Determining the origins and ages of plastic arriving on Scotland's shoreline

Marine litter is a global problem with, as yet, no solution(1). At the start of the Decade of the Ocean, we are still collectively generating around 13 million tonnes of plastic waste from terrestrial and marine industries, that ultimately end up in our seas and the global ocean each year. These extraordinary quantities of enduring plastic litter are becoming increasingly well documented, along with the resulting range of ecological, economic, and human health impacts.

Current research indicates that there are numerous litter accumulation “hotspots” but also “coldspots” on beaches around Scotland’s west coast mainland and islands. The idea of “litter sinks” as places where geography and topology combine with dominant currents and winds to capture excessive amounts of marine litter has been well-established. The natural counterpoint of these would be “litter sources” – places where tides, currents and winds remove litter and transport it elsewhere – has yet to be explored. Observations suggest that some objects travel significant distances across the Irish and Celtic Seas and the Atlantic Ocean to reach Scotland’s coastline.

Materials that are deposited and accumulate along coastlines can vary greatly from location to location. Different sources and activities not only influence this variation, but also by processes such as physical separation driven by a combination of material properties e.g., buoyancy and size and environmental factors e.g., coastal topography and ocean currents. Consequently, one stretch of shoreline might primarily consist of large debris like fish boxes, ropes, and strapping, while another nearby location may primarily accumulate smaller items such as bottle caps and shotgun cartridges. It is essential that this variability is understood in order to develop strategies that are tailored to local conditions — both for the effective cleanup of existing waste as well as preventing further pollution of our seas and ocean.

The initial research will focus on understanding marine litter conditions in Oban (Argyll) and near to Dumfries (Dumfries and Galloway), situated on the West coast of Scotland based on the most recent scientific and third-sector observations(2,3). The combined topology, geography, currents, weather and population densities/remoteness means that this region hosts litter sinks where large quantities of rubbish have accumulated, untouched for decades, and/or where large amounts of rubbish accumulate during each winter storm season. Many of the foreshores are cobbled but do also include stretches of sand and marram grass, thus presenting different surfaces and conditions to study how litter is trapped, retained and released. The west coast has significant local marine industry activity including fishing and aquaculture. However, it is also exposed to materials coming from further afield, with beached objects identified as originating from the Isle of Man, the island of Ireland, southern European and American Atlantic coasts and coastal water(3).

The initial survey will be conducted based on some of the OSPAR protocols. Drones will be flown (where possible) to obtain an overview of the area of interest, followed by stills images being captured every ~2 – 5 m using a standard digital camera. Regular observations will be undertaken documenting the arrivals, movement and departures of litter items. This will be combined with investigating the beaches pre- and post- storm events to evaluate changes. Comparisons will be made between the two regions of interest. Methods will be developed at SAMS to estimate the origins and ages of materials where possible based on litter items already collected. For example, patterns of distribution (e.g., clusters of domestic debris) may indicate the erosion of a previously buried midden; and manufacturers’ marks and branding can help identify the origins and ages of some items. Degrees and types of biomass accumulation on fishing/aquaculture gear may also provide information on time spent in the ocean environment and origins, e.g., the size of bivalves or the presence of non-native species.

The student will be required to be based at SAMS, Oban.

References:

1 Gonçalves GRL, Koomson A, Aggrey-Fynn J, Nyarko BK, Narayanaswamy BE. (2025) Invisible Peril: Assessing microplastic pollution in Ghanaian mangroves. Marine Pollution Bulletin. 211; 117361. https://doi.org/10.1016/j.marpolbul.2024.117361 

2 Allison et al. (2023). https://doi.org/10.1016/j.marpolbul.2023.115341

3 Scottish Islands Marine Litter Surveys 2023 - https://www.sifmarinelitter.co.uk/_files/ugd/55008e_f6ffbd37245844458d73bd6d2b8a5034.pdf

Director of Studies: Professor Bhavani Narayanaswamy (SAMS)

Supervisory Team: Dr Anna Wilson (University of Glasgow), Dr Geslaine Lemos Gonçalves – Plastic pollution specialist

Application Deadline: 7th January 2026

Interview date: 22nd January 2026

Start Date: March 2026

For further information about the project, please contact: Professor Bhavani Narayanaswamy Bhavani.Narayanaswamy@sams.ac.uk

For further information about the application process or funding, please contact: masters@sams.ac.uk

For further information about the MRes Marine Science, please contact Dr Bernadette Snow, Programme Lead:  Bernadette.Snow@sams.ac.uk