This project will provide critical information and predictive tools to coastal managers for understanding how species will respond to changing hypoxia conditions from ongoing and projected warming in the Gulf of Mexico. Coastal managers and stakeholders will then be able to plan for nutrient reduction strategies to minimize the hypoxic zone within the context of climate change and species health.

Why We Care
The northern Gulf of Mexico continental shelf hosts one of the largest coastal hypoxic zones, also called “dead zones,” in the world and continues to have widespread negative impacts on the marine ecosystem and species. The formation, evolution, and ecological impact of the hypoxic zone under current conditions are relatively well studied. However, the hypoxic zone under future conditions with the combined effect of climate warming, ocean deoxygenation, and nutrient inputs remains to be explored. Resource managers and stakeholders need knowledge and a framework suitable for the future northern Gulf of Mexico to plan nutrient reduction strategies aimed to minimize the hypoxic zone and evaluate the effects of the hypoxic zone on living resources within the context of a changing climate.

Atlantic Croaker, a key fishery resource in the Gulf of Mexico, will be one of species studied by the project. Credit: Robert Aguilar, Smithsonian Environmental Research Center.

What We Are Doing
A dissolved oxygen concentration of less than 2 mg/L is usually used to define environmental hypoxia, but the impact of hypoxic stress on marine animals (i.e., physiological hypoxia) is controlled by both dissolved oxygen concentration and animal metabolic rate modulated by temperature. To better understand the impact of hypoxia on marine organisms of importance, this project will characterize the northern Gulf of Mexico hypoxic zone under climate warming and eutrophication, develop and calibrate an ecophysiological framework for commercially and ecologically important species in the northern Gulf of Mexico, and apply it to study temperature-dependent habitat shifts and contraction and body size shrink for those species in northern Gulf of Mexico over the next three decades.

This project aims to answer four questions:

• • How will the hypoxic zone evolve over the next three decades with climate warming and coastal eutrophication under different emission scenarios?
  • What are the temperature-dependent thresholds of physiological tolerance for dissolved oxygen among selected ecologically and economically important species?
  • Can the observed trends in species distributions be explained using historical hydrographic information from observations and hindcast ocean models, interpreted through trait-based mechanistic models?
  • Which species are most vulnerable to habitat shift and contraction and body-size shrink, and how will their habitat shift across latitude, depth, and seasons over the coming decades?

The goal of the project is to provide a better scientific basis for policymakers and resource managers to develop policies on hypoxic zone management, habitat and fish stock assessment, and more general policies that account for the anticipated regional impacts of global climate change.

This project is part of the Coastal Hypoxia Research Program and is led by Dr. Junhong Liang in collaboration with Dr. Cassandra Glaspie and Dr. Nancy Rabalais. Institutions involved with the study include Louisiana State University, Princeton University, University of Louisiana Lafayette and the U.S. Geological Survey. A Management Transition Advisory Group will be used to engage resource managers and policymakers throughout the project to ensure the transition of research products to management.