Dissolved+Oxygen

__What is dissolved oxygen?__
Dissolved oxygen is the oxygen saturated into the water that is vital to fish and other aquatic life to breathe. It indicates the degree of health of the water and its ability to support a balanced aquatic ecosystem Dissolved Oxygen can also be represented as mg/L.[1]  Dissolved oxygen enters the water by incorporating into the water from the outside air.[2]

__Why is dissolved oxygen important to aquatic life?__
Dissolved oxygen is only one percent oxygen. Gas levels cannot exceed 110 percent because it is harmful to aquatic life. If oxygen levels fall below 1-2 mg/L even for only a couple of hours it will result in mass fish deaths. If dissolved oxygen gets that low then the fish suffocate. Fish in waters that have too much dissolved gases however may suffer from "Gas Bubble Disease". But, this is a very rare thing that happens. The bubbles or emboli block the flow of blood through blood vessels causing fish to die. =__What can affect dissolved oxygen levels? __ = If the water temperature is to warm, there possibly wouldn’t be enough Dissolved Oxygen in the water. When there are too many organisms, plants, aquatic life in the area, they could over populate the area causing the Dissolved Oxygen to be all used up.[4] In fast moving bodies of water, rushing water is aired out by rocks and brush by bubbles as it churns over rocks and tumbles over several thousand tiny rapids. If these streams are unpolluted they are usually full of dissolved oxygen and aquatic life. On the other hand, in slow running bodies of water it is harder for a lot of oxygen to enter the water. Also a Dam placed in a body of water can cause the running water to slow down and cause there to be no aeration in the water which makes it hard for oxygen to enter.[5] (picture above) [6] = =

=__What happens when there is not enough dissolved oxygen?__ = = =  When there is not enough dissolved oxygen in the water then the aquatic life cannot live. Fish use that Dissolved oxygen to breathe through there gills. The warmer the water is the less dissolved oxygen that is in the water which makes it really hard for aquatic life to survive.   __Where does dissolved oxygen come from? __  <span style="font-family: Arial, Helvetica, sans-serif;">There are 3 big sources of dissolved oxygen, radiant energy from the atmosphere, waves whipping around and strong winds, or phototsythesis by aquatic plants. The amount of dissolved oxygen rises and falls on a daily basis. The amount of dissolved oxygen increases diring the day and decreases during the night. Dissolved oxygen increases during the day because thats when plants are able to draw energy from the sun. At night the amount of dissolved oxygen decreases because they do not have an energy source. [7]

,Sources: [1] dissolved oxygen (DO). 2003. INFOhio Science Online. http://www.fofweb.com/Science/default.asp?ItemID=WE40 [2] Why Dissolved Oxygen is Important. 1998-2008. Lenntech. http://www.lenntech.com/why_the_oxygen_dissolved_is_important.htm. Joe Howard January 6, 2009 [3] Common Causes of Fish Kills in Florida. Fish and Wildlife Research Institute. http://www.floridamarine.org/features/view_article.asp?id=19955 [4] Dissolved Oxygen. Kentucky.gov. January 8, 2008. http://www.state.ky.us/nrepc/water/wcpdo.htm [5] Dissolved Oxygen (DO). Monday April 23, 2007. http://bcn.boulder.co.us/basin/data/COBWQ/info/DO.html [6] Marylands dam safety program. 2002-2008. http://www.mde.state.md.us/Programs/WaterPrograms/Dam_Safety/index.asp [7] Dean, Larry. Dissolved oxygen. January 7 2008 http://edis.ifas.ufl.edu/FA002