Two Items on Hypereutrophication
March 11, 2015This interview of the Chesapeake Bay Foundation’s director Alan Girard hits close to home because I live only 40 minutes from this important estuary. Much concern has been raised due to Governor Hogan’s easing of regulations addressing nutrient runoff into the Bay. However, what mainly caught my attention was how Girard singled out the use of manure fertilization as a very significant source of nutrient pollution into the bay. Traditionally, organic fertilizers (like manure) were regarded more “environmentally friendly” because they released their nutrients more slowly. This has important implications for the organic farming industry. Girard believes this problem could be managed by taking into account the slope of the hill where the fertilizer is to be applied. According to this other article, hypereutrophication is not the only adverse consequence of nutrient pollution. Excess nutrients also reduce the biodiversity of forest creeks because they speed up the decomposition of leaf litter that supports these ecosystems. Worse yet, the organisms that rely on a year round supply of forest debris play an important role in removing these excess nutrients from water column. This is comparable to the positive feedback loop taking place in the Chesapeake; whereby the hypereutrophication that diminishes the oyster population further exacerbates the problem due to their role in filtering phytoplankton. When I worked in the shrimp farming industry, we tried combining shrimp with oysters. We "seeded" oysters in both the reservoir and in the shrimp ponds. The oysters in the relatively clear water of the reservoir grew far better than those we placed in the hypereutrophic shrimp ponds. I know that hypereutrophication kills oysters due to anoxia, but we assiduously managed these ponds to prevent algae crashes, so I do not believe that anoxia played a role. If the oysters in the ponds were not “choking” on too much algae, their poor growth might also be attributed to the nutrient content of this algae population. Any thoughts on this from someone who is more qualified?
Posted by Antonio Chaves. Posted In : environmental news
