Question

A healthy environment depends on biogeochemical cycles maintaining a balance of input and output. High levels of nitrogenous compounds in the waterways can cause an algal bloom. How does an algal bloom affect a marine ecosystem?
A.) It decreases the carbon dioxide in the water, creating a toxic environment.
B.) It decreases oxygen in the water, creating a toxic environment.
C.) It increases the carbon dioxide in the water, stimulating plant growth.
D.) It increases the oxygen in the water, stimulating plankton growth.

Answer 1

I think the correct answer would be option B. An algal bloom would affect a marine ecosystem by decreasing the oxygen present in the water thus creating a toxic environment for the aquatic organisms. Algal bloom is a condition in an aquatic system where there is a rapid increase in algae. This happens as a result of excess nutrient present in the system due to fertilizer or wastewater runoff. The presence of too much algae would cause a decrease in the dissolve oxygen level in the waters which would affect the aquatic organisms especially those with low tolerance of having low dissolved oxygen.