Q9. As you saw in \"DO or Die\", fish are sometimes lost from lakes as eutrophic
ID: 85502 • Letter: Q
Question
Q9. As you saw in "DO or Die", fish are sometimes lost from lakes as eutrophication occurs. Given what you've learned in this lab about why these fish die-offs occur, which of the following might help maintain the entire ecological community as phosphorus concentrations increase?
Installing aerators that increase the oxygen concentration in the water
Periodically adding more algae to the lake throughout the year
Adding nitrogen to balance the increase in phosphorus and promote algal growth
Trawling the lake with specialized nets to filter out extra zooplankton
Explanation / Answer
The fish die-offs occur due to eutrophication because of increased phosphorus levels,the phytoplankton grow under optimal conditions. When phytoplankton reach their maximum population density and began to die. In a chain link process,the other organisms like bacteria and algae will also accumulate. Finally as there is no access to sunlight, a dead zone is created and the other organisms like fish were killed. And coming to the solutions given for eutrophication given in the question.
1) Installing aerators that increase the oxygen concentration is the best one because the water quality will be increased and hence the fish growth and health were improved.
2) Perodically adding more algae - The problem of eutrophication is with increased algae, then adding of more algae will not be a solution and instead it increases the problem.
3) Adding nitrogen to balance phosphorus - This one is also not a solution for reducing the eutrophication because increases levels of nitrogen also leads to further eutrophication only but it does'nt maintain the ecological community
4) Trawling the lake with extra zooplankton - This is entirely a wrong one because we have to add zooplankton, not remove them from the lake. See, we are facing a problem with incresed phytoplankton levels and their dead remnants. If we increase the levels zooplankton, then only there will be a possibility of reducing the increased phytoplankton levels by consuming them and make the water clean.
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