TF写作真题第024套（mm014）

MM_014

Recent research has shed light on the health of aquatic ecosystems and the results are not good. to combat the declining health of marine ecosystems many scientists and politicians are advocating marine conservation techniques to ensure the preservation and restoration of ecosystems in oceans, seas, rivers and bays. marine conservation focuses on limiting human-caused damage to marine ecosystems as well as focusing on preserving vulnerable marine species. in the case of chesapeake bay, several techniques have been recommended to support sustainable populations of diverse and valuable animal species.

The first recommended technique is to discontinue the harvesting of crabs. unsustainable fishing practices have reduced crab populations to dangerous levels, so much so that the chesapeake bay crabs are now endangered. halting crab fishing and harvesting will ensure that the crab population can return to healthy size. stopping exploitive fishing is the surest way to restore health to an aquatic ecosystem.

A second aquatic ecosystem restoration technique is to introduce oysters into the bay environment. oysters are able to filter and mitigate pollutants and act as natural aquatic filters. like fish, oysters pass water over their gills exchanging gas. however, oysters also filter out particles in the water. in essence the oyster is absorbing all the pollution in its surrounding area and pumps out fresh, clean water.

Another manmade threat to aquatic ecosystems comes from water pollution from farms that use fertilizers. fertilizer is not a problem if used carefully. however, if too much fertilizer is used or applied at the wrong time, it can easily wash off and flow into lakes and streams. fertilizers contain nutrients such as nitrates and phosphates that can over-stimulate the growth of aquatic plants and algae, creating an imbalance in the delicate ecosystem. educating farmers of the consequences of fertilizer usage as well as instructing them on proper usage and application should be forefront in conservation techniques.

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综合写作MM 014音频

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