Congratulations!
Posted by Dr. Yoana Voynova, head of the department Coastal Productivity
We are happy to share that on 02.09.2024, PhD student Louise C.V. Rewrie successfully defended her PhD dissertation titled ‘Carbon Cycling in the Elbe Estuary’, at the University of Kiel with a ‘magna cum laude’. The defense took place at GEOMAR location.
Louise worked at the department „Coastal Productivity“, and her research has considerably advanced our knowledge on the functioning of estuarine ecosystems and inorganic and organic carbon cycling in estuaries under stress. Louise focused on anthropogenic stressors during the past 40 years such as heavy pollution in the past (1980s and earlier), and climate change more recently, with a focus on a several-year drought (2014-2020).
Louise found that it can take decades for an estuarine ecosystem to recover after heavy pollution from anthropogenic sources, and that the ecosystem functioning can change dramatically as a result, which ultimately alters the carbon cycling and carbon fluxes from land to sea. She highlighted a 7-year transitional ecosystem state between the polluted and recovery states, underlining the non-linear response of an estuary to anthropogenic stressors. While the estuary has largely recovered, since 1997, Louise also observed a continual increase in the inorganic carbon content (6-21 µmol/kg per year), which she linked to improved water quality and efficient carbon sequestration via primary production in the upstream river regions.
Caption: Significant shifts in carbon cycling and ecosystem states (1985–2020) in a temperate estuary (the Elbe) driven by pollution (1980s), water quality improvement (after 1990), and climate change (drought of 2014-2020). Figure was first published as Figure 1 in Rewrie et al. 2023a. Annual along-estuary dissolved inorganic carbon (DIC) patterns in the Elbe Estuary, with three distinct ecosystem states identified: Polluted, Transitional and Recovery states (Figure was first published in Rewrie et al. 2023a).
Louise found that estuaries already experience climate change, and several-year droughts (2014-2020) can decrease the inorganic carbon delivery from land to sea by on average 24%, despite an efficient organic carbon remineralization in the estuary. This has suggested that since we are already experiencing predicted climate change effects, this is ultimately altering the carbon fluxes in coastal and estuarine regions.
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