Kostadinov, T.S., Taniguchi, D., Carroll, D., Behrenfeld, M., Meiburg, E.H., and Wilhelmus, M.M. (2024)
Presented at:
Ocean Sciences Meeting 2024The particle size distribution (PSD) is a key property of marine ecosystems that links ocean optics and ocean ecology and biogeochemistry. Recently, Kostadinov et al. (2023) published a 2-component, coated spheres and backscattering-based ocean color algorithm for the retrieval of the PSD. The range of retrieved power-law PSD slopes globally is 2.5 to 6.0. The algorithm modeling spans mostly phytoplankton-sized particles and smaller. The retrieved PSD has been used to estimate absolute and fractional size-partitioned phytoplankton carbon (Kostadinov et al., 2023). Here, we explore the feasibility of extrapolating the power-law PSD retrieved from passive ocean color data with the Kostadinov et al. (2023) algorithm to the mesozooplankton size range, in order to estimate their abundance, carbon biomass, and diel vertical migration (DVM). Quantifying global DVM is important since it can transport carbon vertically, including via biogenic hydrodynamic transport (BHT). We use the climatological PSD based on OC-CCI v5.0 ocean color data as a test case, and demonstrate the feasibility of this approach in achieving realistic global retrievals, with some modifications to the PSD parameters (tuning, rescaling). Results are compared and tuned against two data sets independent from the ocean color PSD: the Behrenfeld et al. (2019) lidar-based DVM retrieval, and the MAREDAT (Moriarty and O'Brien, 2013) in-situ zooplankton biomass data set. We present our global abundance, biomass and DVM retrievals and discuss the results and the need for tuning/rescaling in the context of theoretical and observational considerations that indicate that a power law PSD with a very conserved slope applies to marine ecosystems (e.g. Sheldon et al., 1972; Behrenfeld et al., 2021; Hatton et al., 2021). We focus on the implications of a slightly modified version of the competition-neutral ecosystem model of Behrenfeld et al. (2021), an emergent property of which is that phytoplankton power-law PSD slope in stable oligotrophic conditions is 4.1. This effort is part of a NASA-funded project also involving laboratory experiments designed to assess BHT, as well as the parameterization of DVM in the ECCO-Darwin ocean biogeochemistry model.
