CERMES: Sargassum Outlook Bulletin
“Our Sub-regional Sargassum Outlook Bulletin provides medium-range (3-monthly) island-scale forecasts of sargassum influxes to the Eastern Caribbean, based on our validated sargassum transport model from the new source region in the equatorial Atlantic. It also provides comment on sector-specific implications for tourism and fisheries stakeholders, and provides summaries and links to the latest sargassum papers and innovations. By simplifying scientific jargon so that stakeholders can easily understand and benefit from the forecasts, we anticipate that the bulletin will facilitate wider access to specifically tailored early warning information, thus allowing better decision-making by key socio-economic sectors in the Eastern Caribbean islands.”

Assessing growth of pelagic sargassum in the Tropical Atlantic
M Corbin, HA Oxenford in Aquatic Botany 187, 103654 “Pelagic sargassum species, historically endemic to the North Atlantic, have now been identified in the Tropical Atlantic. For over a decade, massive blooms of pelagic sargassum have dispersed seasonally from this ‘new’ Tropical Atlantic source region, negatively impacting the coasts of Caribbean and West African countries. Significant strides have been made towards adaptation to this new ‘hazard’, yet many knowledge gaps remain that constrain improvements to these efforts. The key objective of this study was to add to the knowledge of pelagic sargassum growth rates in the Tropical Atlantic to better inform forecasting and innovative applications. Growth rates of the three commonly occurring morphotypes from the Tropical Atlantic source region, S. fluitans III, S. natans I and S. natans VIII, were studied in-situ using novel ‘growth mesocosms’ in neritic waters of Barbados under cool and warm ambient conditions. Overall, results reveal a significant difference in growth rates among all pelagic sargassum morphotypes, with S. fluitans III on average doubling its biomass in 13 days, S. natans I in 22 days and S. natans VIII in 31 days. Furthermore, growth rates of S. fluitans III decreased significantly with an increase in ambient temperature from the cool (mean 27.6 °C) to warm (mean 29.6 °C) water period. During both periods S. fluitans III grew significantly faster than the other two morphotypes. However, S. natans I only grew significantly faster than its conspecific morphotype, S. natans VIII, during the cool period. These findings highlight the different growth responses among sargassum morphotypes under varying conditions and add to the considerable variability in growth rates reported by recent similar studies conducted elsewhere in the Tropical Atlantic. As such, it is clear that further research will be needed…”

Climate-sargassum interactions across scales in the tropical Atlantic
R Marsh et al., 2023 in PLOS Climate 2 (7), e0000253 “The impacts of climate change on ecosystems are highly uncertain but potentially profound. One such impact may be the emergence of extensive mats of seaweed (macroalgae), due to the extraordinary proliferation of pelagic sargassum species, in the tropical Atlantic since 2011. Sargassum blooms are now an annual event and reached record levels across what is now known as the ‘Great Atlantic Sargassum Belt’ (GASB) in summer 2022. Monitoring across scales, from satellite surveillance to in-situ beach surveys, is bringing step changes in process-level understanding of sargassum. Physical and biogeochemical drivers of sargassum act at basin scale to shape the GASB, highly variable from year to year. In the local environment, sargassum is sensitive to ambient conditions, with new findings confirming that growth rates are temperature dependent. Multidecadal ocean warming may therefore be detrimental to sargassum, although projected changes in other drivers are uncertain. Emerging options for climate change action around sargassum include valorisation and carbon sequestration, although uncertainties are again considerable. In conclusion, the emergence of sargassum across the tropical Atlantic highlights interconnected systems that embrace physical, biogeochemical, and socioeconomic dimensions, with considerable scope for improved monitoring, process-level understanding and prediction.”

CERMES: Sargassum
“Since 2011, huge volumes of sargassum seaweed have been periodically transported by ocean currents to the Caribbean. These unprecedented and hard-to-predict influxes of sargassum, linked to ocean eutrophication and climate change, are having devastating impacts on Caribbean coastal socio-ecological systems.” Page discusses topic under What’s the problem?, What has CERMES been up to?,What have we learned? What’s next?

Applying Hazard Risk Assessment and Spatial Planning Tools to Sargassum Inundations in the Eastern Caribbean Small Island States as a Basis for Improving Response
Degia. A.K., M. Small, H.A. Oxenford, 2022. A . SargAdapt Project Report, FINAL DRAFT. Centre for Resource Management and Environmental Studies (CERMES), University of the West Indies, Cave Hill, Barbados, 72pp.Details for Barbados under ANNEX 1 Country-Specific Sargassum Hazard and Exposure Mapping and Description p. 18
Barbados, pages 18-27.

Sargassum blooms are here for the foreseeable future 15Mar2023
Post on this website Mar 15, 2023.