Do you like seafood? I sure do – crab legs, crab dip. It’s all good. Some of these crabs that I love to dine upon come from the Chesapeake Bay. However, there’s a problem with this, these little things called phytoplankton are threatening to destroy the crab population from which I get my seafood dinners. Simply as microscopic water organisms, phytoplankton aren't much of a threat, but a study by William Reay, published in the Journal of Coastal Research, shows that phytoplankton are amassing in such great concentrations within the York River estuary that they are becoming a danger for the entire ecosystem. This accumulation of phytoplankton is due to several factors.
In order to deal with any problem, there must be research. Beginning his study by taking measurements on the sediment levels within the estuary, Reay’s team determined that most of the sediment in the York River came from agricultural runoff, with some also coming from erosion of the shoreline. Sediment is merely particles of rock, dirt, and sand that have been weathered off of the mainland by water and carried into the estuary. The source of this estuary’s sediment is significant because the source of the sediment determines which nutrients are being introduced into the estuary. With most of the sediment coming from farm runoff, most of the nutrients are as well. Nutrients from farm run off stem largely from chemical fertilizers and manure. Farmers generally use phosphorous and nitrogen based fertilizers to stimulate crop production, so it makes sense that those are the two most prevalent nutrients found within the York River estuary.
After determining the river’s nutrient composition levels, Reay studied their trend overtime, comparing them to phytoplankton levels. As you might have guessed, phytoplankton levels were at their highest when the levels of phosphorus and nitrogen were at their highest. For you math people, they had a high correlation. With more nutrients to thrive on, the growth of the phytoplankton population rapidly increased. This is not a good thing because extreme concentrations of phytoplankton cause a number of issues that lower the overall water quality of the estuary. These microorganisms bring with them large algal blooms that are harmful to the environment. The algae absorb all of the oxygen in the estuary, starving the other inhabitants of the river of oxygen that they depend on. Fish effectively drown because they lack oxygen necessary to breathe. Algae dramatically reduce water clarity and prevent sunlight from reaching vegetation on the riverbed. Without light, those plants die because they are unable to perform photosynthesis. In death, their detritus (dead remains) further contaminates the water, and the food source for shell fish, such as those delicious crabs, disappears. Add to this chain reaction the actual harmful chemicals that Reay’s study detected, such as mercury and various pesticides, and you become fully aware of how threatened this ecosystem has become. Additionally, this study only focuses on one of many estuaries within the Chesapeake Bay. There is a high probability that similar conditions would be found in others too.
Reay’s study does not suggest any solutions to this problem. It simply points out that there is a problem and that a solution must be found before it is too late. However, there is no easy fix. It cannot be illegal for farmers to fertilize their crops, for fertilization is necessary for production, though it’s runoff may be hurting surrounding ecosystems. It certainly is a dilemma. Reay does propose additional studies to be conducted, mostly in regard to how exactly runoff and the flow of nutrients into the river is affected by topography, landscape conditions, and weather. With greater understanding of these mechanisms that Reay has earmarked, perhaps a viable solution to the problem can be developed. But, in the mean time – while an answer is searched for - I don’t know about you, but I’m going to try and get my hands on as many of those crabs just in case (Reay).
No comments:
Post a Comment