Sequence | Background | Objectives | Materials | Activity | Extensions | Evaluations

TOPIC-TITLE Marine & Aquatic Pollution - Bioaccumulation AUTHOR Gloria Gonzales GRADE SUITABILITY Upper Elementary SCOPE Environmental Science General Science Life Science Marine Science Biology

Sequence Before this activity students should have studied the ecology of an estuary and its importance, including the limiting factors. Students should also understand a food chain. < < go top

Background Summary Estuaries are extremely productive environments. The marsh plants found in an estuary are producers, because they are capable of making their own food. Some of the fish and clams are primary consumers. They cannot make their own food and, therefore, feed on the plants. The birds and other marsh predators are secondary consumers, feeding on the smaller organisms. Bioaccumulation occurs when toxic substances accumulate in higher and higher concentrations from one level of a food chain to the next. < < go top Objectives Students will be able to do the following: Identify limiting factors. Demonstrate bioaccumulation. < < go top Materials A simplified diagram of a food chain (instructions given during activity) Easel and flip chart Green marker for plants, fish, and gull Red marker for pollutant < < go top Activity Using the green marker, make a diagram on the flip chart, overhead, or chalkboard of the three levels of a simple food chain. The producers are marsh grasses; draw several thick blades of grass. The primary consumers are the fish; draw six fish at level two. The secondary consumers are the gulls; draw one large gull at level three. Display the diagram on the easel so everyone may view it. Explain to the students what you have drawn and what the animal shapes represent. Divide the class so eighteen students represent the marsh grass; six students represent fish, and one student will be the gull. Explain that an unknown pollutant has been deposited in the salt marsh. This pollutant has been absorbed by the marsh grass. Plants cannot metabolize/decompose some chemicals so they store them. The plants have absorbed a small amount of the pollutant. Have the students representing the marsh grass come to the front of the room. Use a red marker to draw a small circle on one of the grass blades in the diagram. Each circle represents a small amount of the pollutant. Then, ask the students representing fish to come to the front of the room. Use the red marker to draw a circle around every blade of grass that is eaten (three blades of grass per fish). Finally, point to the gull on the diagram and ask the student representing it to come forward and, using the red marker, draw circles in the gull. The gull will consume all of the fish in the diagram. A total of eighteen circles will be drawn in the gull by the end of the activity. < < go top Possible Extension The students will list possible pollutants in the estuary. The students will investigate possible ways to prevent, reduce, or eliminate chemical pollutants. Research the effects of bioaccumulation in several species (eagles and alligators). Students should report, make a bumper sticker, or write an eco-poem about the animal. < < go top Teacher Evaluation Have students role play the concept of bioaccumulation. Have students identify and explain limiting factors of the estuary. Have students write a report on what bioaccumulation is and how it affects humans. < < go top