Coastal water quality has been an important issue on Cape Cod for several years. In coastal bays and estuaries, runoff of nitrogen has had a serious impact on the health of these important ecosystems. Nitrogen acts as a fertilizer and can cause algae blooms that eventually result in a reduction of animal life.
This process of excess nitrogen and the rapid growth of certain algae species is called eutrophication. The nitrogen comes from a variety of sources, including septic systems, lawn fertilizers, and the atmosphere. When a single species of algae suddenly increases in population, such as the sea lettuce (Ulva lactuca), it blocks sunlight to other plants including the ecologically important eelgrass (Zostera marina). Bacteria are responsible for the decomposition of this algae. This process can happen very quickly. For example, sea lettuce only lives for a few weeks. During decomposition the bacteria consume oxygen, creating low dissolved oxygen concentrations for invertebrates and fish. Crabs, shrimp, mollusks, and small fish can be killed under these conditions. There is even some evidence that the harmful red tide organism Alexandrium may increase due to nitrogen loading.
To see this process in the extreme one needs to visit the Gulf of Mexico. Amazingly, a large “dead zone” exists for over 7,000 square miles. The recent oil spill there only made matters worse. However, this has been a problem for many years. Agricultural and industrial wastes have been pouring into the Gulf creating this massive hypoxia situation.
Though this is an extreme and unsettling example, conditions on Cape Cod must also be monitored. Many systems have been adversely affected by nitrogen loading including Buzzards Bay, WaquoitBay, and the Three Bays Estuary in Barnstable. As long as the Cape remains a popular destination to visitors and homeowners, nitrogen loading will remain an issue. Development along the coast is directly linked to these higher elevations of nitrogen.
The solution to this problem will be costly. Controlling the volume of nitrogen into coastal waters will inevitably require more advanced wastewater treatment, including additional facilities. Whether this is in the form of a large municipal sewage treatment plant, or smaller, neighborhood structures remains to be seen. Experimental and alternative systems have been explored for many years, but they remain unlikely on a large scale. Of course, the acquisition of open space for conservation has always been a very cost effective means of protecting water. And towns can continue to pass new zoning regulations that minimize the effects of development. There is no doubt that the problem of nitrogen loading must be addressed if the Cape is to protect its coastline.
Copyright Gil Newton 2009 Thanks to Chris Dumas for logo image.