Dead zones occur when there is a deficiency of oxygen dissolved in the water, a phenomenon that can be caused in several different ways. Dead zones can occur naturally, but are more often formed when an algae population is fed by a large amount of nutrients in the water—often caused by fertilizer spills into bodies of water—and blooms into a massive population that depletes oxygen levels in the water. The population gets larger than what is sustainable, so a mass die-off begins and the algae sinks and begins to decompose, which further removes oxygen. Dead zones are major issues for aquatic plant and animal life, and can be deadly.
Nitrogen and phosphorous runoff from pesticides contaminates water in rivers and streams, running ultimately into the ocean. These nutrients foster the superfluous growth of algae in coastal waters. When the algae dies, it sinks to the bottom where bacteria break it down during bacterial respiration. This respiration process requires oxygen, depleting the water’s supply in vast quantities.
Recently the World Resources Institute launced a web site with lots of information on dead zones and their distrubution around the world. It is based on work I did that is now in Google Oceans. The Gulf Hypoxia Network has lots of good information too.
The correct WRI site is:
Click here to cancel reply.
Sorry,At this time user registration is disabled. We will open registration soon!
Don't have an account? Click Here to Signup
© Copyright GreenAnswers.com LLC