Question

food web chain please answer following questions

1. Some organisms are specialists and dependent on one food source while others are generalists and rely on many different food sources. Which is more able to withstand changes in the ecosystem, specialists or generalists and why is that?

2. What do you think would happen if an oil spill occurred that killed off most of the phytoplankton and zooplankton?

3. The pesticide DDT is a persistent organic pollutant which accumulates in the fat tissues and negatively affects organisms at higher trophic levels via biomagnification up the food chain.  What might happen if a man-made pesticide like DDT was added to your ocean food web?

4. How are detritivores (decomposers) important to an ecosystem?

Answer 1

Ans1- Generalists will be more able to withstand changes in the ecosystem than specialists. this is because if there is a drastic change in ecosystem, and the food present earlier are not available any more. Than it will be difficult for specialists , because they need particular food to eat, whereas generalists will eat any food that will be available.

Ans 2-The loss of phytoplankton is a huge problem for marine food chains, because every creature in the ocean either eats phytoplankton or eats zooplankton that depend on it. If their numbers start to decrease, the populations of these species would drop as well.

Ans 3-DDT, like other organochlorine pesticides enter the marine environment mainly through inputs from water and air, as a result of their use in agriculture

DDT has a very high tenancy towards biomagnification. When in a simple ecosystem the background concentration is equal to 1, then zooplankton can accumulate concentrations of 13.000, small fish species concentrations of 170.000, large fishes up to 670.000 and finally birds will accumulate concentrations up to 8.300.000. DDT has been found in all marine ecosystems, including the Antarctic and the deep sea. It can be found in all components of the marine food web.DDT affects the central nervous system of insects and other animals. This results in hyperactivity, paralysis and death.

Ans4- Detritivores and decomposers contribute to the breakdown of all of the dead and decaying material in any ecosystem. In this way they play an important role in the cycling of nutrients and are an essential part of most biogeochemical cycles, such as the carbon cycle, nitrogen cycle and the phosphorus cycle.These organisms play an important role in all ecosystems by getting rid of decaying organic matter left behind by other organisms.