Researchers from Texas A&M University who have just returned from a visit to the Gulf of Mexico to explore the scope and size of this year’s dead zone have measured it to be currently around 8,500 square kilometres; approximately the same size as the states of Delaware and Rhode Island combined.
However researchers believe that 2011’s dead zone may continue to grow and become one of the largest ever, thanks in part to the record amounts of water being deposited into the Gulf from the Mississippi River.
Lead by Steve DiMarco, an oceanography professor at Texas A&M, the team of researchers traveled more than 2,300 kilometres throughout the Gulf of Mexico over a five day period. This was the first ever mission to focus on the dead zone’s size in June.
The dead zone off the coast of Louisiana has been continually monitored for about 25 years, and previous research has shown that nitrogen levels in the Gulf of Mexico intrinsically related to human activities have risen by 3 times over the past 50 years. Over the past 5 years, the dead zone in the Gulf of Mexico has averaged around 15,000 square kilometres, but is predicted to exceed 24,000 square kilometres this year, making it one of the largest ever recorded, according to the Louisiana Universities Marine Consortium.
“This was the first-ever research cruise conducted to specifically target the size of hypoxia in the month of June,” DiMarco says.“We found three distinct hypoxic areas. One was near the Barataria and Terrebonne region off the Louisiana coast, the second was south of Marsh Island (also Louisiana) and the third was off the Galveston coast. We found no hypoxia in the 10 stations we visited east of the Mississippi delta.”
“The largest areas of hypoxia are still around the Louisiana coast, where you would expect them because of the huge amounts of fresh water still coming down from the Mississippi River,” he adds.“The hypoxic area extends about 50 miles off the coast. The farther you go west toward Texas, there is still hypoxia, but less severe. However, we did see noticeable hypoxia near the Galveston area.”
DiMarco and colleagues will return to the area on August 8 to revisit many of the same locations for additional data.
Source: Texas A&M University