Harmful algal blooms, dead zones and fish deaths are the result of a process called eutrophication, which begins with the highest load of nutrients to estuaries and coastal waters.
Eutrophication is a great word that describes a big problem in the estuaries of the nation. Harmful algal blooms, dead zones and fish deaths are the result of a process called eutrophication, which begins with the highest load of nutrients to estuaries and coastal waters.
Sixty-five percent of the estuaries and coastal water bodies of the United States. They are degraded moderately to severely by the addition of excessive nutrients, which lead to algae blooms and low oxygen (hypoxic) waters that can kill fish and seaweed and reduce essential fish habitats. Many of these estuaries are also compatible with populations of bivalve molluscs (eg, oysters, clams, scallops), which naturally reduce nutrients through their filtration feeding activities.
The main culprits of eutrophication are the excess of nitrogen and phosphorus – from sources such as fertilizer runoff and septic system effluent to atmospheric rain from the burning of fossil fuels – that enter the bodies of water and fuel excessive growth of algae, which in turn reduces water quality and estuarine and coastal ecosystems.
Eutrophication can also produce carbon dioxide, which reduces the pH of seawater (ocean acidification). This slows the growth of fish and shellfish, can prevent the formation of shells in bivalve molluscs and reduces the capture of commercial and recreational fisheries, leading to smaller crops and more expensive fishery products.
In recent years, the NOAA National Coastal Ocean Science Centers (NCCOS), in collaboration with NOAA’s Northeast Fisheries Science Center, recruited indigenous residents of the estuaries, namely, bivalve molluscs to help decelerate and, in some cases, reverse the process of eutrophication, since they effectively remove the nutrients from the water, since they feed on phytoplankton and detritus.
An innovative modeling project on Long Island Sound showed that the oyster aquaculture industry in Connecticut provides between $ 8.5 and $ 23 million annually in nutrient reduction benefits. The project also showed that reasonable expansion of oyster aquaculture could provide as much nutrient reduction as the comparable $ 470 million investment in traditional nutrient reduction measures, such as improvements in wastewater treatment and better agricultural management practices .
NOAA scientists used aquaculture modeling tools to demonstrate that shellfish aquaculture compares favorably with existing nutrient management strategies in terms of nutrient removal efficiency and implementation cost. Documenting the water quality benefits provided by mollusc aquaculture has increased the acceptance of both communities and regulators of mollusc farming, not only in Connecticut, but throughout the country. In Chesapeake Bay, for example, nutrient removal policies include the collection of oyster tissue as an approved method, and in Mashpee Bay, Massachusetts, the cultivation and harvest of oysters and clams are part of the official nutrient management plan .