Jón Tomas Magnússon (PhD).

Seaweed-associated biodiversity and changes after impact (PhD)

My research aims to better understand the diversity of kelp-associated species and how it is impacted by disturbances such as storms, climate change and other anthropogenic stressors. Specifically, it will investigate biodiversity at different recovery stages after harvesting, providing insight into commercial harvesting long-term effects. Furthermore, it will compare biodiversity across different habitat states to understand how species abundance, distribution and composition vary when kelp forests change. Another key objective is to evaluate how to best assess biodiversity in kelp canopies and the effectiveness of various methods, including SCUBA diving surveys, environmental DNA (eDNA), and other remote sensing. In addition, the project will explore how kelp-associated biodiversity responds to environmental changes using Arctic ecosystems as a proxy. Finally, the project will include a conceptual review and/or modelling exercise evaluating biodiversity metrics and their relevance for conservation under the biodiversity credit framework.

Supervisors: Albert Pessarrodona & Thomas Wernberg

Qualifications

2021: MSc Marine Biology (1^st class with distinction), University of Iceland, Iceland. Thesis: Mobile predators on the Ascophyllum nodosum dominated shores of Breiðafjörður, Iceland.
2018: BSc Environmental Biology, Autonomous University of Barcelona, Spain.

Peer Reviewed Publications

Magnússon, J. T.,Hawkins, S. J., Gunnarsdóttir, L., Svavarsson, J., & Gunnarsson, K. (2024). Range extension of invasive Cancer irroratus and native Carcinus maenas polewards in the Ascophyllum-dominated intertidal zone in north-west Iceland. Journal of the Marine Biological Association of the United Kingdom, 104, e3. https://doi.org/10.1017/S0025315423000905
Magnússon, J. T., Silva, A., Hawkins, S. J., Paula, J. P., Marques, T. A., & Boaventura, D. (2025). Spatial distribution of the intertidal limpet Patella depressa Pennant, 1777: Patterns across wave exposure and season. Journal of Experimental Marine Biology and Ecology, 582, 152073. https://doi.org/10.1016/j.jembe.2024.152073
Magnússon, J. T., Hawkins, S. J., Gunnarsdóttir, L., Svavarsson, J., & Gunnarsson, K. (2025). Icelandic intertidal fish communities and effects of knotted wrack (Ascophyllum nodosum) harvesting. Journal of the Marine Biological Association of the United Kingdom, 105, e75. https://doi.org/10.1017/S0025315425100301