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Changes in Our Planet's Aquatic Biodiversity

Our planet's surface is mostly covered in water, so it should be no surprise that the balance of this water system greatly impacts Earth's climate. Yet, everything we do on land tends to drain into this water system and have a powerful influence on the Earth's aquatic biodiversity.

The Impact of Irrigation on Aquatic Biodiversity
It should be no surprise that irrigation is a major threat to the current aquatic biodiversity. Yet, irrigation issues have been historically dealt with as an engineering feat, rather than an environmental impact. Little thought was given to how such construction projects and resulting water flows would impact aquatic biodiversity. But the changes made to the composition of feeding and receiving bodies of water has had a drastic impact on the support provided for aquatic life, and thus on the biodiversity of such water bodies.

The Impact of Water Contamination on Aquatic Biodiversity
Many unscrupulous people have been using lakes and oceans as waste disposal areas over the years. Much of the animal and plant life in these areas dies. Species that are particularly sensitive to the dumped products have even been pushed to extinction. In one region alone and article in Scientific American by Micklin and Aladin points out that the number of fish species decreased by 81%, bird species decreased by 50%, and mammal species decreased by 54%.

The Impact of Excessive Evaporation on Aquatic Biodiversity
When the evaporation rate goes beyond annual rainfall and snow melt, the fresh water supply is threatened. This in turn threatens biodiversity in a water body. The body of water may soon become a marsh, or even a desert.

The Aral Sea is an example quoted by Miclin and Aladin to show how this can take place. The Aral Sea split into two bodies of water that became known as the Small Aral Sea and the Large Aral Sea. When the Large Aral Sea was split up again, it had three more distinct parts. As you can imagine, this made drastic changes in the plant and animal life. The 100,000 hectares of marshland that was there in 1960 even decreased to 15,000 hectares in 1990.

Water depletion is not the only issue that can be caused by excessive evaporation. The results of fresh water evaporating away from a large body of water can be an increase in the salinity of that body of water. Two of the above mentioned split-offs of the Aral Sea became so saline that they are no longer habitable for most water species and no longer suitable as water supplies. Even the Large Aral Sea salinity has gone from 14 grams per liter to over 100 grams per liter. Contrast this with an average ocean salinity of 53 grams per liter and you'll understand just how serious excessive evaporation can be. Even the once lush surrounding plant life has been mostly unable to survive these changes.

The Global Aquatic Biodiversity Problem
The problem we have around the world is that all of these factors are working together at once in various areas of the world. It takes expansive efforts for us to reverse these changes, even in the early stages. California's Salton Sea and Africa's Lake Chad have both entered this sort of transition. Even places with great wealth struggle to find the money to fight the problem, so it will take extraordinary assistance for poorer regions to fight it. But, the long-term impact to our world of these changes in aquatic biodiversity could be disastrous.


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