Kooperation, Konkurrenz und Kohlenstoff: Ein eigenschaftsbasierter Modellansatz zum mikrobiellen Einfluss auf die natürliche Speicherung von gelöstem organischen Kohlenstoff im Ozean.
Zusammenfassung der Projektergebnisse
Biogeochemical models are powerful tools to assess feedback mechanisms in the marine carbon cycle in a changing climate. While processes of carbon fixation, i.e. photosynthesis and fixing carbon into organic matter by microscopic algae (phytoplankton), are relatively well described in ocean models, processes of remineralisation, i.e. degradation of organic matter, are strongly underrepresented. This underrepresentation is of concern if we want to understand the mechanisms and time scales in which carbon is naturally sequestered in the ocean. DOC is a major organic carbon reservoir of ca. 700 Petagram in the ocean, comparable in size to the amount of atmospheric CO2, but the mechanisms that control its degradation are currently not well understood. The huge diversity of microoganisms and molecular compounds as well as their manifold interactions currently make a quantitative assessment of its remineralisation processes difficult. The project „Cooperation, Competition and Carbon: A trait-based modelling approach to microbial mediation of natural dissolved organic carbon storage in the ocean“ focused on microbial interactions and their impact on dissolved organic carbon (DOC) storage in the ocean. The main goal was to develop traitbased approaches to improve the representation of heterotrophic microorganisms in biogeochemical models, to assess their role in natural carbon sequestration in the ocean. Two main outcomes result from this project. First, a generic framework for the interactions in microbial communities was developed. The results have implications on several levels: On the species level, the delicate balance between cooperation and competition between microorganisms is governed by light- and nutrient acquisition traits. On the community level, network topology matters for the succession of microorganisms and organic compounds in a systematic way. With this microbial community model (MCOM), we provide the necessary generic framework to quantitatively assess such interactive networks. Secondly, nutrient limitation by bacteria was identified as a major driver of present-day concentrations of DOC in the surface ocean. Implementing the impact of macronutrients on the uptake rate of organic carbon by heterotrophic bacteria is helpful for further simulations of the marine microbial food web with the Darwin model, because it mechanistically underpins the remineralisation rate of DOC. In addition, implementing environmental controls on microbial growth and uptake rates allows an assessment of future changes related to these environmental controls, which have not been possible in previous models that focus only on net removal rates of DOC.
Projektbezogene Publikationen (Auswahl)
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Emergent Diversity and Persistent Turnover in Evolving Microbial Cross-Feeding Networks. Frontiers in Network Physiology, 2.
Lücken, Leonhard; Lennartz, Sinikka T.; Froehlich, Jule & Blasius, Bernd
