A lake has this chain: phytoplankton, zooplankton, small fish, a larger fish, a gull…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A lake has this chain: phytoplankton, zooplankton, small fish, a larger fish, a gull.
- Which organism is at T1?
- What are the zooplankton called?
- Which trophic level is the larger fish, and what is it called?
- Which level is the gull?
Need a reminder? The key ideaShow
The trophic levels are T1 producers, T2 primary consumers, T3 secondary consumers and T4 tertiary consumers. In a web, a species can sit on more than one level. The standing crop is the biomass or the number of organisms in a unit area, and dry weight is the more accurate measure.
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. (a) The phytoplankton are at T1. They are the producers.
Step 2. (b) The zooplankton are at T2. They are the primary consumers.
Step 3. (c) The small fish are at T3 (secondary consumers). The larger fish are at T4, so they are tertiary consumers.
Step 4. (d) The gull is at T5, the fifth trophic level.
Answer: (a) phytoplankton; (b) primary consumers; (c) T4, tertiary consumers; (d) T5.
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