Key functional groups of planktonic protists contribute to particle export fluxes in the upwelling system off Peru

Sinking of biogenic particles drive the biological carbon pump, which transports photosynthetically fixed CO₂ from the ocean’s sunlit surface to the deep sea. In particular in productive ecosystems such as the Eastern Boundary Upwelling Systems vertical fluxes of biomass are high, sustaining extensive microbial respiration at depth and contributing to the formation of oxygen minimum zones. However, little is known on ecological drivers of particle export fluxes and the relative contribution of individual groups of planktonic protists. Here we show results from two campaigns to the Eastern Tropical South Pacific onboard the RV Meteor (April and June 2017), where we collected sinking particles at 6-8 depths in the range 40-600m using surface tethered drifting particle interceptor traps. We analyzed the taxonomic composition of the photoautotrophic community based on the pigment composition and the total protists community using amplicon sequencing of the 18S rRNA gene. We relate the community composition to environmental data and biogeochemical fluxes to identify drivers and controls of export fluxes. Our study provides new insights into the role of functional groups of planktonic protists as key actors in the biological carbon pump.

Presentation Preference: Oral

Primary Presenter: Susanne Neuer, Arizona State University (susanne.neuer@asu.edu)

Authors:

Kassandra Dudek, Arizona State University  (kldudek@asu.edu)

Helmke Hepach, GEOMAR Helmholtz Centre for Ocean Research Kiel  (hhepach@geomar.de)

Carolina Cisternas-Novoa, Memorial University  (acisternasno@mun.ca)

Frederic Le Moigne, Mediterranean Institute of Oceanography  (f.lemoigne@univ-brest.fr)

Anja Engel, GEOMAR Helmholtz Centre for Ocean Research Kiel  (aengel@geomar.de)