Reducing Hypoxia in the Gulf of Mexico: Advice from Three Models

Summer hypoxia in the bottom waters of the northern Gulf of Mexico has received considerable scientific and policy attention because of potential ecological and economic impacts from this very large zone of low oxygen and because of the implications for management within the massive Mississippi River watershed. An assessment of its causes and consequences concluded that the almost 3-fold increase in nitrogen load to the Gulf is the primary external driver stimulating the increase in hypoxia since the middle of the last century. Results from three very different models are compared to reach the consensus that large-scale hypoxia likely did not start in the Gulf of Mexico until the mid-1970s and that the 30% nitrogen load reduction called for in an Action Plan to reduce hypoxia, agreed to by a federal, state, and tribal task force, may not be sufficient to reach the plan’s goal. Caution is also raised for setting resource management goals without considering the long-term consequences of climate variability and change.