On May 23rd, Pamela Wood of the Annapolis Capital covered how excessive nitrogen flowing into Chesapeake Bay is degrading its waters. Her article focuses on the recent commitment by the states within the Bay's watershed to reduce nutrient inputs in an effort to improve water quality but inaccurately describes how nutrients contribute to oxygen depletion and the ability of the system to recover.
Nitrogen is a critical nutrient for plants and algae and supports many basic processes in water-based ecosystems. Problems arise when too much of it enters waterways from sewage effluent, runoff of fertilizers used in agriculture and on lawns, and from the atmosphere due to burning of fossil fuels. In waters such as the Chesapeake, the nitrogen degrades water quality and ecosystem health by causing excessive plant and algal growth.
The article clearly describes that the seven states within the watershed recognize the need to reduce nitrogen levels in the Bay and explains the much-needed steps they will take to achieve the reduction in two years. For instance, Maryland will reduce nitrogen levels by 7 percent through better controls on coal-burning generating stations, agricultural practices and sewage releases.
I have two points to raise about the article.
The first is the description of how nitrogen affects aquatic systems like the Chesapeake Bay. It is true that nitrogen is a fertilizer that promotes plant and algal growth. But, the dead zones (areas of low oxygen) mentioned in the article result from decomposing dead plants, algae and organic wastes.
Plants and algae themselves do not “suck life sustaining oxygen from the water.” When they are alive, they produce oxygen that sustains other aquatic life. It is after they die and begin to decay that oxygen levels plummet, as the bacteria that degrade the dead material suck up the oxygen. The oxygen can quickly drop to intolerable levels for fish and other aquatic organisms.
My second point relates to how Ms. Wood describes nitrogen reduction targets. More specifically, she writes that reducing 175 million pounds of nitrogen is what is needed to “not screw up the ecosystem too badly.”
I think it is important to understand that restoring ecosystem health is possible for Chesapeake Bay.
Lake Erie is a classic example of a success story. State and provincial governments and the
International Joint Commission worked together to reduce
eutrophication (excessive plant and algal growth) by decreasing nutrient inputs and spurring subsequent recovery of this large watershed system.
In this case, the culprit was phosphorous, but the end goal was the same. Fortunately systems can recover quickly when nutrient inputs are controlled, as the states surrounding the Chesapeake Bay are willing to do.
