A size- and trait-based model of the copepod community in the global ocean

Surface-dwelling copepods greatly mediate the efficiency of carbon export and sequestration in the deep ocean. Although it has been shown that traits distribution within the community (such as size), together with life history and behavior (e.g. ontogeny, vertical migration and feeding strategy), define the magnitude and efficiency of carbon export out of the photic zone, the implementation of such in an unified framework still remains elusive within global ecosystem models. In this paper, we present a mechanistic plankton-ecosystem model (unicellular protists and copepods) that generates an emergent copepod community, its trait-distribution, and the resulting carbon export within a global ocean circulation model. The model considers several sizes of protists and copepods, and explicitly characterizes ontogeny, seasonal vertical migrations and feeding strategies. We compare the performance of the model with data and identify the main mechanisms driving differences in carbon export. This simple, yet more realistic model, opens the possibility to improve end-to-end size-structured models of marine systems and investigate associated biogeochemical processes.