The predictability of oxygen and its metabolic consequences for fisheries on decadal time scales

Earth system models (ESMs) project ocean conditions that are relevant to marine fisheries; over the next several decades, the ocean will warm, oxygen content will decline, and regions with low oxygen concentrations will expand. Critically, however, these trends are not spatially uniform and certain regions will experience more rapid change than others (Bopp et al. 2013). Temperature and oxygen availability jointly limit habitat viability, but are difficult to disentangle few predictive studies incorporate this information in developing projections of impacts on living marine resources (LMRs). 

A Ney physiologically mechanistic framework , the Metabolic Index (Φ, Deutsch et al. 2015) was recently developed that explicitly combines the joint influence of oxygen content in the ocean with the temperature dependent metabolic demands for a given organism. When Φ = 1, the resting metabolic demands of an organism are exactly matched by the available oxygen supply.It is possible to identify critical threshold, Φcrit, a physiological energetic barrier for a particular species which likely drives habitat. When Φ <Φcrit, the environment can no longer support the aerobic demands of species’ energetic requirements. Investigation of the synergistic effects of temperature and oxygen on driving physiological vulnerability of organisms within valuable fisheries is now possible with this index. 
Global ESMs have demonstrated sNill in predicting physical and biological variables important to fish and fisheries on seasonal to decadal time scales of significance to management (Tommasi et al. 2016, ParN et al. 2019). We propose to assess an existing forecast system’s ability to forecast metabolic indices in the global ocean on decadal timescales. Our objective is to examine the predictability of fisheries relevant environmental variables beyond sea surface temperature and chlorophyll, such as oxygen and related metabolic metrics, as well as potential limitations on fisheries that this metabolic index projects. 

Our hypothesis is that demands on metabolic rates due to rising temperatures and accompanied declines in dissolved O2, will restrict overall fishing potential by limiting biomass and that the metrics (Metabolic Index, potential catch) needed to forecast such restrictions are predictable on decadal timescales using an existing suite tools. The proposed program would analyze results from an existing suite of decadalYscale forecasts from the CESM Decadal Prediction Large Ensemble (CESMYDPLE; Yeager et al. 2018). Analyses will focus on establishing the predictability of environmental variables relevant to fish metabolic processes, including: temperature, plankton biomasses, oxygen, and Φ for representative taxa in each of the Large Marine Ecosystems of interest: Eastern Bering Sea, California Current, NE Atlantic Shelf, SE Atlantic Shelf, Gulf of Mexico, and Pacific Islands. 

The proposed worN meets the primary MAPP Program objectives of: 1) improving ESMs by adding the effects of oxygen concentrations on higher trophic levels; and 4) developing integrated assessment and prediction capabilities relevant to decision makers by analyzing the predictability of environmental variables and processes of consequence to fisheries and directly analyzing the predictability of higher trophic levels. This research will improve the modeling and understanding of climate related physical pathways that drive biogeochemical variability in U.S. LMEs. Proposed worN will address MAPP Priority Areas B. and C. 

Climate Risk Area: Marine Ecosystems