Professor Claire Mahaffey BSc, PhD

The ARISE project is looking at how environmental change affects Arctic food webs. We will use novel biological markers or ‘biomarkers’ present in phytoplankton and zooplankton at the base of the food chain and Arctic seals at the top of the food chain. The biomarkers will allow us to understand how well these parts of the food chain are connected and the extent to which the environment is altering the food chain as the Arctic climate changes. The data we collect during the project will contribute to larger datasets collected by our international collaborators across the Arctic. We will use output from statistical and biogeochemical models to assess how much change has occurred in the food webs across the Arctic and the reasons for the change.
More information can be found at:Changing Arctic Ocean Programme

This project was funded by UKRI NERC (2017 to 2022)

Phosphorus is an essential resource for life on earth due to its role in key cellular components. Marine phytoplankton have a metabolic preference towards the assimilation of inorganic phosphate. Due to excessive nitrogen addition via both natural and anthropogenic processes, the ocean is currently being driven towards phosphate limitation. This is exemplified in the subtropical North Atlantic, which has the lowest phosphate concentrations seen in the open ocean. The current view is that phosphate limitation is alleviated by production of enzymes that allow phytoplankton to access the abundant pool of dissolved organic phosphorus. However, recently work by our team has revealed that the activity of these phosphorus acquiring enzymes are limited by the availability of zinc. Other work suggests that iron may also limit these enzymes. These novel results point to the potential co-limitation of biological activity by phosphorus and zinc and/or iron. At present, estimates of future ocean productivity do not account for increasing the intensity and spatial extent phosphate limitation in the ocean but instead focus on a reduced supply of all nutrients by enhanced stratification. Our goal is to expand our initial work by combining observational and modelling experiments to identify the extent of zinc-phosphorus and iron-phosphorus co-limitation in the subtropical North Atlantic and quantify the impact of co-limitation between phosphate, zinc and iron on contemporary and end of century biological productivity. In doing so, we will challenge the current view of the drivers of long-term trends in the productivity of the subtropical ocean.


This project was funded by UKRI NERC (2017 to 2020)