Dead Zones! © The GlobalEd 2 Project Photo credit: Jeff Schmaltz, NASA. Available at: http://news.nationalgeographic.com/news/2010/02/100305-baltic-sea-algae-dead-zones-water/ Photo credit: Jeff Schmaltz, NASA The Baltic Sea, the world’s largest dead zone © The GlobalEd 2 Project

Essential Questions: What are “dead zones”? How do “dead zones” occur? How do “dead zones” affect living organisms? © The GlobalEd 2 Project

Enduring Understandings: “Dead zones” are large areas of water with little oxygen “Dead zones” occur when excess fertilizer and untreated sewage seep into the water. “Dead zones” cause fish and other bottom-dwelling animals to move outside the area to avoid being suffocated. Much underwater life also dies. © The GlobalEd 2 Project

Facts About “Dead Zones” With each passing decade, the number of “dead zones” worldwide has doubled Nearly every summer, the bottom waters of Lake Erie's central and western basins lose so much oxygen that fish can't survive. © The GlobalEd 2 Project

Facts About “Dead Zones” (continued) Aquatic creatures need oxygen in the water to live.  However, sometimes, conditions exist in which the dissolved oxygen in the water is used up by organisms faster than it can be replaced from the air. If all the oxygen gets used up, the organisms will suffocate Around the world low oxygen waters are a growing problem, killing fish and changing local ecosystems. © The GlobalEd 2 Project

Major Cause of “Dead Zones”: The major causes of “dead zones” are man-make, resulting from the build up of excess fertilizers and untreated sewage, which seeps into the water. © The GlobalEd 2 Project

How Can “Dead Zones” be Reduced? Reduce/eliminate the amount of fertilizers used Properly treated sewage © The GlobalEd 2 Project