frontiers 
in Marine Science 
METHODS 
published: 28 September 2021 
doll: 10.23389/fmars.2021.723304 
Check for 
updates 
= = = 
Climate-Biogeochemistry 
Interactions in the Tropical Ocean: 
= 
= 
Data Collection and Legacy 
Gerd Krahmann'*, Damian L. Arevalo-Martinez', Andrew W. Dale’, Marcus Dengler'. 
Anja Engel’, Nicolaas Glock*?, Patricia Grasse*?, Johannes Hahn'+*, Helena Hauss’, 
Mark J. Hopwood’', Rainer Kiko'5, Alexandra N. Loginova*®, Carolin R. Löscher’, 
Marie Maßmig', Alexandra-Sophie Roy®, Renato Salvatteci*", Stefan Sommer’, 
Toste Tanhua' and Hela Mehrtens’ 
GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, * Institute for Geology, Department of Earth Science 
University of Hamburg, Hamburg, Germany, * German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 
‚eipzig, Germany, * Federal Maritime and Hydrographic Agency, Hamburg, Germany, ° Laboratoire d‘Oceanographie 
Je Villefranche-sur-Mer, Villefranche-sur-Mer, France, ° Institute of Oceanology Polish Academy of Sciences, Sopot, Poland 
Nordcee, Department of Biology and DIAS, University of Southern Denmark, Odense, Denmark, ° Genomic Microbiology. 
'nstitute of Microbiology, Kiel University, Kiel, Germany, ?° Institute of Geosciences, Kiel University, Kiel, Germany, !° Center 
‘or Ocean and Society, Kiel University, Kiel, Germany 
OPEN ACCESS 
Edited by: 
Maria LI. Calleja, 
Max Planck Institute for Chemistry, 
Germany 
Reviewed by: 
Craig Alexander Carlson, 
University of California, 
Santa Barbara, United States 
Dennis Arthur Hansell, 
University of Miami, United States 
*Correspondence: 
Gerd Krahmann 
gkrahmann@geomar.de 
From 2008 to 2019, a comprehensive research project, ‘SFB 754, Climate - 
Biogeochemistry Interactions in the Tropical Ocean,’ was funded by the German 
Research Foundation to investigate the climate-biogeochemistry interactions in the 
'ropical ocean with a particular emphasis on the processes determining the oxygen 
distribution. During three 4-year long funding phases, a consortium of more than 150 
scientists conducted or participated in 34 major research cruises and collected a wealth 
of physical, biological, chemical, and meteorological data. A common data policy agreed 
Jpon at the initiation of the project provided the basis for the open publication of all data. 
Here we provide an inventory of this unique data set and briefly summarize the various 
data acquisition and processing methods used. 
Keywords: biogeochemistry, oceanographyv, tropical ocean, oxygen, climate, oxygen minimum zone 
Specialty section: 
This article was submitted to 
Marine Biogeochemistry, 
a section of the journal 
5rontiers in Marine Science 
Received: 70 June 2027 
Accepted: 16 August 2021 
Published: 28 September 2021 
INTRODUCTION 
Citation: 
Krahmann G, 
Arevalo-Martinez DL, Dale AW, 
Dengler M, Engel! A, Glock N, 
Grasse P. Hahn J, Hauss H, 
Hopwood MJ, Kiko R, Loginova AN, 
Ööscher CR, Maßmig M, Roy A-S, 
Salvatteci R, Sommer S, Tanhua T 
and Mehrtens H (2021) 
Climate-Biogeochemistry Interactions 
in the Tropical Ocean: Data Collection 
and Legacy. 
Front. Mar. Sci. 8:723304. 
dal: 10.3389/fmars. 2021. 723304 
The distribution of oxygen in the ocean interior is controlled by an intimate interplay of physics 
and biogeochemistry. Circulation and mixing transport oxygen from the near-surface, where it is 
produced by photosynthesis and exchanged with the atmosphere, into the ocean interior. Oxygen 
consumption occurs throughout the ocean and is essentially driven by bacterial respiration of 
5rganic matter. Both the supply and consumption of oxygen are sensitive to climate change in 
ways that are not fully understood. A central objective of the Collaborative Research Center 
754 (Sonderforschungsbereich ‘SFB 754, Climate - Biogeochemistry Interactions in the Tropical 
Ocean’) was to better understand the observed changes in ocean oxygen distribution (see Figure 1) 
and thoroughly investigate the climate-biogeochemistry system in the tropical Atlantic and 
Pacific Oceans. The program was financed from 2008 through 2019 by the German Research 
Foundation (DFG). 
Addressing the SFB 754 goals required a highly multi-disciplinary approach. The SFB 754 
built upon the wide-ranging marine expertise available at the GEOMAR Helmholtz Centre 
-rontiers in Marine Science | www.frontiersin.orc 
September 2021 | Volume 8 | Article 72330«