In this study we show the potential of using FB-δ15N to detect photosymbiosis in modern and fossil foraminifera. Due to distinct isotopic signatures related to ammonium recycling, FB-d15N can distinguish between foraminifera with dinoflagellate-symbionts, non-dinoflagellate symbionts and non-symbiotic foraminifera. However, we also point out that in regions with strong oceanographic gradients the application of FB-d15N could be complicated. Next we will apply FB-d15N to extinct foraminifera as far back as the Cretaceous. So stay tuned!
So far, there are studies on fossil-bound δ15N in corals, diatoms, otholiths, and teeth (shark, mammal, dinosaur, hominin). In future studies we aim to apply this method to further organisms and geological archives. Together with collaborator Jeffrey Thompson we currently work on modern and Carboniferous sea urchins/echinoids.
Everyone knows about coral bleaching, but what about foraminifera bleaching? In this project, we will investigate how the photosymbiotic relationship between the major marine calcifiers, planktic foraminifera and their symbionts changed in response to past global warming and ocean acidification over the past 60 million years (e.g. MMCO, MECO, PETM).