Exploring the effects of anthropogenic changes on deep-sea abyssal plain and seamount benthic ecosystems in the North Atlantic using in-situ experimentation and modelling

About the Project

Oceanic food webs are among the most biologically productive systems on Earth and provide critical ecosystem services to humankind including food, climate regulation, nutrient cycling, and fisheries. Critical to their functioning, health, and the biodiversity they support are several globally significant processes. Oceanic food webs are fuelled by the biological carbon pump (BCP) that cycles food between the surface and seafloor through benthic-pelagic coupling. This supports energy flow through a food web from microbes to marine mammals. The mesopelagic zone (200-1,000m deep), is the vital link between the surface and seafloor. Food web health and biodiversity depend on maintaining this link through carbon flow to and from mesopelagic species, including fish, squid, microbes, and zooplankton.

Oceanic food webs are currently impacted by many anthropogenic activities, particularly climate-driven ocean changes, and fisheries that remove carbon (C) and high trophic level biomass and can impact non-target species. Moreover, threats such as those from deep-sea mining are expanding. Impacts from these will extend across all trophic levels and far deeper into the water column and down to the seafloor, but our understanding of the systems and impacts are mostly conceptual, with little attention paid to the actual processes supporting ocean health and functioning.

One management tool that can help protect and limit damage to marine ecosystems is the implementation of Marine Protected Areas (MPAs). OSPAR’s most recent MPA is the North Atlantic Current and Evlanov Sea basin (NACES) MPA. While the NACES MPA encompasses protection from the surface to the seafloor, our understanding of the NACES deep-sea ecosystems are extremely poor. As such, it is presently not possible to assess how effective the NACES MPA is with regards to preserving deep-sea biodiversity and ecosystem function in the NW Atlantic.

The PhD will be embedded within the EC Ocean SOS project and measure benthic C-demand at the abyssal seafloor and on seamounts using benthic respirometer landers, as well as microprofilers, and Aquatic Eddy Covariance systems. To document C flow through the benthos, stable isotope pulse-chase experiments will be undertaken in-situ. Biodiversity and C-flow to seafloor scavengers will be documented using baited camera landers and baited trap systems, specifically designed to be deployed to the relatively flat abyssal plain, as well as on more rugged terrain found on seamounts. Combining the aforementioned observations as well as observations on C-fluxes from sediment trap moorings will allow us to create novel linear inverse models (LIMs) of C-flows between the pelagic and benthic zones representing NACES. Ultimately, these LIMs will be forced by inputs from short-, medium-, and long-term scenarios of climate change and fisheries pressure (e.g., changes in C-input) to see how benthic ecosystem functions are maintained or altered in a anthropogenically-stressed ocean.

Director of Studies: Prof. Andrew K. Sweetman (SAMS)

Supervisory Team: Prof. Bhavani Narayanswamy (SAMS), Dr Emma Cavan (Imperial College London) and Dr Henk Jan Hoving (Geomar)

CONTACT:

Who can an applicant contact for further information about the project? Prof. Andrew K. Sweetman

Who can an applicant contact for further information about the application process? SAMS Graduate School: phd@sams.ac.uk

SCHEDULE:

Closing Date for Applications: Friday 22nd May 2026

Interview Date: Thursday 18th June 2026 (morning) Location: In person at SAMS

Start Date: 1st October 2026

ELIGIBILITY: [eligibility text]

HOW TO APPLY: [how to apply text]

Funding Notes

This is a 3.5-year PhD studentship, funded by the European Commission funded project ‘Ocean SOS’. Funding follows UKRI funding guidance and will cover UHI tuition fees and a maintenance stipend for a Home, EU or International student for 3.5 years.