Question

1. Killer whales feed on whales and are on the fourth trophic level. How much first level biomass would be required to produce a 10-metric ton killer whale? answer: 1000 metric ton first level biomass.

1. How much Blue whale could have been produced from this same mass if it fed at the second trophic level?

Answer 1

​​​​​​In my opinion the answer to the first part of the question is wrong.

Answer should be 10,000 metric ton and not 1000 metric ton because only then will the biomass of 10 metric ton(1killer whale) be available at FOURTH trophic level.(We know that Only 10% of the energy is available at the next higher level.).

Now considering 10000 metric ton of biomass at the First level, 10 % of this will be 1000 metic ton. So at second level 1000 metric biomass will be available.

Now since 1 killer shark= 10 metric ton

We will have at second level = 1000 ÷ 10 =100 killer sharks

Similarly in case we are given 1000 metic ton biomass at level 1 ,then in that case we will have biomass of 100 metric ton at second level equal to 10 killer sharks.