The vertical structure of mesopelagic ecosystems is characterized by Vinogradov’s ladder, a trophic relay of vertical migrants spanning from the sunlit surface ocean to the sea floor. This vertical structure is imprinted further by seasonal migrants, light, temperature and nutrient profiles, particulate organic matter fluxes, global ocean circulation and oxygen minima zones (OMZ). Here we disentangle some to the key pathways (respiration, fecal pellets, deadfalls) by which passive and active fluxes impact the oceanic carbon sequestration of the biological carbon pump (BCP). Specifically we compare estimates to the ~1300 PgC of dissolved inorganic carbon (DIC) sequestered in the world’s oceans by the respiration of organic carbon. We draw on recent modelling results for metazoan migrants in the mesopelagic ocean as well as observation driven estimates for selected seasonally migrating copepods stocks and krill fecal pellet production in the Southern Ocean. Throughout we are mindful of the oxygen demand associated with DIC sequestration via the BCP, and point to a potential tipping process associated with expanding OMZ’s and interruptions to Vinogradov’s ladder.

Primary Presenter: Andre Visser, DTU Aqua (awv@aqua.dtu.dk)

Authors:

Andre Visser, Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark  (awv@aqua.dtu)

Jerome Pinti, College of Earth, Ocean, and Environment, University of Delaware, USA  (jpinti@udel.edu)

Sigrun Jonasdottir, National Institute of Aquatic Resources, Technical University of Denmark  (sjo@aqua.dtu.dk)

Emma Cavan, Imperial College London, Silwood Park, Berkshire, United Kingdom  (e.cavan@imperial.ac.uk)