As the population has increased, land areas have developed with housing, schools, shopping malls, power plants, dumps, dams, roadways, cars, and waste treatment centers. The impact of this growth and development has a far reach effect on multiple ecosystems. This development has greatly affected the ecosystems of the Long Island Sound watershed.
A variety of pollutants enter the water system through both point sources, specific locations and non-point sources, broader sites. Rain water washes over farms, parking lots, city builds, salt piles, roadways, out dated dilapidated electric power plants, dumps(a plethora of surfaces) picking up and carrying with it a multitude of substances as the water travels to the Long Island Sound. These pollutants include salts, nitrogen, oil, detergents, plastics, pesticides, and chemicals, pharmaceutical, and micro fibers.
Salt naturally occurs in estuaries and oceans, but when the salt levels in the waterways exceed normal levels, problems follow within the ecosystem. The delicate balance of the ecosystem can be tipped with road salts flooding water systems.
The salt in the estuaries and oceans come from the rocks. When it rains, the water droplets pick up carbon dioxide as the water droplets fall to the land. The carbon dioxide makes the rain slightly acidic which wears down the rocks which releases salt into the water.
Unfortunately, there is a lot of salt placed on roadways during the winter to make driving safer. This salt is highly mobile and easily enters into streams and rivers. Freshwater organisms in these systems are not used to such high levels of salt and are adversely impacted.
Maine’s fishermen are trying to address the over fishing of eels with a lottery system. Overfishing is having a huge impact on the eel population. As elvers return to the shores of Maine from the Sargasso, they are being harvested and sold for over $2000.00 a pound to Asia. They are then exported and farmed in Asia where they are sold for an even higher price.
Additionally, overfishing of the sand eel and krill is having a significant impact on migratory patterns and health of Atlantic salmon. As a result, Atlantic salmon is returning to their native rivers thinner and earlier. Concerns are arising about the kind of impact the early return will have on the spawning patterns because the salmon will need to survive in the rivers until January when they spawn.
Dams and Loss of Habitat
Another problem facing migratory fish is the blockage to watershed spawning grounds. Land development has created obstacles such as the construction of dams and habitat loss with landfills which blocks access to the spawning grounds of migratory fish. Hydroelectric dams have posed a catastrophic effect to the eel population. When adult eel journey back to the Sargasso, a hydroelectric dam kills and injures the eel when they are caught in the turbines.
Unable to reach spawning grounds, the populations of American Shad, Atlantic salmon, and American eel are being severely impacted.
Oxygen & Nitrogen
A healthy stream and river has balanced levels of oxygen and nitrogen levels. Marine creatures need appropriate levels of oxygen, carbon, nitrogen, and phosphorus in the ecosystem to survive. The marine creatures in these ecosystems depend on healthy levels of dissolved oxygen to breath. Hypoxia can become problematic in the summer because water stratifies and bottom waters can effectively be separated from oxygen replenishment from the atmosphere.
Another situation that can cause hypoxia to occur is when there are excess rain storms and run off into the watershed. The runoff carries extra nutrients into the water to the phytoplankton. These microscopic marine plants grow and reproduce vigorously under these conditions. There quick growth also has a short life cycle. The tiny marine plants, phytoplankton, die quickly. When the phytoplankton die, and are decomposing, the process uses the dissolved oxygen in the water. This depletes the levels of oxygen for other marine creatures that depend on the oxygen in the water. A low oxygen level, or hypoxia, stresses fish and other marine creatures. Fortunately, fin fish are able to swim away from the affected areas, but benthic creatures such as clams, mussels, and oysters are not.
In conclusion, there is an interconnected relationship between oxygen and nitrogen levels in marine environments. Levels of nitrogen often have a direct relation to the amount of dissolved oxygen available. Excess nitrogen can cause algae blooms. After the large numbers of algae multiply and grow, or “bloom” they die off quickly. The decomposition of the dead algae is what depletes oxygen levels. When the algae, or phytoplankton dies, its decomposition by bacteria, animals, uses up the dissolved oxygen in the water. These algae blooms deplete oxygen levels in the water because algae uses oxygen as it decomposes resulting in lower levels of dissolved oxygen in the water
which in turn causes hypoxia, or low levels of dissolved oxygen. Hypoxia stresses marine creatures in such environments.