About the project
The major bio-limiting nutrients in low to mid-latitude surface waters are nitrogen and phosphorous and their availability through time likely played a major role in evolution. In these areas of the ocean the majority of planktic foraminifera host endosymbionts, sharing their metabolic N and P with the autotrophic symbionts in exchange for organic carbon (C) in contrast to feeding on phytoplankton, other heterotrophs and particulate N (PN) when more nutrients are present. Thus, the origination and history of these symbioses may reflect changes in the ocean’s nutrient cycling.
Despite its importance, identifying photosymbiotic and trophic? activity in extinct species is challenging. However, recent instrumental and methodological developments we have been involved in have allowed the measurement of the nitrogen and carbon isotopes (δ15N, δ13C) on the organic matter that lies embedded within the mineral structure of ancient foraminifera (foraminifera-bound, FB), which are distinct between symbiotic-bearing and non-symbiotic foraminifera. Therefore, these promising new tools open a whole new archive to study symbiotic relationships and foraminifera ecology in the past.
Within this project the PhD candidate will carry out coupled analyses of foraminifera-bound nitrogen and carbon isotopes to answer the following questions:
- How did photosymbiotic activity and dietary sources within planktic foraminifera change over the past 60 million years?
- What can the symbiotic relationships tell us about nutrient availability in the surface ocean?
- How did photosymbiotic activity in foraminifera change as a response to global warming and ocean acidification in the past?
For full project details visit the Inspire project page.
- Professor Tom Ezard (University of Southampton)
- Alexandra Auderset (Princeton/University of Southampton)
- Kirsty Edgar (Birmingham University)