Predicting summer hypoxia in the northern Gulf of Mexico: Redux

We report on the evolution and accuracy of a model used to predict the mid-summer area of hypoxia (oxygen <= 2 mg l(-1)) in the northern Gulf of Mexico, use it to test for impacts from the Deepwater Horizon oil spill (2010), and estimate the N loading that would meet a management goal. The prediction since 2000 were 100% +/- 6% (mu +/- 1 SE) of the actual value. The predicted in 2010 was 99% of that actual value, suggesting that the net effect of the 2010 oil spill on the hypoxic zone size was negligible. A tropical storm, however, may have reduced the potential size of the hypoxic zone. Lowering the May nitrogen load to about 70,000 mton N nitrate + nitrite would bring the model's predicted hypoxic zone size down to the management goal of 5000 km(2) and restore hypoxic waters to normoxic conditions. (C) 2011 Elsevier Ltd. All rights reserved.