In magazine Nature Geoscience, Roxane Maranger and Nina Caraco, wrote that the collapse of the fisheries from decades of over fishing has played a significant role in disturbing the balance between nitrogen entering and leaving costal water systems. The joint Canada-US study examines the world’s 58 coastal region which shows that unbalanced ecosystems have wide-ranging consequences.
According to Maranger and Caraco commercial fishing has played a vital role in removing man-made nitrogen from coastal waters. Maranger, a biology professor at the Université de Montréal (Canada), explained that fish accumulate nitrogen as biomass, and when humans move fish from the ocean to the table through commercial fisheries, they are returning part of this terrestrial nitrogen generated by humans back to the land.
Caraco, an aquatic biogeochemist at the Cary Institute of Ecosystem Studies (Millbrook, New York, U.S.) wrote: “While nitrogen is essential to plant and animal life in oceans, human export of nitrogen from land to ocean has resulted in exploding nitrogen levels in coastal waters over the past century. Nitrogen-rich fertilizer makes its way into coastal waters via a network of streams and rivers. And thus fertilizer run-off is a significant source of nitrogen pollution to many coastal regions around the world.”
Maranger informed that commercial fishing has removed 60 percent of the nitrogen form the coastal region in past four decades. Now this figure has come down to 20 percent. Maranger said that increased nitrogen levels in coastal ocean ecosystems throughout the world have resulted in excessive plant growth, lack of oxygen, severe reductions in water quality and in fish and other animal populations. Therefore it is good to have commercial fishing in coastal region to decrease the level of nitrogen from the ocean.
