Babette Hoogakker

UKRI Future Leaders Fellow 'Fate of ocean oxygenation in a warming world'

My research interests are in the application and interpretation of foraminiferal isotope and trace metals and flow vigour proxies, to study the interaction between the biogeochemical cycles, large-scale ocean circulation and climate change in the past. My current projects focus on the development and application of proxy methods to reconstruct oxygen concentrations of seawater in the geological past. Since the 1960s the oceans have lost ~2% of their oxygen, a trend expected to accelerate in relation with global warming. Future deoxygenation, along with overfishing, threatens the sustainability of economically important fisheries and marine ecosystems and will impact global biogeochemical cycles. However, predictions of the future are hampered by a poor understanding of the longer-term natural oxygen cycle. Application of proxy methods to reconstruct oxygen concentrations in the past gives us an opportunity to extend our knowledge of the longer term oxygen cycle, and help improve predictions of future oxygen level changes.

The material we use to develop proxy methods and past time-series involves the shells of microorganisms called foraminifera. Some species float near the ocean surface, called planktonic foraminifera, and can be used to assess the presence of subsurface oxygen minimum zones, seawater temperatures, etc. Species that live on or in sediments at the bottom of the ocean are termed benthic foraminifera and can be used to reconstruct bottom water oxygen concentrations and ventilation. I have been extracting foraminifera from sediments from the International Ocean Discovery Program to determine if there have been changes in the natural extent and intensity of the Atlantic Ocean, the shallow Pacific Ocean OMZ oxygen minimum (or 'dead') zones (e.g. areas where oxygen levels are too low to support aerobic life) over the last glacial-interglacial cycle (e.g. last ca. 130,000 years).

As part of future research we will look at utilizing organic carbon in foraminifera to understand past ocean productivity, carbon cycling and climate change.