Final answer:
Large amounts of nitrogen and phosphorous in the Chesapeake Bay lead to eutrophication and the formation of dead zones due to the depletion of dissolved oxygen caused by excessive algae growth and decay.
Step-by-step explanation:
When large amounts of nitrogen and phosphorous flow into an ecosystem such as the Chesapeake Bay, the initial response typically involves the exacerbation of eutrophication. This process occurs as these nutrients cause excessive growth of algae and microorganisms, which after dying begin to decay. The decay process consumes the dissolved oxygen in the water, leading to a condition known as hypoxia, or low-oxygen areas, which are harmful to aquatic life. This can result in the creation of “dead zones”, where the level of dissolved oxygen is so low that fish and other marine life cannot survive, leading to mass die-offs.