Ecology

1. Ecology

2. Energy Flow in an Ecosystem • Trophic Levels • Ecologists use food chains & food webs to model the flow of energy through an ecosystem • Each feeding level within a food chain/web = Trophic level • 3 Major Trophic Levels • 1. Producers • Plants, Plankton, Algae • Make organic material from inorganic material • Sunlight, carbon, oxygen, nitrates, water

3. Energy Flow in an Ecosystem • Remaining Trophic Levels • 2. Consumers • Get organic material from other living tissues • 3 Types: • Herbivore: • Eats only producers • Ex: Cow, grasshopper, rabbit • Carnivore: • Preys on other heterotrophs • Ex: Wolves, lion • Omnivore* • Eats both plants & animals • Ex: Bears, humans, mockingbirds

4. Energy Flow in an Ecosystem • Remaining Trophic Levels • 3. Decomposers • Fungi (mushrooms), bacteria • Breakdown dead organic material and returns inorganic material back to the soil

5. Invasive Species • Asian Long Horned Beetle • Sighted in Worcester, MA • Kills trees • Popular, Willow, Elm • Beetle reproduces inside the tree • Larvae tunnel through and eat the tree • Tree crumbles • Native to Asia/Japan where there is a natural predator • Has no natural predator in the United States

6. Invasive Species • Asian Long Horned Beetle

7. Invasive Species • Snakehead Fish • Native to Asia • Many different species of the Snake Head Fish • Some are huge and very aggressive • Get caught in fish nets  Attack fisherman • Sold as pets in the United States • Pet stores started purchasing smaller versions of this fish • People who could not keep them  dumped them into ponds • No predator in the United States • Eat everything that lives in a pond (top of the food chain) • Deplete entire food source within the pond and then MoVe on to another pond • Shimmy across land  primitive lung (in addition to gills)

8. Invasive Species • Snakehead Fish • Evolutionary Advantage • Can breath oxygen • Within the air (primitive lung) AND • Within the water (gills) • Swim and move across land

9. Invasive Species • Snakehead Fish

10. Pollution • Pollution • Threatens biodiversity and global stability • Changes the composition of air, soil, & water • Many types… • Human-made chemicals, not found in nature, are being discovered in food webs • Pesticides  DDT (dichloro-diphenyl-trichloroethane) • Industrial chemicals  PCBs (polychlorinated biphenyls)

11. Biological Magnification • Biomagnification: • Increasing concentration of toxic substances in organisms as trophic levels increase in a food chain/web • Carnivores at the higher trophic levels seem to be most affected • Examples of toxic substances accumulating in food webs: • DDT • Mercury • PCBs

12. DDT • Highly effective pesticide • Used from the 1940s to the 1970s to control crop-eating and disease-carrying insects • However, it caused the eggshells of fish-eating birds to be fragile and thin  death of the developing birds • May have played a role in the near extinction of the bald eagle & peregrine falcon • Once these toxic effected were discovered, the use of DDT was banned in some parts of the world

13. Mercury • Heavy metal found in the ocean • Water  Algae  Bigger Fish (Tuna, swordfish)  Human • Pregnant women should not eat tuna or swordfish due to the accumulation of the mercury in these fish • Link between autism & mercury

14. PCBs • Manufactured from 1929 until banned in 1979 • Range of toxicity • Cancer • Adverse health effects on the immune, reproductive, nervous, & endocrine systems • Hundreds of industrial & commercial applications • Electrical • Heat transfer • Hydraulic equipment • Plasticizers in paints, plastics, & rubber products

15. Eutrophication • Another form of water pollution • Destroys underwater habitats for fish and other species • Fertilizers, animal waste, sewage (rich in nitrogen & phosphorus) flow into waterways • Resulting in extensive algae growth • Algae use up the oxygen supply during their rapid growth & after their deaths during the decaying process • No oxygen in the water = other organisms in the water suffocate