Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans
Carolin R. Löscher1,a,Hermann W. Bange1,Ruth A. Schmitz2,Cameron M. Callbeck3,Anja Engel1,Helena Hauss1,Torsten Kanzow1,b,Rainer Kiko1,Gaute Lavik3,Alexandra Loginova1,Frank Melzner1,Judith Meyer1,Sven C. Neulinger2,c,Markus Pahlow1,Ulf Riebesell1,Harald Schunck2,Sören Thomsen1,and Hannes Wagner1Carolin R. Löscher et al.Carolin R. Löscher1,a,Hermann W. Bange1,Ruth A. Schmitz2,Cameron M. Callbeck3,Anja Engel1,Helena Hauss1,Torsten Kanzow1,b,Rainer Kiko1,Gaute Lavik3,Alexandra Loginova1,Frank Melzner1,Judith Meyer1,Sven C. Neulinger2,c,Markus Pahlow1,Ulf Riebesell1,Harald Schunck2,Sören Thomsen1,and Hannes Wagner1
Received: 22 Jan 2015 – Discussion started: 17 Mar 2015 – Revised: 04 May 2016 – Accepted: 24 May 2016 – Published: 20 Jun 2016
Abstract. Recent modeling results suggest that oceanic oxygen levels will decrease significantly over the next decades to centuries in response to climate change and altered ocean circulation. Hence, the future ocean may experience major shifts in nutrient cycling triggered by the expansion and intensification of tropical oxygen minimum zones (OMZs), which are connected to the most productive upwelling systems in the ocean. There are numerous feedbacks among oxygen concentrations, nutrient cycling and biological productivity; however, existing knowledge is insufficient to understand physical, chemical and biological interactions in order to adequately assess past and potential future changes.
In the following, we summarize one decade of research performed in the framework of the Collaborative Research Center 754 (SFB754) focusing on climate–biogeochemistry interactions in tropical OMZs. We investigated the influence of low environmental oxygen conditions on biogeochemical cycles, organic matter formation and remineralization, greenhouse gas production and the ecology in OMZ regions of the eastern tropical South Pacific compared to the weaker OMZ of the eastern tropical North Atlantic. Based on our findings, a coupling of primary production and organic matter export via the nitrogen cycle is proposed, which may, however, be impacted by several additional factors, e.g., micronutrients, particles acting as microniches, vertical and horizontal transport of organic material and the role of zooplankton and viruses therein.
The ocean loses oxygen due to climate change. Addressing this issue in tropical ocean regions (off Peru and Mauritania), we aimed to understand the effects of oxygen depletion on various aspects of marine biogeochemistry, including primary production and export production, the nitrogen cycle, greenhouse gas production, organic matter fluxes and remineralization, and the role of zooplankton and viruses.
The ocean loses oxygen due to climate change. Addressing this issue in tropical ocean regions...