Top Story: March 11, 2010

Dead Zones Threaten Baltic Sea

Baltic Algal Bloom
The vast Baltic Sea is home to countless wrecks including four-hundred year old viking ships, WW II spy planes and more. These wrecks have remained pristinely preserved because brackish Baltic waters effectively create a dead zone where ship-eating worms have been unable to live.

Now, because of chemicals commonly found in agricultural fertilizer and sewage, life in the Baltic Sea is faced with a new type of dead zone. A dead zone without marine life and covered in algae.

The Baltic Sea has been experiencing algal blooms, a rapid growth of phytoplankton due to an influx of nutrients. These blooms occur naturally, but on a much smaller scale. Similar to plants, algae flourish when levels of nitrogen and phosphorous are present in high amounts.  When it rains, the nitrogen in fertilizer from upstream farmland runs off into the Baltic Sea. Phosphorous by-products from sewage systems discharge also end up in it's vast waters.

The massive explosion of algae threatens the whole marine ecosystem. As the algae blooms it starves seaweed of light. Because seaweed is essential reproduction habitat for pike and perch, their reproduction is is almost non-existent in areas where they once thrived. But these fish aren't the only one's to suffer. When the algae die, they land on the seabed, and feed the bacteria which consume the water's oxygen. Without oxygen, cod, herring and other animals can't live. Consequently, the Baltic Sea is now home to seven of the world's ten largest marine "dead zones".

Although the nine countries that surround the Baltic have legally agreed to clean up the Baltic sea by 2021 through a series of laws, they remain largely unenforced. As a result, the sustainability of this popular vacation resort and fishing ground remains threatened.

comments

  • Marlenezahran

    This is a major problem….Didn't countires around the Baltic Sea such as Germany and Poland  at least try to lower fertilizer use or  decrease the amount of sewage system discharge into the sea. It almost seems like they don't care!!

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