Blue Carbon refers to carbon captured and sequestered in marine and coastal environments, typically consisting of organic carbon stored in marine and estuarine sediments as well as that sequestered in cold water corals and salt marshes (Smeaton et al 2020, Shafiee 2021). The freshwater Blue Carbon component, with carbon stored in fluvial and lacustrine sediments, is less well defined. Freshwater marl lakes which actively accumulate calcium carbonate rich sediment are a potentially important contribution to freshwater Blue Carbon as in these settings carbon is both sequestered and stored
Marl lakes in their natural state are highly alkaline, carbonate rich lakes, with a diversity of macrophytes recognised in the European Union Habitats and Species Directive (Wiik et al 2015a). The accumulation of calcium carbonate as marl in these lake systems is through a combination of direct precipitation, driven by seasonal variations in a range of physicochemical parameters, and biochemical processes as the calcite forms as incrustations on macrophytes, notably Characeae and Potamogetonaceae (Duston, 1986). The marcophytic diversity of a healthy marl lake can lead to very rapid accumulation of marl sediment particularly during the summer months.
Wiik et al (2015b) use a range of palaeoecological and geochemical approaches to define the aquatic ecosystem changes in the recent past but faced a challenge in defining the nature and timing of human impact on the marl lake ecosystems, with many modern lake systems a product of environmental changes first initiated in prehistory. In this project, palaeoecological and geochemical analysis of the marl sediments accumulated during the Late Glacial and early Holocene will offer an insight into how these marl lake ecosystems adapted to rapid and extreme changes in the lacustrine and terrestrial environment. This project will involve field work on Orkney and islands off western Scotland to sample sediments from marl lakes that are active and inactive both in the past and the present. This project will develop techniques and methodological approaches to overcome traditionally perceived challenges, bringing these disciplines together and gain a perspective that will connect past and future ecosystem dynamics.
This long view of the response to changes in both biochemical and physiochemical parameters will define the health and resilience to environmental change of present day marl lake systems. In terms of nature based solutions, marl lakes are similar to saltmarshes in that with better understanding of how these ecosystems contribute to carbon sequestration and storage then we are better placed to actively conserve and restore them.
The application deadline is January 7th at 17:00. By this deadline applicants must have filled in the IAPETUS online application from following instructions here: https://www.iapetus2.ac.uk/how-to-apply/. The application form requires you to write several sections of text about your interest in this PhD and your suitability for PhD research. Serious applicants are strongly advised to make contact with Dr Eileen Tisdall by email well before the deadline to discuss their application. After making the application, candidates will be shortlisted for the next stage of the IAPETUS DTP selection process.