Fish community structure and bentho-pelagic coupling by fish from shelf to open ocean environments

Size-based fish community models have been developed to characterize the structure of fish communities (biomass distribution) and to describe energy flows between fish. Thus far, these models have overlooked important aspects of fish diversity that emerge due to variation in feeding strategies (pelagic, benthic or bentho-pelagic) and behaviors (diel vertical migrations) that are all associated with the vertical structure of a fish community. Here, we present a size- and trait-based fish community model that resolves the vertical structure of a fish community and bentho-pelagic coupling by fish from shelf systems to open ocean environments. Fish individuals interact with each other through predator-prey interactions that are determined by a combination of habitat overlap in the water column and body sizes of predator and prey. Our results show how variation in pelagic-benthic resources, in combination with seabed depth, change the dominant fish functional groups and the vertical structure of the community. We further show that fish feeding interactions export carbon to depth at continental slopes when benthic resources are high (typical for temperate and polar environments). Carbon export occurs less in areas where fish communities are primarily organized by pelagic resources. The results highlight the driving forces of fish community structure in marine ecosystems. The model is used to predict variation in fish community structure and energy flow across marine ecosystems on a global scale.