What is Dead zone (ecology)?
'''Dead zones''' are [[hypoxic]] (low-[[oxygen]]) areas in the world's [[ocean]]s and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 ml of O<sub>2</sub>/liter. Once DO falls below 0.5 ml O<sub>2</sub>/liter in a body of water, everything dies. With such low concentration of DO, the water does not support the aquatic life living there. [[File:Aquatic Dead Zones.jpg|thumb|center|400px|Aquatic dead zones 2010]] In March 2004 the newly established [[UN Environment Programme]] published its first [[UN Environment Programme|Global Environment Outlook Year Book]] (''GEO Year Book 2003''). It said there were 146 dead zones in the world's oceans. In these zones [[marine life]] could not live due to low oxygen levels. Some of these zones were as small as a square kilometer (0.4&nbsp;mi<sup>2</sup>), but the largest dead zone covered 70,000 square kilometers (27,000&nbsp;mi<sup>2</sup>). A 2008 study counted 405 dead zones worldwide.<ref>NOAA: Gulf of Mexico 'dead zone' predictions feature uncertainty. ''National Oceanic and Atmospheric Administration'' (NOAA). June 21, 2012.</ref> == References == {{reflist}} [[Category:Ecoregions]] [[Category:Oceans]]