A pesticide washes into a lake from nearby farms…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A pesticide washes into a lake from nearby farms. Scientists measure it in the water, in tiny plankton, in small fish, in big fish and in fish-eating birds. Predict where they find the highest concentration, and explain why.
Need a reminder? The key ideaShow
Energy enters from the Sun; plants capture about 1% of it. About 10% of the energy passes from one trophic level to the next, and the rest is lost, mostly as heat, so energy flows one way and chains are short. Non-biodegradable chemicals build up along a chain (biological magnification), most at the top.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Not broken down. The pesticide is not biodegradable, so it stays in the bodies of living things.
Step 2. Building up. Plankton take it up from the water. Small fish eat many plankton, big fish eat many small fish, and birds eat many big fish.
Step 3. The result. At each step the chemical is collected from many bodies, so it becomes more concentrated.
Answer: the highest concentration is in the fish-eating birds, at the top of the chain, by biological magnification.
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