24.04.2023: Ocean Circulation and Climate Dynamics Colloquium

When?  Monday, April 24, 2023 at 11 am
Where?    Konferenzraum 8A/1.101, Wischhofstr. 1-3

Abstract:
Benthic foraminifera are ubiquitous marine protists. Various species of foraminifera have specific adaptations to environmental conditions in their ecological niche. For example, several species from O2 depleted environments are able to denitrify and thus an important sink for oceanic reactive nitrogen and some species even show a metabolic preference of NO3- over O2 as an electron acceptor.
Consequently, we can apply our knowledge about these adaptations to the paleo-record. I will present examples of O2 and NO3- reconstructions using the porosity of denitrifying and O2 respiring foraminifera. For example, paleo oxygen reconstructions from the Peruvian oxygen minimum zone (OMZ) indicate that the OMZ was similar in extend but weaker during the Last Glacial Maximum (LGM), compared with the Late Holocene. In addition, initial paleo NO3- records from intermediate water depths around the Pacific indicate generally elevated NO3- concentrations during the LGM, compared to the Holocene and a synchronous decrease in NO3- during Heinrich Stadial 1.
Finally, I will present an outlook about two novel findings regarding benthic foraminifera: First, I will give a brief introduction about the widespread occurrence of intracellular phosphate storage in benthic foraminifera, which is likely another adaptation to O2 depletion. Then, I will present a case study about the influence of hydrothermal activity at the Mid Atlantic Ridge on benthic foraminiferal assemblages. Assemblages close to hydrothermal vents have a specifically different composition than assemblages in further distance and might be valuable paleo indicators for past hydrothermal activity.

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