In its typical state, the buoyant macroalgae known as Sargassum spp. serves as a vital habitat for a diverse array of organisms. Nevertheless, the emergence of the Great Atlantic Sargassum Belt (GASB) in 2011 has unleashed unparalleled surges of this brown seaweed onto Caribbean coastlines, triggering detrimental impacts on local ecosystems. This inundation poses a multifaceted challenge to the region's economies and tourism sector, while raising concerns about the potential repercussions for human health, particularly in terms of respiratory ailments and related issues.
Published in Nature Communications, the study "Nutrient and arsenic biogeochemistry of Sargassum in the western Atlantic" establishes that the nutrient content of Sargassum tissue plays a pivotal role in understanding the GASB. The research demonstrates that Sargassum in the GASB is enriched in both nitrogen and phosphorus, indicative of a thriving population. Stable nitrogen isotope values suggest riverine sources, shedding light on the nutrient origins.
Distinguishing the various nutrient sources that sustain the GASB is a complex task. Upwelling, vertical mixing, discharge from the Amazon and Congo rivers, and atmospheric deposition have been suggested as potential contributors. However, the precise causes of the GASB and the mechanisms controlling its variability remain unknown.
The study also reveals that Sargassum in the GASB displays higher nitrogen and phosphorus content than its counterparts residing in the Sargasso Sea. This discrepancy highlights the nutrient-driven nature of GASB inundations.
Aside from nitrogen and phosphorus, the study notes the presence of arsenic in Sargassum tissue, reflecting phosphorus limitation. This finding significantly impacts the utilization of seaweed biomass that washes ashore and should be considered in plans to address Sargassum inundations.
The GASB's growth over the last decade has garnered public attention due to its impact on coastal communities. Dennis McGillicuddy, Jr., the lead author of the study, emphasizes that understanding the situation is crucial, not only from a scientific perspective but also for the benefit of society. The overabundance of Sargassum has consequences for the environment, economy, and human health.
The study recommends expanded observational and modeling studies to comprehend the physical, biological, and chemical drivers of the GASB. With the urgency of the situation, improved predictions and an understanding of the underlying causes are essential for proactive planning and response.
McGillicuddy and co-author Brian Lapointe underscore the importance of interdisciplinary and collaborative research. Understanding the complex phenomenon of the GASB requires the expertise of various disciplines, including biology, chemistry, and physics.
The GASB phenomenon has disrupted the equilibrium of the tropical Atlantic, posing multifaceted challenges to society. By identifying nutrients as a driving force behind the GASB, this study paves the way for further research and potential mitigation efforts. Collaborative efforts and interdisciplinary research are key to addressing this ecological enigma and finding sustainable solutions.
Recent articles in E+E Leader have shed light on the burgeoning interest in Sargassum and its diverse potential applications.
Scientists and entrepreneurs alike are exploring ways to harness the abundance of Sargassum for positive environmental and economic impacts. One promising avenue is the extraction of valuable compounds from Sargassum, such as biofuels, biodegradable plastics, and specialty chemicals. Additionally, researchers are investigating its use in sustainable agriculture as a nutrient-rich soil conditioner. Sargassum's unique composition also makes it a candidate for carbon sequestration, which could help mitigate climate change. With ongoing efforts to develop innovative technologies and sustainable practices, Sargassum is poised to become a valuable resource with numerous eco-friendly applications.
The research was made possible through funding from the National Science Foundation, the National Institute of Environmental Health Sciences, WHOI, the Isham Family Charitable Fund, the State of Florida, and NASA. Sargassum samples were collected on U.S. GO-SHIP lines A20 and A22, supported by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration.
