Patterns of mesozooplankton community composition and vertical fluxes in the global ocean

Abstract

Vertical variations in physical and chemical conditions drive changes in marine zooplankton community diversity and composition. In turn, zooplankton communities play a critical role in regulating the transfer of organic matter produced in the surface ocean to deeper layers. Yet, the links between zooplankton community composition and the strength of vertical fluxes of particles remain elusive, especially on a global scale. Here, we provide a comprehensive analysis of variations in zooplankton community composition and vertical particle flux in the upper kilometer of the global ocean. Zooplankton samples were collected across five depth layers and vertical particle fluxes were assessed using continuous profiles of the Underwater Vision Profiler (UVP5) at 57 stations covering seven ocean basins. Zooplankton samples were analysed using a Zooscan and individual organisms were classified into 19 groups for the quantitative analyses. Zooplankton abundance, biomass and vertical particle flux decreased from the surface to 1000m depth at all latitudes. The zooplankton abundance decrease rate was stronger at sites characterised by oxygen minima (< 5 micromol O2./kg) where most zooplankton groups showed a marked decline in abundance, except the jellyfishes, molluscs, annelids, large protists and a few copepod families. The attenuation rate of vertical particle fluxes was weaker at such oxygen-depleted sites. Canonical redundancy analyses showed that the epipelagic zooplankton community composition depended on the community structure of surface phytoplankton and the quantity and the quality of the produced particulate organic matter. We provide a consistent baseline of plankton community structure together with estimates of vertical flux and a contribution to our understanding of global zooplankton dynamics in the upper kilometer of the global ocean. Our results further suggest that future changes in surface phytoplankton composition and mesopelagic oxygen loss might lead to profound changes in zooplankton abundance and community structure in both the euphotic and mesopelagic ocean. These changes may affect the vertical export and hereby the strength of the biological carbon pump

Dark plumes of glacial meltwater affect vertical distribution of zooplankton in the Arctic

“…A better understanding and parametrization of these processes is necessary for the development of predictive models of biogeochemical cycles in the ocean. Still, little is known about the potential implications of global climate change on zooplankton vertical distribution, which in turn shapes the export and subsequent strength of the biological carbon pump 65 , 66 . Previous investigations have shown that during the Arctic summer, the majority of zooplankton biomass concentrates close to the surface 24 , 67 , 68 .…”

Seasonal changes in taxonomic, size composition, and Normalised Biomass Size Spectra (NBSS) of mesozooplankton communities in the Funka Bay, southwestern Hokkaido: Insights from ZooScan analysis

“…Theoretically, a slope of −1 for the NBSS indicates a steady zooplankton community, a slope steeper than −1 indicates a low transfer efficiency, and a flat slope indicates a high transfer efficiency (Sprules & Munawar 1986). It should also be noted that a flat slope is attributable to a high abundance of large zooplankters (García-Comas et al 2014, Soviadan et al 2022. The NBSS intercept becomes large when either the overall biomass or the number of small organisms increases (Moore & Suthers 2006).…”

Self-organisation of zooplankton communities produces similar food chain lengths throughout the ocean

“…1a). This classical view 16 underpins conceptual theory and modelling 17,18 , yet has not been tested globally.…”