Friday, April 27, 2012

Solutions

One main obvious solution is to discontinue the use of synthetic fertilizers because they are the leading cause of hypoxia, due to their source of nitrogen and phosphorus. Discontinuing the usage of these fertilizers is hard and unlikely for farmers because they are very dependent on them. One helpful and small solution for this is to lower the use of the fertilizers and only use as much as the soil can observe.
Another very effective way is to use natural sources of nutrients, for example manure. Also using farming methods such as no-till and contour cropping. These solutions reduce runoff because they allow soil to absorb more water and nutrients.
Another solution is to restore coastal wetlands. This provides a natural filter and helps remove excess nutrients from the water before it reaches the ocean. We can all help out with preventing ocean dead zones, weather by refusing the use of fertilizers or even just a small portion of cleaning up trash and liter to help keep the ocean clean.

Friday, April 13, 2012

http://www.youtube.com/watch?v=CUTcE403FJs

Dead Zones Continue to Rise

The number of dead zones from the 1960's to 2008 has doubled and continues to grow.  From 1997-2007 the Virginia Institute of Marine Science has recorded that dead zones have increased form four to four hundred.  The newest dead zones are being found in the southern hemisphere- South America, Africa, parts of Asia says Robert J. Diaz of the Virginia institute of Marine Science.  Diaz says some of the increase is due to just discovering low oxygen levels that have existed for years are just being found, also new ones have developed.  Scientist mainly blame fertilizers and other farm run off.  Diaz say that as fertilizers become more expensive farmers will begin seriously looking at ways to retain them on the land.  In the late 80s and early 90s, the Black Sea was the largest dead zone in the world, however between 191-2001, the process was reversed due partly because of the Soviet Unions fall and high prices of fertilizers.  Sewage discharge also contribute to the problem because they help the algae blooms to flourish.  Climate change could be adding to the problem as well.  The lack of oxygen can also force fish into warmer waters closer to the surface, perhaps making them more susceptible to disease.  Many regions are expected to experience more sever periods of heavy rain, which could wash more nutrients from farmland into rivers.  A portion of Big Glory Bay in New Zeland became hypoxic after salmon farming cages were set up, but began recovering when the cages were removed.  A dead zone has been newly reported off the mouth of Yangtze River in China, this area has been hypoxic sense about the 1950's.  Ove Hoegh-Guldber, a professor at the ARC Centre of Excellence for Coral Reef Studies(CoECRS) and the University of Queensland in Australia, says there is growing evidence that declining oxygen levels in the ocean have played a major role in at least four of the planets five mass extinctions.  It is found that it can cause fish to have smaller ovaries, produce fewer eggs, so larvae are smaller and less likely to survive.    According to a study form the Leibniz Institute of Marine Sciences in Germany, marine dead zones will increase by 50% by 2050.

Monday, April 2, 2012

http://m.youtube.com/watch?v=ahOmeTOIrRg

Gulf of Mexico Dead Zone

This dead zone occurs in the gulf at the mouth of the Mississippi river. During the past 5 years, the dead zone has averaged about 5,800 square miles and has predicted to exceed 9,400 square miles this year, which would make it one of the largest ever recorded. (according to the Louisiana Universities Marine Consortium). The reason why it is such a large hypoxia area is because 41% of the United States drains into the Mississippi river, than into the gulf. There are mostly farms that boarder the Mississippi, which dump their waste such as pesticides and fertilizers, into the rivers. There are also many cities that dump things such as their sewage into the river as well. These discharges have a high level of nitrogen and phosphorus which causes large phytoplankton to bloom. Previous researchers have shown that nitrogen levels in the Gulf related to human activity have tripled over the past 50 years.

Wednesday, March 21, 2012

Causes and Effects

Dead zones are caused by an increase in chemical nutrients in the water, known as eutrophication. Eutrophication can lead to an increase in the density of certain types of phytoplankton, known as an algae bloom. These algae blooms die off and as they do, oxygen is used up and due to the oxygen being used up it causes hypoxia conditions.
Dead zones are caused naturally but also by human activities. Fertilizers is the major human related cause. The natural causes are coastal upwelling, changes in the wind and water circulation patterns, runoff from sewage, and urban land use.
Due to low oxygen levels, there have been problems with the reproduction of fish, low egg counts, and lack of spawning. It's been found in the study of the Gulf killifish by the Southeastern Louisiana University that the never of eggs in females living in hypoxia waters were only 1/7 the number of eggs in fish living in normal oxygen level waters.

Monday, February 13, 2012

What are ocean dead zones?

It's where areas of the sea floor are hypoxic, meaning they have very low or completely zero, concentrations of dissolved oxygen. These dead zones are caused by an increase in chemical nutrients in the water. These chemical nutrients are produced by excess nitrogen from farm fertilizers, emissions from vehicles and factories, and from the sewage. These chemical nutrients spur the growth of thick algae, and underneath this algae the oxygen slowly vanishes and causes fish, crabs and other marine animals to suffocate and die. This is becoming a big problem today because it's spreading over the sea floors rapidly and is covering nearly the entire east and south coasts of the U.S as well as several west coast river outlets. Today 405 dead zones are known worldwide, compared to only 49 in the 1960's.