According to the latest prediction from NOAA, 2012 Gulf of Mexico hypoxic zone could range from a low of approximately 1,197 square miles to as much as 6,213 square miles. The wide range is the result of using two different forecast models. The forecast is based on Mississippi River nutrient inputs compiled annually by the U.S. Geological Survey (USGS).
The smaller dead zone forecast was generated by researchers from the University of Michigan. Their model is based on spring nutrient inputs from the Mississippi River which are significantly lower than average due to drought conditions throughout much of the watershed.
The larger dead zone forecast is from Louisiana Universities Marine Consortium and Louisiana State University scientists. The Louisiana forecast model includes prior year’s nutrient inputs which can remain in bottom sediments and be recycled the following year. Floods in 2011 and low flows in 2012 influenced the “carryover effect” for the 2012 prediction.
Hypoxic zones, also known as "dead zones" are said to be caused by nutrient pollution and other factors that deplete oxygen in seawater. Fish and other marine life are sometimes unable to survive at or near the seafloor where hypoxic zones exist.
source: NOAA
Showing posts with label dead zones. Show all posts
Showing posts with label dead zones. Show all posts
Wednesday, July 18, 2012
Friday, July 8, 2011
Gulf of Mexico Dead Zone Predicted for 2011
The Gulf of Mexico’s hypoxic zone is predicted to be the largest ever recorded due to extreme flooding of the Mississippi River this spring, according to an annual forecast by a team of NOAA-supported scientists from the Louisiana Universities Marine Consortium, Louisiana State University and the University of Michigan. The forecast is based on Mississippi River nutrient inputs compiled annually by the U.S. Geological Survey (USGS).
Scientists are predicting the area could measure between 8,500 and 9,421 square miles, or an area roughly the size of New Hampshire. If it does reach those levels it will be the largest since mapping of the Gulf “dead zone” began in 1985. The largest hypoxic zone measured to date occurred in 2002 and encompassed more than 8,400 square miles.
Hypoxia is caused by excessive nutrient pollution, often from human activities such as agriculture that results in too little oxygen to support most marine life in bottom and near-bottom water. The hypoxic zone off the coast of Louisiana and Texas forms each summer and threatens valuable commercial and recreational Gulf fisheries. In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed more than $1 billion to the Gulf economy taking 22 million fishing trips.
During May 2011 stream-flow rates in the Mississippi and Atchafalaya Rivers were nearly twice that of normal conditions. This significantly increased the amount of nitrogen transported by the rivers into the Gulf. According to USGS estimates, 164,000 metric tons of nitrogen (in the form of nitrite plus nitrate) were transported by the Mississippi and Atchafalaya Rivers to the northern Gulf. The amount of nitrogen transported to the Gulf in May 2011 was 35 percent higher than average May nitrogen loads estimated in the last 32 years.
The actual size of the 2011 hypoxic zone will be released following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium between July 25 and August 6. Collecting these data is an annual requirement of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force Action Plan.
source: NOAA
Scientists are predicting the area could measure between 8,500 and 9,421 square miles, or an area roughly the size of New Hampshire. If it does reach those levels it will be the largest since mapping of the Gulf “dead zone” began in 1985. The largest hypoxic zone measured to date occurred in 2002 and encompassed more than 8,400 square miles.
Hypoxia is caused by excessive nutrient pollution, often from human activities such as agriculture that results in too little oxygen to support most marine life in bottom and near-bottom water. The hypoxic zone off the coast of Louisiana and Texas forms each summer and threatens valuable commercial and recreational Gulf fisheries. In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed more than $1 billion to the Gulf economy taking 22 million fishing trips.
During May 2011 stream-flow rates in the Mississippi and Atchafalaya Rivers were nearly twice that of normal conditions. This significantly increased the amount of nitrogen transported by the rivers into the Gulf. According to USGS estimates, 164,000 metric tons of nitrogen (in the form of nitrite plus nitrate) were transported by the Mississippi and Atchafalaya Rivers to the northern Gulf. The amount of nitrogen transported to the Gulf in May 2011 was 35 percent higher than average May nitrogen loads estimated in the last 32 years.
The actual size of the 2011 hypoxic zone will be released following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium between July 25 and August 6. Collecting these data is an annual requirement of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force Action Plan.
source: NOAA
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