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Zooplankton in marine ecosystems and biogeochemical cycles: a critical but under-represented link in global models

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Monday, 17 September 2018, 12:00

Monday, September 17, 2018.  12:00 PM.  Zooplankton in marine ecosystems and biogeochemical cycles: a critical but under-represented link in global models. Jessica Luo, National Center for Atmospheric Research.  Sponsored by NOAA GFDL. More information here.

Marine ecosystems are increasingly stressed by anthropogenic activities that force broad-reaching changes to the biota and environment. Climate models project systematic declines in ocean oxygen, surface nutrients, primary productivity, and carbon export, which has direct impacts on atmospheric carbon feedbacks. However, models differ substantially in the spatial extent and mechanistic pathways that drive reductions in export flux, with marine zooplankton representing a large source of uncertainty in these processes. We developed a new size-structured and trait-based plankton ecosystem model for the Community Earth System Model (CESM), which reveals insights into the fundamental dynamics of energy transfer in the global oceans. Using the model to test basic ecological theories on biomass transfer, we show that there are two dominant marine trophic regimes. These regimes are driven by resource and grazing dynamics, and manifest in consumer-poor or consumer-rich ecosystems, which has strong implications for energy transfer to fisheries. Secondly, we use an offline modeling approach to evaluate the contribution of gelatinous zooplankton to global marine carbon cycle, a previously unconsidered flux. We estimate that fast-sinking particulate carbon mediated by gelatinous zooplankton could increase the carbon incident on the seafloor by up to three fold, which is globally significant and should be considered in future modeling efforts. Finally, I discuss perspectives and approaches for coastal biogeochemical modeling, including estuary models with biogeochemistry, the predictability of harmful algal blooms and other processes along the land-sea interface, regional ecosystem parameter optimization using machine learning, and submesoscale plankton behavioral modeling. 

Location  Smagorinsky Seminar Room, NOAA GFDL, Princeton, NJ