Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes

• DOI: 10.3389/fmars.2022.880550
• Publication Date: 2022-06-20T06:37:34Z
• Authors: Joaquin Ortiz; Javier Arístegui; Nauzet Hernández-...; Mar Fernández-Méndez; Ulf Riebesell
• Keywords: New production

Artificial upwelling has been proposed as a means of enhancing oceanic CO 2 sequestration and/or raising fishery yields through an increase in primary production unproductive parts the ocean. However, evidence its efficacy, applicability and side effects is scarce. Here we present part results 37-day mesocosm study conducted oligotrophic waters off coast Gran Canaria. The goal was to assess situ artificial on pelagic community. Upwelling simulated via two modes: i) singular deep-water pulse ii) recurring supply every 4 days; each mode at four different intensities defined by total amount nitrate added: approx. 1.5, 3, 5.7, 11 µmol L -1 . In this focus phytoplankton response size-fractionated 14 C rates (PP), Chlorophyll biomass. We observed increases PP, accumulated biomass that scaled linearly with intensity. primarily benefitted larger size fractions, causing shift from pico- nano- microphytoplankton. Recurring addition produced more under higher than single addition. It also reached significantly PP per unit added nutrients showed stronger reduction percentage extracellular release increasing These demonstrate communities can effectively adjust regardless intensity, but differently depending mode. upwelled generated efficiencies build-up same volume nutrient load.