One of the consequences of global warming is a trend towards decreasing dissolved oxygen contents in the world’s oceans. In coastal settings in particular, this trend is further amplified by human-induced eutrophication. The phenomenon of so called deoxygenation has been registered increasingly – and model predictions suggest a worsening of the conditions in the near future, with direct implications for economically, societally and environmentally critical ecosystems.
Periods of oxygen-poor conditions in the marine realm are also known from past environments, and can be traced in the sedimentary record and geochemical signal of calcitic organisms preserved in it, making it possible to learn more about the relationship between deoxygenation and climate change, and their impact on ecosystems. Ultimately, this will allow to gain insight into potential outcomes of today’s climate and environmental changes, but to do so it is necessary to develop proxies for the reconstruction of past conditions.
The aim of my PhD project is the improvement of benthic foraminifera as a proxy for palaeo-bottom-water oxygenation, with a focus on the trace elemental (Mn/Ca) and isotopic (δ13C) signal of their shells. To establish a reliable proxy, it is necessary to understand the exact relation between the environmental parameter, the geochemistry of the surrounding seawater, as well as the incorporation mechanisms during biomineralisation of the organism.
The Gullmar-, Koljö- and Havsten Fjord, located at the Swedish west coast, North Atlantic, and the Santa Barbara Basin off California, Eastern North Pacific, lend themselves as ideal study regions, as they present prime examples of coastal settings characterized by periods of low-oxygen conditions.
In addition to field work, I will also carry out experimental laboratory studies, and methods will be a combination of several state-of-the-art microanalytical tools, including synchrotron-and plasma-based analyses.