Reducing Hypoxia in the Northern Gulf of Mexico: Lessons from Simple and Complex Models

Gulf hypoxia has received considerable scientific and policy attention because of its large size (up to 22,000 square km), potential ecological and economic effects, and the need to understand the implications of various nutrient management strategies in the large Mississippi River watershed. Over the past 20 years, a number of different models have been developed to simulate the severity and areal extent of hypoxia in the northern Gulf of Mexico, and to predict the consequences of management actions. The models range from simple statistical models to complex three-dimensional fully coupled hydrodynamic-biogeochemical models. The size and the complexity of these models have been steadily increasing due to developments in computer technology and computational techniques, and also in response to new scientific paradigms that have emerged over time forcing modelers to broaden the scope of their original models. We presentan overview of hypoxia models developed for the Gulf of Mexico hypoxic zone and discuss the lessons learned, and some fundamental differences between simple and complex models in evaluating the effectiveness of nutrient management strategies for reducing hypoxia.