Prelab questions
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| Ecosystem lab: Biological magnification of DDT at each trophic level Name: _______________
Date: _________________ Period: _______________ Prelab questions Write definitions of the following terms. Food chain: Producer: Consumer: Autotroph: Heterotroph: Introduction DDT, a powerful insecticide, was widely used in the mid 1900s in the United States, but its harmful effects on the environment made people stop using it in 1972. DDT remained in organisms’ bodies without being broken down. Large carnivorous birds especially were vulnerable to DDT and laid eggs with thin shells because of the effects of DDT (Solomon, Berg, and Martin, 2008). A food chain shows “energy flow in an ecosystem” (Solomon, Berg, and Martin, 2008, p. G-17). In other words, it shows which organism consumes which organism and which organism decomposes which organism in a linear way. A food chain usually has producers, consumers of different levels, and decomposers. Producers are usually autotrophs and use photosynthesis to produce energy. Consumers feed on producers or other consumers and are heterotrophs. A trophic level is each level or step of an organism in terms of its role (producers, consumers, secondary consumers, etc.) in a food web (Solomon, Berg, and Martin, 2008). You will be given the data of DDT concentrations of organisms at each trophic level in the same food chain. Your job is to draw a graph based on the data and analyze the results. Hypothesis Will the DDT concentration increase or decrease at each trophic level of a food chain? (In other words, will consumers have more DDT concentration than producers?) ______________________________________________________________________________________________________________________________________________________________________________
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In a study by Woodwell, Wurster, and Isaacson (1967), scientists measured DDT residues (DDT that remains in an organism’s body) in different organisms at different trophic levels. This study was done in Long Island, New York. They used gas chromatograph to measure the amount of DDT in thirty-nine plants and animals in the area. (Table 1 shows the data of five organisms that are in the same food chain.) Observation/data Table 1. DDT concentrations in samples
Draw arrows between the pictures of organisms below to create a food chain. Label each organism with a proper trophic level (i.e. producers and consumers; herbivores are primary consumers, and carnivores are secondary or tertiary consumers. Animals that eat secondary consumers are tertiary consumers.)  Plankton:
 Shrimp:
 Atlantic needle fish:
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