Dr Clare Bird

Project Title: Understanding ecological dependencies in planktonic foraminifera: A role for the microbiome under climate change

The climate has fluctuated throughout Earth’s history. Reconstruction of these past fluctuations are used to ground-truth current mathematical models for projecting future climatic changes. These model projections in turn, shape national and international political responses to the climate crisis. One of the major sources of information for reconstructing past climates is the make-up of fossilised shells of marine microbes called foraminifera. Correctly interpreting this fossil record requires knowledge of how environmental conditions exert control on the make-up of the foraminiferal shell during its formation. It also requires an understanding of the way foraminifera interact with other organisms in their environment, i.e. foraminiferal biology, because this too influences the shell make-up.

I have been researching the biology of a species of foraminifera called N. pachyderma. Because N. pachyderma is the only Arctic species, it is essential for understanding climate variation in that region. I have shown that this species eats bacteria and single celled plants called diatoms. Diatoms are abundant in Arctic seas, and N. pachyderma not only eats them, but also retains the diatom chloroplast – the part of the diatom that performs photosynthesis. The retention of chloroplasts, called kleptoplasty, has never been observed in open ocean foraminifera before. Because photosynthesis changes the make-up of foraminiferal shells, we need to know if the chloroplasts retained inside the foraminifera continue to carry out photosynthesis or not. We also need to know if kleptoplasty occurs in all N. pachyderma populations. For example does it occur in N. pachyderma living in the warmer waters of the North Pacific Ocean, or is it an adaptation by the Arctic population to survive the long winters?