Preprints
https://doi.org/10.5194/bg-2022-188
https://doi.org/10.5194/bg-2022-188
 
25 Oct 2022
25 Oct 2022
Status: this preprint is currently under review for the journal BG.

Extracellular enzyme production in the coastal upwelling system off Peru during different upwelling scenarios: a mesocosm experiment

Kristian Spilling1,2, Jonna Piiparinen1, Eric P. Achterberg3, Javier Arístegui4, Lennart T. Bach5, Maria T. Camarena-Gómez1, Elisabeth von der Esch6, Martin A. Fischer7, Markel Gómez-Letona4, Nauzet Hernández-Hernández4, Judith Meyer3, Ruth A. Schmitz7, and Ulf Riebesell3 Kristian Spilling et al.
  • 1Marine Research Centre, Finnish Environment Institute, Helsinki, Finland
  • 2Centre for Coastal Research, University of Agder, Kristiansand Norway
  • 3GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 4Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
  • 5Institute for Marine and Antarctic Studies, University of Tasmania, Tasmania, Australia
  • 6Institute of Hydrochemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Munich, Germany
  • 7Institute for General Microbiology, Christian Albrechts University Kiel, Germany

Abstract. The Peruvian upwelling system is a highly productive ecosystem that could be altered by ongoing global changes. We carried out a mesocosm experiment off Peru, with the addition of water masses from the regional oxygen minimum zone (OMZ) collected at two different sites simulating two different upwelling scenarios. Here we focus on pelagic remineralization of organic matter by extracellular enzyme production of leucine aminopeptidase (LAP) and alkaline phosphatase activity (APA). After addition of the OMZ water, dissolved inorganic nitrogen (N) was depleted, but the standing stock of phytoplankton was relatively high even after nutrient depletion (mostly >4 µg chlorophyll a L-1). During the initial phase of the experiment, APA was 0.6 nmol L-1 h-1 even though the PO43- concentration was >0.5 µmol L-1. Initially, the dissolved organic phosphorus (DOP) decreased, coinciding with an increase in PO43- concentration probably linked to the APA. The LAP activity was very high with most of the measurements in the range 200–800 nmol L-1 h-1. This enzyme degrades amino acids and these high values are probably linked to the highly productive, but N-limited coastal ecosystem. Also, the experiment took place during a rare coastal El Niño event with higher-than-normal surface temperatures, which could have affected the enzyme production. Using a non-parametric multidimensional scaling analysis (NMDS) with a generalized additive model (GAM), we found that biogeochemical variables (e.g. nutrient and chlorophyll a concentrations), phytoplankton and bacterial communities explained up to 64 % of the variability in APA. The bacterial community explained best the variability (34 %) in LAP. The high hydrolysis rates for this enzyme suggests that pelagic N remineralization supported the high standing stock of primary producers in the mesocosms after N depletion.

Kristian Spilling et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-188', Anonymous Referee #1, 14 Nov 2022
  • RC2: 'Comment on bg-2022-188', Anonymous Referee #2, 04 Dec 2022

Kristian Spilling et al.

Kristian Spilling et al.

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Short summary
We carried out an enclosure experiment with surface water off Peru with different additions of deep water representing possible future ocean scenarios. In this paper we report on enzyme activity, and provide data on the decomposition of organic matter. We found very high activity of an enzyme breaking down protein, suggesting this is important for the nutrient recycling both at present and in the future ocean.
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