Much of the earth’s land area is covered by grasslands that are too dry to cultivate crops but capable of supporting grazing animals (bison, antelope, cattle, sheep, etc.) on a sustainable basis. Humans are incapable of effectively digesting grass. On the dry grasslands, eating at what trophic level would produce the most food for humans? 2. Large predatory marine fish (ex: tuna, swordfish, marlin, shark, etc.) usually eat at the third through seventh trophic levels. Is it efficient for humans to rely heavily on these species as food sources? Why or why not?
Background
A trophic level, or feeding level, is made up of all the organisms whose energy source is the same number of consumption steps from the sun in a given ecosystem. The trophic level of plants or producers is 1, while that of herbivores is 2 and that of animals that eat herbivores 3. Higher trophic levels can exist for animals even higher on the food chain. In this exercise, you will compute numerical values for human energy needs based on diets at different trophic levels.
In this case study the owner of a farm raises soybeans and chickens. Grasshoppers feed on the farmers soybeans, and are in turn eaten by the chickens. Humans can, though rarely do, eat grasshoppers for sustenance. Humans can also eat soybeans. For the purpose of this exercise, make the following assumptions:
- A human requires 1 chicken/day
- There are 365 days/year
- 1 chicken eats 25 grasshoppers/day
- 1 grasshopper requires about 30 g of soybeans/year
- 1,000 grasshoppers have a mass of 1 kg
- 1 human requires about 600 grasshoppers/day
- Dry soybeans have about 3.3 cal/g
- There are 1,000g/kg
- A typical human requires 3,000 cal/day
1. Much of the earth’s land area is covered by grasslands that are too dry to cultivate crops but capable of supporting grazing animals (bison, antelope, cattle, sheep, etc.) on a sustainable basis. Humans are incapable of effectively digesting grass. On the dry grasslands, eating at what trophic level would produce the most food for humans?
2. Large predatory marine fish (ex: tuna, swordfish, marlin, shark, etc.) usually eat at the third through seventh trophic levels. Is it efficient for humans to rely heavily on these species as food sources? Why or why not?
Trending now
This is a popular solution!
Step by step
Solved in 3 steps
