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% (μ ± 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 km2 and restore hypoxic waters to normoxic conditions.