Including filter-feeding gelatinous macrozooplankton in a global marine biogeochemical model: model–data comparison and impact on the ocean carbon cycle

Abstract. Filter-feeding gelatinous macrozooplankton (FFGM), namely salps, pyrosomes and doliolids, are increasingly recognized as an essential component of the marine ecosystem. Unlike crustacean zooplankton (e.g., copepods) that feed on prey order magnitude smaller, filter feeding allows FFGM to have access a wider range organisms, with predator-over-prey size ratios high 105:1. In addition, most produce carcasses and/or fecal pellets sink 10 times faster than those copepods. This implies rapid efficient export organic matter depth. Even if these organisms represent < 5 % overall planktonic biomass, their associated flux could be substantial. Here we present first estimate influence particulate deep ocean based biogeochemical model NEMO-PISCES (Nucleus for European Modelling Ocean, Pelagic Interaction Scheme Carbon Ecosystem Studies). this new version PISCES, two processes characterize FFGM: preference small due sinking pellets. To evaluate our simulated distribution, compiled abundance observations into monthly biomass climatology using taxon-specific biomass–abundance conversion. Model–observation comparison supports model's ability quantify global large-scale patterns distribution but reveals urgent need better understand factors triggering boom-and-bust dynamics before can reproduce observed spatio-temporal variability FFGM. substantially contribute carbon at depth (0.4 Pg C yr−1 1000 m), particularly in low-productivity regions (up 40 where they dominate by factor 2. The FFGM-induced increases importance depth, transfer efficiency close 1.