Ahealthy 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.

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.

The zone your looking for is the intertidal zone.