From oil spills to invasive species: Lagrangian modelling of connectivity in the Arctic Ocean

Marine connectivity describes the spatial and temporal linkages between separated parts of the global ocean. How different regions are connected, on what timescales, and by which oceanic pathways are important questions for a wide variety of applications. Answering these questions is an inherently interdisciplinary problem, with techniques including in-situ observations, remote sensing, and modelling used in synergy to answer key scientific questions. Here, a modelling approach is employed to contribute to our understanding of the wider field. This thesis focuses on understanding the importance of marine connectivity in the Arctic Ocean. The Arctic is a particularly important part of the global ocean, not least because of the impacts of climate change and loss of sea ice. This presents both challenges and opportunities - for instance, the retreat of Arctic sea ice is increasing interest in exploiting the region for resource extraction and commercial shipping, and changing circulation associated with a warming Arctic may permit invasive species to traverse the ocean. These and other drivers motivate research into how connectivity is shaping the ecological, physical, and socioeconomic features of the Arctic Ocean. Primarily using a Lagrangian particle-tracking technique in conjunction with a state of the art, eddy-permitting ocean model, three case studies – one biological, one physical and one socioeconomic – are used to explore the impact of marine connectivity in the Arctic Ocean. These studies respectively focus on: 1. Exploring the change in connectivity between the Beaufort Gyre and the sources of its freshwater contribution (Kelly et al., 2019); and 2. Investigating the spread of pollutants in the event of a shipping accident from the Northern Sea Route (Kelly et al.,iv2018); 3. Assessing the role of changing advective pathways linking the Pacific and Atlantic Oceans on potential invasive species to the North Atlantic (Kelly et al., 2020). Individually, each paper addresses one specific aspect of Arctic connectivity. As chapters of a the-sis, they are designed to illustrate the importance of marine connectivity in linking physical, biological and socioeconomic factors in a rapidly changing Arctic Ocean