Drift bottle data hint at large-scale ocean circulation changes

• Published in: Frontiers in Marine Science
• Main Authors: Natasha A. Ridenour, Liam Buchart, Eddy Carmack, Inge Deschepper, Eric Galbraith, Geoff Green, Juliana M. Marson, Clark Pennelly, Tahya Weiss-Gibbons, Paul G. Myers
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2023
• Subjects: ocean modelling; drift bottles; North Atlantic; citizen science; subpolar gyre; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Arctic; Canada; Norway; Soi
• Online Access: https://doi.org/10.3389/fmars.2023.1227894; https://doaj.org/article/700cb4548b6d47a8a3400e116e7dacde

Over the last two decades, in an effort to engage youth in polar science, the Students On Ice (SOI; https://studentsonice.com/) project has become a platform for youth to partake in scientific expeditions around the globe. Among the various activities offered, youth are able to join cruises in the North Atlantic or Arctic, and drop sealed glass bottles into the ocean. Of the thousands that have been deployed, 5% of bottles have been recovered and reported back to SOI with details on when and where they were found. Here, we compare the observational bottle data with virtual particle trajectories from a high resolution regional ocean model. Although modelling results indicate a higher likelihood of bottles reaching the shores of the western Atlantic, the majority of recovered bottles were found on the eastern side of the Atlantic. We attribute this disparity to differences in population density in Canada and Europe, biasing the recovery rates. Despite this bias, we find that changes in recovery locations over time are consistent with changes in the main ocean currents associated with the contraction and expansion of the North Atlantic Subpolar Gyre, as simulated in our ocean model. In 2007, a large number of bottles were found in Norway, coinciding with a contracted North Atlantic Subpolar Gyre during 2004-2008. While between 2012-2016, the majority of bottles were recovered on the British Isles, during a time of gyre expansion. These results underline the importance of large scale oceanic cycles for tracking marine debris and pollution, and show how even simple data collection methods, such as drift bottles, can provide clues to the changes in the large scale ocean circulation.