The proliferation of holopelagic Sargassum in the Atlantic Ocean and Caribbean Sea has significant ecological, economic, and environmental impacts. This session aims to bring together researchers from the international community to share their latest research on the causes, origins, and predictability of Sargassum accumulation and stranding events. The session will focus on several key areas to increase our knowledge and understanding of Sargassum ecology: 1. Insights into the genetic diversity of Sargassum across the Atlantic, including microbiome and geographic distribution, 2. Examination of the role of nutrient inputs from diverse sources, such as Amazon river outflow, upwelling systems, and atmospheric deposition (e.g., Saharan dust), in stimulating Sargassum growth, 3. Exploration of changing ocean currents and temperature on the patterns of distribution and intensity of Sargassum accumulations. 4. Development of models and predictive tools to forecast bloom events, integrating data from satellite observations, oceanographic measurements, and climate models to improve the accuracy of bloom predictions. 5. Assessment of the ecological consequences of large-scale Sargassum events on marine ecosystems, including impacts on biodiversity, fisheries, and coastal environments.
Lead Organizer: Fabio Nauer, Royal Netherlands Institute for Sea Research (NIOZ) (fabio.nauer@nioz.nl)
Co-organizers:
Linda Amaral-Zettler, Royal Netherlands Institute for Sea Research (NIOZ) (linda.amaral-zettler@nioz.nl)
Pierre-Yves Pascal, Université des Antilles (pierreyves.pascal@gmail.com)
Presentations
06:00 PM
In Situ Monitoring of a Sargassum Mat Using a Novel Drifter in the Great Atlantic Sargassum Belt (GASB) (9094)
Primary Presenter: Elizabeth Gower, MIT-WHOI Joint Program (elizabeth.gower@whoi.edu)
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.
06:00 PM
SELECTIVE UPTAKE OF BIOACTIVE TRACE ELEMENTS BY ATLANTIC SARGASSUM (9225)
Primary Presenter: Riley Stallings, Texas A&M University (rileyastall@tamu.edu)
The Great Atlantic Sargassum Belt spans the width of the Atlantic Ocean, extending from western Africa and into the Gulf of Mexico. Coastal regions are especially vulnerable to potential hazards resulting from nearshore Sargassum inundation, including the release of potential toxicants during the degradation of massive accumulations of seaweed biomass. Few published studies have included the trace element composition of Sargassum, but those that have highlight the importance of bioactive trace elements (both nutrient and toxicant) to the growth of Sargassum. Here, we present the initial results of an intensive field campaign to investigate the trace element concentrations in ~1000 samples of Sargassum collected from the beaches and coastal waters of Florida, USA (June 2023-August 2024). Special care was taken throughout the sampling and analysis process to minimize contamination and optimize the determination of major and trace elements in the Sargassum, including the use of high precision balances and antistatic devices, multiple certified reference materials, and instrumental quantitation methods to account for matrix effects. Our ongoing analyses have already confirmed the close relationship between potentially toxic trace elements like As and imbalances in the elemental ratios of major nutrients like N and P in Sargassum biomass. Our presentation will describe the application of an expanded suite of bioactive elements (including oxyanions) which indicate uptake mechanisms by Sargassum under different nutrient deplete or replete conditions in a natural setting.
06:00 PM
Design and implementation of a citizen science and static camera imagery processing system for coastal sargassum monitoring. (9624)
Primary Presenter: Jose Antonio Lopez Portillo Hurtado, Universidad Nacional Autonoma de México (avtovio23@gmail.com)
The continuous arrival of sargassum to the coasts of the Mexican Caribbean has caused significant environmental and economic damage, increasing the need for continuous and detailed coastal monitoring that is also easy and inexpensive to implement, making it more attractive for broader adoption. In this work, we present the design and implementation of a system capable of analyzing images obtained through citizen science and static cameras to gather information about the quantity and frequency of sargassum influx on the coast, providing insight into potential future impacts. The system can continuously and automatically analyze images from fixed cameras using image processing and neural networks. Subsequently, using images from the citizen science program, the system classifies sargassum in its different stages of decomposition, both near and along the coast. Since sargassum needs to be collected as fresh as possible, the information obtained from this system allows for proper evaluation to prioritize the most affected areas and implement actions to help mitigate the damage.
06:00 PM
HEALTH RISKS FROM STRANDED SARGASSUM (9735)
Primary Presenter: Helena Solo-Gabriele, University of Miami, Coral Gables, FL (hmsolo@miami.edu)
Potential health risks from Sargassum strandings include exposures to arsenic, infectious microbes, and hydrogen sulfide. This study explores environmental levels of arsenic, pathogenic microbes, and sulfer releases from stranded Sargassum. The elevated levels of arsenic are due to the bioaccumulation, pathogenic microbes especially Vibrio species vary depending upon stranding duration, and sulfer species are volatilized from Sargassum when waterlogged. This poster will introduce the health risks and focus on assessing arsenic. Arsenic levels were documented in Sargassum, sand, and water at five beaches. Mesocosm studies were conducted to evaluate the transport of arsenic from Sargassum, to sand, to water, and to the atmosphere. Results from mesocosm studies indicate that the majority of the arsenic volatilizes. The arsenic that remains in the stranded Sargassum can be a source of exposure. Using levels of arsenic found in Sargassum, sand, and water, along with human exposure factors indicates that cancer risks are on the order of 10-4, which is considered low increased risk. This risk to beach goers is driven by the dermal absorption factor.
SS31P - Sargassum Accumulations in the Atlantic: Ecological Drivers, Impacts, and Predictive Models
Description
Time: 6:00 PM
Date: 29/3/2025
Room: Exhibit Hall A