A Biogeochemical Model Intercomparison for the Eastern Bering Sea Shelf Journal of Geophysical Research: Oceans

Uncertainty related to biogeochemical model structure—the equations, parameters, and variables used to simulate lower trophic level dynamics—can contribute significantly to overall uncertainty of regional model predictions of living marine resources metrics such as primary production. This may be particularly true in shallow coastal regions, where there is growing interest in using these types of regional models to inform ecosystem management. Here, we use a biogeochemical model intercomparison to analyze the divergence of ecosystem metrics across models for the eastern Bering Sea shelf region, and identify the biogeochemical processes that may lead to this spread. We run three biogeochemical models with varying complexity coupled to the same regional ocean model and run 30‐year hindcast simulations spanning 1990–2020. We find that the models differ widely in their spatial and temporal patterns of simulated primary production, and that these differences propagate to most of the higher trophic level metrics examined. We highlight structural elements that lead to these differences, including (a) representation of benthic processes and their role in retaining nitrogen on the shelf, (b) the role of grazing control on spring bloom timing, and (c) the role of zooplankton groups in supporting regenerated production through the summer months. Overall, we conclude that the potential uncertainty associated with even well‐established biogeochemical models may be high, particularly when these models are pushed beyond the original contexts under which they were developed. End users should strive to acknowledge and communicate this, particularly when using biogeochemical model output in management contexts. Grant no. NA20OAR4310446