Respuesta :
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.
B.) It decreases oxygen in the water, creating a toxic environment.