Gulf of Mexico Hypoxia

Dr. De Mutsert has an interest in the ecological impacts of the hypoxic zone in the northern Gulf of Mexico on fish and fisheries.  Her past research has investigated the impacts of low oxygen conditions on fish and fisheries using ecosystem model simulations.  For future work she plans to build on these existing simulation models by coupling spatially-explicit water quality, bioenergetics and ecosystem models to evaluate alternative management strategies, inter-annual differences in water flows, nutrient loading and water temperatures, and longer-term climate changes on living resources.

Dr. de Mutsert has received funding from NOAA’s Center for Sponsored Coastal Ocean Research to continue this work under the NGOMEX 2016 funding cycle.

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2014 forecast of summer hypoxic zone size.  Image source: Dr. Nancy Rabalais

Current Research

NGOMEX 2016: User-driven tools to predict and assess effects of reduced nutrients and hypoxia on living resources in the Gulf of Mexico

Expansive hypoxia in the Northern Gulf of Mexico (NGOMEX) will continue to affect ecologically and economically important living resources, but the magnitude, predictability and even the direction of these changes remain elusive. Managers and stakeholders need readily available and quantitative tools to predict and evaluate the effects on living resources of planned nutrient reduction strategies aimed to minimize the hypoxic zone. We plan to develop user-friendly, management-scale relevant forecasting tools and quantitative indicators. We will also assess the minimum data needs (monitoring or modeling parameters, and time and space scales) to ensure these forecasts produce accurate and useful data required by managers and stakeholders. Previous work in the region by the P.I.s and colleagues resulted in three tested models and expansive datasets from seven cruises, which will be used to estimate effects of reduced nutrient inputs and hypoxic volume on living resources in the NGOMEX, and will form the basis of user-friendly tools to be transferred to resource managers. The coupling of two different fisheries modeling approaches (physiological-based and ecosystem-based) with the same 3D hydrodynamic/water quality model ensures that questions of varying levels of resolution can be addressed. Both coupled “physics to fish” approaches will assess the trade-offs of nutrient loading, namely the combined effects of increased productivity through bottom-up fueling, and altered habitat capacity or quality due to hypoxia. Interactive effects of other anthropogenic stressors such as fishing and climate change will be evaluated, as will the degree of model detail required. Outputs include species-specific fish growth rate potential as a measure of Essential Fish Habitat (EFH), and biomass and catch of ecologically and economically important living resources. Simplified indicators of ecosystem change will be developed. A high degree of interaction with both managers and stakeholders will be an integral part of the program. Frequent meetings with a team of advisors complemented with annual workshops will ensure the utility of the work for management purposes, and the transfer of tools to resource managers and stakeholders. The primary target audience is NOAA-NMFS coupled with the NOAA Center for Sponsored Coastal Ocean Research, Regional Sea Grant Extension and their fisheries stakeholders, the Northern Gulf Institute, the interagency Mississippi River/Gulf of Mexico Hypoxia Task Force, the NOAA RESTORE Act Science Program, and key state agencies. An initial workshop will define both manager needs and stakeholder expectations and answer the question of the requisite predictions and frequency of product delivery needed. The second workshop will include training and testing of the developed management tools, whereas the last workshop will focus on technology transfer and applications. This approach, and the use of adaptive science where feedback during workshops will be incorporated into work priorities, ensures transition of research to management throughout the scope of this project. The outcomes of this project will be an improved capability to assess the effects of alternative management strategies on ecosystem function, living resources, and fisheries revenue.

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Conceptual diagram of the constituent model interactions and their anticipated end products. A more detailed schematic of these linkages, as well as their calibration and validation, can be viewed here (new window).

RESTORE: Ecosystem Modeling to Improve Fisheries Management in the Gulf of Mexico

The population of a recreationally or commercially important fish species can be influenced by several factors such as the abundance of its prey, the abundance of its predators, mortality events, and ocean conditions which can determine if early life stages make it to suitable nursery habitat. Understanding how these factors interact is not easy, but advances in computer modeling in the Gulf of Mexico is making it possible to develop computer-based ecosystem models that take many of these factors into account.This project will further refine Gulf of Mexico ecosystem models working in concert with fisheries managers to make sure the model outputs are relevant to the decisions managers face. This project will integrate managers into the model refinement process through workshops and regular communication. Working with input from managers, the model development team will adapt existing models to address current challenges associated with managing gag grouper and Gulf menhaden and incorporate the outputs from the updated models into the stock assessment process for each species. In addition, the model development team will construct new features to test model accuracy and better represent spatial processes and stressors such as habitat preferences, red tides, and fish migration patterns. The model development team will align model development and outputs to coincide with the requirements and timing of the stock assessment and management process.