Phosphorous and other chemicals are mined from earth's crust in order to manufacture products. phosphorous is used to produce fertilizers. when it rains over farmland, the excess fertilizers enter runoff. the runoff flows into rivers, lakes, and bays, where the fertilizer causes the local population of algae to increase rapidly in size. how do algae blooms impact aquatic ecosystems? a. they block light from penetrating deep within the water, thus leading to a dramatic fall in the water's temperature. b. they cause the water in the ecosystem to increase in acidity, thus killing most of the ecosystem's bacteria. c. they lead to the deoxygenation of the ecosystem, thus killing fish and other organisms in the ecosystem. d. algae blooms have little to no impact on aquatic ecosystems.