In Situ Monitoring of a Sargassum Mat Using a Novel Drifter in the Great Atlantic Sargassum Belt (GASB)

Sargassum strandings significantly impact coastal ecosystems and economies. Understanding how they vary in terms of nutrients and densities will help us monitor ocean health and further our understanding of carbon dynamics. Here, we discuss results from instrumented Sargassum drifters that were deployed across the Great Atlantic Sargassum Belt (GASB) in the summer of 2024. Current Sargassum monitoring technologies, such as satellite mapping and existing drifters, collect low resolution location data and typically do not reveal information about the underlying biological processes of Sargassum patches. Localized measurements of oxygen (O₂) or carbon dioxide (CO₂) can be collected shipboard using a research vessel, but expeditions are expensive, time consuming, and have low spatial resolution. Here we present results of a drifter that was designed to entangle with Sargassum mats and outfitted with a suite of low-cost sensors for continuous, in situ collection of Sargassum density, partial pressure of CO₂ (pCO₂) and O₂, and temperature. The design uses an Iridium satellite to transmit data messages, requiring no human interference while operating. Three drifters were deployed in the summer of 2024 from the R/V Pelagia, providing four weeks of data that revealed changes in both dissolved O₂ and pCO₂ as the drifters traversed the Atlantic Ocean. These low-cost drifters have the potential to inform patch dynamics, increasing our understanding of Sargassum, carbon uptake and release, and the wider ocean impact associated with the GASB.

Presentation Preference: Poster

Primary Presenter: Elizabeth Gower, MIT-WHOI Joint Program (elizabeth.gower@whoi.edu)

Authors:

Elizabeth Gower, MIT-WHOI Joint Program in Oceanography/Applied OCean Science & Engineering  (elizabeth.gower@whoi.edu)

Chase Pixa, Woods Hole Oceanographic Institution  (cpixa@whoi.edu)

Sarah Youngs, Woods Hole Oceanographic Institution  (syoungs@whoi.edu)

Mary Burkitt-Gray, Woods Hole Oceanographic Institution  (mary.burkitt-gray@whoi.edu)

Spencer Marquardt, Woods Hole Oceanographic Institution  (spencer.marquardt@whoi.edu)

Linda Amaral-Zettler, NIOZ Royal Netherlands Institute for Sea Research  (linda.amaral-zettler@nioz.nl)

Erik Zettler, NIOZ Royal Netherlands Institute for Sea Research  (erik.zettler@nioz.nl)

Anna Michel, Woods Hole Oceanographic Institution  (amichel@whoi.edu)

William Pardis, Univeristy of California Berkeley  (wpardis@berkeley.edu)