The student is expected to: 11B investigate and analyze how organisms, populations, and communities respond to external factors; 12C analyze the flow of matter and energy through trophic levels using various models, including food chains, food webs, and ecological pyramids; 12D recognize that long-term survival of species is dependent on changing resource bases that are limited; 12F describe how environmental change can impact ecosystem stability.

Warm-Up (9/14) Answer the following questions, and explain in a complete sentence why each answer is correct. Name Date Period One difference between parasitism and predation is that parasites a. do very little harm to their hosts. b. keep their hosts alive for a period of time. c. attack the host only from the inside. d. are not very big. An oak tree provides a sparrow a place to build a nest. The nest neither benefits nor harms the tree. What is the name for this type of relationship? a. mutualism b. commensalism c. predation d. parasitism

What happens when humans introduce chemicals intro the environment?

KEY CONCEPT Pollution of Earth’s freshwater supply threatens habitat and health.

Water pollution affects ecosystems. Pollution can put entire freshwater ecosystems at risk.

Biomagnification is the gradual buildup of a chemical in a LIVING ORGANISM.

biomagnification video Biomagnification is the gradual buildup of a chemical in a LIVING ORGANISM. Toxins are consumed by an organism and but not excreted (pooped out). The toxin builds up in an organism’s body. Toxins can’t be broken down by the organism for use. Toxins can affect the development of an organism and its offspring. biomagnification video

Pollutants move up the food chain. predators eat contaminated prey Biomagnification causes accumulation of toxins in the TROPHIC LEVELS of food chain. Pollutants 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. Bald Eagles

Toxins at any tropic level will effect the other levels. The tiny primary consumers eat a little bit of the toxin. Most toxin Least toxin The secondary consumers eat many of the 1st consumers so they eat more of the toxin The tertiary consumers eat many of the 2nd consumers so they eat even more of the toxin At every level the amount of toxin increases! What would a pyramid for this look like?

Common Toxins demonstrating Biomagnification: DDT (pesticide) Methyl Mercury PCB’s

DDT accumulates in living tissue, particularly in fat tissue Case Study: DDT DDT is a pesticide that was widely used until being banned in the U.S. in 1972 DDT accumulates in living tissue, particularly in fat tissue High concentrations in some bird species caused failure of eggs by thinning the shells

What makes methylmercury so dangerous? Case Study: Methyl Mercury What makes methylmercury so dangerous? Methylmercury is rapidly taken up but only slowly eliminated from the body by fish and other aquatic organisms, so each step up in the food chain (bio)magnifies the concentration from the step below. Bioaccumulation factors (BAF's) of up to 10 million in largemouth bass have been reported for the Everglades. Fish-eating birds, otters, alligators, raccoons and panthers can have even higher bioaccumulation factors.

Mercury Health Effects

PCBs, or polychlorinated biphenyls, are a group of man-made chemicals. Introduced in 1929 and widely used in electrical transformers, cosmetics, varnishes, inks, carbonless copy paper, pesticides and for general weatherproofing and fire-resistant coatings to wood and plastic. The federal government banned the production of PCBs in 1976 PCBs can effect the immune system, fertility, child development and possibly increase the risk of certain cancers Case Study: PCBs

Let’s try this: Let’s say, for example, that each piece of plant material has one microscopic drop of methyl mercury. One insect eats 25 pieces of plant material, that would mean that each insect would have _______ microscopic drops of methyl mercury in its body. If one small fish needs 10 insects to live, then one fish would have _____ microscopic drops of methyl mercury. What about you and me? Lets say we eat 1 small fish a day for 3 days. We would collect total of ______ drops of methyl mercury in our body over the 3 days. This is how biomagnification works! Which organism is most affected?

http://oceanexplorer. noaa. gov/edu/learning/player/lesson13/l13la1 http://oceanexplorer.noaa.gov/edu/learning/player/lesson13/l13la1.html

Closure Answer the following question in a complete sentence: Name Date Period In an ecosystem poisoned with mercury, why is there more mercury in a tertiary consumer than a producer? Tertiary consumers have more mercury poisoning in some ecosystems because… Scale from 1-10