BIOSPHERE ISSUES CFCS CFCs are chlorofluorocarbons These are molecules used in: Refrigerators Air conditioners Fire extinguishers Propellants in aerosol sprays

BIOSPHERE ISSUES CFCS It was believed that they diffused harmlessly into the stratosphere where they were broken down by sunlight. This is true, BUT… We now know that in the process of breaking them down, a chlorine atom is produced. Chlorine is very destructive to the ozone layer. Chlorine reacts with ozone molecules and breaks it apart into oxygen, which cannot turn back into ozone. One chlorine atom can destroy 100,000 ozone molecules.

THE EFFECTS OF UV RADIATION The main effect of UV radiation on living tissues is its ability to alter DNA. This can eventually lead to skin cancer.

SPECIFIC EFFECTS Skin cancers Carcinomas (relatively minor) Melanomas (dangerous) Eye issues Cataracts (lens becomes less transparent) Growths Phytoplankton – very sensitive to UV light Plants – lower crop yields Nitrogen-fixing bacteria – low tolerance to UV light

THINK, PAIR, SHARE a. Are CFCs that big of a problem? Why or why not? b. Propose a solution to this problem.

TOPICS 1.Biosphere Issues a.Global Warming b.CFCs c.UV Radiation 2.Ecosystem Issues a.Biomagnification b.Alien Species c.Biodiversity Loss 3.Conclusion a.Precautionary Principle b.Local change

BIOMAGNIFICATION Another side-effect of our contaminating the environment is biomagnification. Once toxins are in the environment, they can be ingested or absorbed into organisms. If an organism takes in small quantities of a toxin without breaking it down or excreting it, it accumulates in its body. This is called bioaccumulation.

BIOMAGNIFICATION As these toxins travel up the food chain, they become more concentrated at each trophic level. This is called biomagnification.

EXAMPLE - DDT DDT is the best known organic pesticide (it was used to kill insects).

EXAMPLE - DDT It is hydrophobic, so it won’t dissolve in water. This means it stays where its sprayed for a long time. This also means that it cannot be excreted in urine. It takes 2-15 years for it to break down.

DDT IN A FOODCHAIN

TEXTBOOK EXAMPLE P Read the section entitled, “Toxins in the Environment” 2.Make a sequence of events chart to show the progression of DDT in the environment.

DATA-BASED QUESTIONS

CLOSURE “Man has lost the capacity to foresee and to forestall. He will end by destroying the earth.” Albert Schweitzer

INVASIVE SPECIES Invasive (alien) species are non- native, introduced species that affect native organisms, change ecosystems, and cause lots of damage! They get introduced into an ecosystem, either intentionally or accidentally. They thrive to the detriment of other species. The Cane Toad

HUMAN INFLUENCES IN ECOLOGY TOPICS 1.Biosphere Issues a.Global Warming b.CFCs c.UV Radiation 2.Ecosystem Issues a.Biomagnification b.Alien Species c.Biodiversity Loss 3.Conclusion a.Precautionary Principle b.Local change

BIODIVERSITY 1.What is biodiversity? 2.How is biodiversity calculated? 3.Causes of Biodiversity Loss 4.Reasons for Conservation

BIODIVERSITY Biodiversity refers to the variety of life on Earth. It includes: the variety of species the genetic variations within species the different types of ecosystems and biomes the species live within. Definition of species? A group of organisms that can interbreed and produce fertile offspring.

BIODIVERSITY BY THE NUMBERS The reported number of species on the planet varies widely. Traditionally the number is somewhere between 5 and 30 million. Approximately 1.75 million species have been formally described and given official names.

NUMBER OF DESCRIBED SPECIES ON EARTH SpeciesNumber Bacteria4,000 Protists (algae, protozoa)80,000 Animals – vertebrates52,000 Animals – invertebrates1,272,000 Fungi72,000 Plants270,000 Total described species1,750,000 Source: UNEP/Global Environment Outlook (Ref 3)

Insects comprise more than half of all known species on the planet!

HOW DO WE CALCULATE BIODIVERSITY? Before biodiversity is calculated, populations must be counted. How are populations counted? We would take samples! Quadrant Sample Transect Line Sample

HOW DO WE CALCULATE BIODIVERSITY? Once population density is determined… Scientists calculate diversity by using the Simpson diversity formula. It takes into account the number of different species within the community and the number within each species. Definition of community? A group of different populations in the same area.

SIMPSON DIVERSITY FORMULA N = the total number of organisms of all species n = the number of organisms of a particular species D = the diversity index The value of D represents how diverse a community is. The higher the number, the more diverse an area is. D =

G.3.1 CALCULATE THE SIMPSON DIVERSITY INDEX

BIODIVERSITY LOSS Biodiversity is being influenced by humans.

WITH YOUR PARTNER Come up with 3 specific human- induced causes of loss of biodiversity.

What’s causing loss of biodiversity? 1. Overexploitation (over hunting, clearing of forests)

What’s causing loss of biodiversity? 2.Habitat Destruction

What’s causing loss of biodiversity? 3. Introduction of alien species

What’s causing loss of biodiversity? 4. Pollution

What’s causing loss of biodiversity? 5. Climate change

With your table partner, discuss… Come up with 2 reasons why biodiversity should be conserved? Most people think the MAIN reason why biodiversity should be conserved is just for “beauty” reasons. However….there are other important reasons too!

REASONS FOR CONSERVATION OF BIODIVERSITY 1.Ethical Reasons All life has value. Destroying ecosystems denies future generations. “Extinction is forever” We are not the only ones here.

REASONS FOR CONSERVATION OF BIODIVERSITY 2.Ecological Reasons A loss of biodiversity will affect ecosystems. Food webs will be altered. The effects will have a domino effect. The recycling of nutrients will be altered. Tropical rain forests cover about 7% of the Earth’s land surface, but they contain more than 50% of the known species.

REASONS FOR CONSERVATION OF BIODIVERSITY 3.Economical Reasons Food sources Pharmaceutical companies are continually researching new medicines from wild species. Some countries depend on their “wildlife” to attract tourists.

REASONS FOR CONSERVATION OF BIODIVERSITY 4. Aesthetic Reasons

CLOSURE Please fill out the Exit Ticket a.Define biodiversity. b.Name two reasons why we should conserve biodiversity. c.If we continue consuming paper products at our current rate, the rainforest will be extinguished in 120 years. Are you willing to sacrifice your “need” for paper products in order to conserve biodiversity in the rainforest? Explain your thinking.

BELLWORK What are two ways that scientists take samples of populations? Hint: Think of the “mini-lab” we did outside.