This document discusses trophic levels and biomass transfer in a Mono Lake ecosystem food chain. It notes that only 10% of energy is transferred from one trophic level to the next. It then asks a series of questions about placing beads on a stem to represent the biomass at each trophic level needed to produce 1 kg of biomass at the next level, starting from algae and moving up through brine shrimp, brine flies, and California gulls. It also asks how adding coyotes to the ecosystem would affect the biomass needs at each level.

1. 10% Rule Only 10% of the energy consumed at one trophic level is available as food for the next trophic level

2. Dark Green Benthic Algae Light Green Planktonic Algae Red Brine Shrimp Black Brine Flies Gray California Gull Each bead represents 1 kg of biomass in Mono Lake Ecosystem

3. What is represented by the red bead on the stem? Brine shrimp have to eat in order to survive. What do brine shrimp eat? Using the 10% rule, how many beads should be put on the stem to represent the food eaten by the shrimp to produce 1 kg of shrimp mass.

4. What do California gulls eat? How could you show how much biomass went into producing a kilogram of California gull biomass?

5. Does a healthy ecosystem produce the same amount of biomass at each trophic level? Which trophic level has the largest biomass? Why? If brine shrimp eat 10 kg of algae to produce 1 kg of brine shrimp biomass, where does the other 9 kg of go? What happens to an ecosystem if one population fails?

6. If a coyote moved into the ecosystem, how could you show a kilogram of coyote biomass in our bead ecosystem?

7. If a 20 kg coyote ate only Wilson’s phalaropes, how much planktonic algae would the Mono Lake ecosystem have to produce to support the coyote?

8. 20 kg coyote 200 kg Wilson’s phalarope 2000 kg brine shrimp 20,000 kg algae