Aquatic Ecosystems Essay

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Aquatic ecosystems Aquatic ecosystems are divided into freshwater and marine. There are about 18 major river basins, 211 lakes, and 22 marshlands in the Philippines. Most river systems in manila have been declared by the department of environment and natural resources as biologically dead. Human dominon over nature has finally reached the sea. With an ever-accelerating tide of human impact, the oceans have changed more in the last 30 years than in all of human history before. In most places, the seas have lost upwards of 75 percent of their megafauna-large animals such as whales, dolphins, sharks, rays, and turtles-as fishing and hunting spread in waves across the face of the planet. For some species numbers are down as much as 99 percent. Just to give you an idea by the end of the 20th century, almost nowhere shallower than 3,000 feet remained untouched by commercial fishing. Today places are now fished down to 10,000 feet. Most of the species we like to eat have plummeted since their historic highs. Red snapper, bluefish, and menhaden are all overfished in U.S. waters today, while grouper and capelin are far below their 19th-century numbers. Overfishing is only one small piece in a much larger puzzle of interacting impacts. We pump chemical and industrial pollutants into our rivers and oceans, heedless of consequences, and our unplanned experiment with greenhouse gases is gradually infiltrating the deep sea, changing ocean chemistry, impacting temperatures and oxygen levels, and shifting patterns of underwater currents with dramatic consequences. The path we are on today is pushing ocean ecosystems to the edge of their viability. Few people yet grasp the gravity of the predicament. The oceans have absorbed around 30 percent of the carbon dioxide released by human activity since preindustrial times, mainly from fossil-fuel burning, conversion of forests and

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