Dead Zones: Where even fish can’t live.
What are dead zones?
Dead zones are hypoxic areas of the world’s oceans. This means that they have less oxygen in the water than is needed to sustain sea-life. They tend to be located near to the shore, usually by heavily inhabited areas or by large river outlets.
How do they work?
Dead zones form when the ocean’s levels of nitrogen and phosphorous spike. These chemicals lead to a large influx of algae and other single-celled organisms. Although these algae produce oxygen during the day, they block the sunlight from reaching down into the ocean, restricting valuable resources to the aquatic life below. Once night comes around they stop their photosynthesis and go into cellular respiration which consumes the oxygen in the area. But it’s when the algae dies that most of the damage starts. After death the algae sinks to the bottom of the ocean and decomposes. Through the decomposition process the algae can deplete large amounts of oxygen in the water.
Recently evidence has been found that connects climate change to dead zones. As the top of the ocean gets warmer it mixes with the cooler, lower, levels of water. These cooler layers have less oxygen in them and when they mix the average amount of oxygen in the top layer of water decreases.
Short Flash film explaining hypoxia: http://www.gulfhypoxia.net/Overview/hypoxia_flash.asp
Why should we worry?
Since 1960 when scientists began studying the phenomenon the amount of dead zones globally has increased almost fortyfold. The most recent count of dead zones clocks in at around 405. These dead zones now take up about 95,000 square miles around the world. Most of these dead zones occur by the coast or by river outlets is because this is where the most of our pollution enters the ocean. Because of this pollution, specifically the fertilizer and fossil fuel runoff, nitrogen and phosphorous re dumped into the ocean. And so begins the birth of a hypoxic zone.
In a dead zone the fish that can flee are either forced to or die. But many slower, bottom dwelling animals don’t even have a chance to flee. Even if an area of ocean has enough oxygen to be livable studies have found that fish living in areas with lower oxygen levels tend to have smaller genitals in both males and females. This can lead to reproduction problems which slowly plague the area.
Dead zones lead to less fish which means that seafood ends up costing more. They lead to us eating seafood with various synthetic fertilizers in them which can in turn harm us. The fertilizers affect people living by the waterways and they can leach into people’s drinking water. Fish and sea creatures are massively wiped out. Even the fish that aren’t directly affected feel the effects of the dead zone. They have less to eat, and have to deal with lower levels of oxygen in the areas surrounding the dead zone.
Graph of ( #of dead zones/year): http://www.epa.gov/owow_keep/msbasin/pdf/diaz_data.pdf
What can we do?
We have a few options when it comes to solving the problem of dead zones. The most obvious is that we could cut back on fertilizers. Even when companies fight to keep using the fertilizers steps can be taken so that they don’t end up draining into our waterways. We can do this by adopt government incentives that require companies and/or cities to reduce their nitrogen runoffs.
Another solution would be to offer incentives for farmers to plant winter wheat instead of leaving their fields bare after the fall harvest. This would help prevent runoff from the fields.
Since fossil fuels do help the creation of dead zones we should continue to follow the steps that we are taking to cut back on our emissions. Special care should be given to making boats more efficient and to regulate boat cleaning at marinas where chemicals can run directly into the water.
Sources:
"150 'dead Zones' in World's Oceans."Msnbc.com. MSNBC, 29 Mar. 2004. Web. 14 Sept. 2010.
"Are the World's Oceans Endangered? Marine Biologists Say "Yes""The Daily Galaxy. 10 Mar. 2009. Web. 13 Sept. 2010. <http://www.dailygalaxy.com/my_weblog/2009/03/are-the-worlds.html>.
Diaz, Robert J., and Rutger Rosenberg. "Spreading Dead Zones and Consequences for Marine Ecosystems."Science Magazine15 Aug. 2008: 3-19.Sciencemag.org. AAAS. Web. 12 Sept. 2010.
"Mississippi River Basin Watershed Nutrient Task Force."US Environmental Protection Agency. 13 Jan. 2010. Web. 13 Sept. 2010. <http://www.epa.gov/owow_keep/msbasin/hypoxia101.htm>.
"Ocean 'dead Zones' Multiply from 4 to 400."Wildlife Extra - Online Wildlife Magazine for Wildlife Watchers and Lovers and Guide to UK Nature Reserves.Web. 13 Sept. 2010. <http://www.wildlifeextra.com/go/news/dead-zones823.html#cr>.
"Scientists Alarmed by Ocean Dead-zone Growth."SFGate. Ed. David Perlman. San Francisco Chronicle, 18 Aug. 2010. Web. 13 Sept. 2010. <http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/08/15/MNLD12ADSN.DTL>.
Smith, Roger.Crop Dusting. Digital image.Welcome to Flickr - Photo Sharing. Web. 13 Sept. 2010. <http://www.flickr.com/photos/rogersmith/871335892/>.
Images:
Deadzone. Digital image.Huffington Post. NASA. Web.
Diaz, Alejandro.Red Tide. Digital image.Wikipedia. Web. 13 Sept. 2010.
<http://upload.wikimedia.org/wikipedia/en/thumb/f/fa/Dead_Zone_-_Sediment.jpg/200px-
Dead_Zone_-_Sediment.jpg&keyword=×pan=>.
Smith, Roger.Crop Dusting. Digital image.Welcome to Flickr - Photo Sharing. Web. 13 Sept. 2010.
<http://www.flickr.com/photos/rogersmith/871335892/>.
St. Pe, Kerry. Dead Fish. Digital image.Science Daily. Web. 12 Sept. 2010.
<http://www.sciencedaily.com/releases/2007/11/071105094933.htm>.
Yasmin. Water Pollution. Digital image.Current. Web. 12 Sept. 2010.
<http://current.com/news/91923759_10-million-tons-of-chemical-fertilizer-discharged-into-
chinas-water-every-year.htm?xid=RSSfeed