Predicting growth and survival of holopelagic Sargassum using a mechanistic model under different environmental scenarios

Since 2011 unprecedented quantities of holopelagic Sargassum morphotypes have been observed in the tropical Atlantic, resulting in economic, health, and ecological consequences. These events, characterized by large biomass aggregation spreading across the tropical Atlantic and later stranding along coastline, have been studied to understand the spatio-temporal variability of Sargassum morphotypes. While current models provide insights into the advection, there is little understanding on the mechanisms behind the response to current environmental conditions. In order to identify and explicitly quantify Sargassum’s trade offs between the changing ocean conditions, we developed a multi reserves DEB (Dynamic Energy Budget) model. Using the DEB framework, we simulate Sargassum’s nutrient uptake and thermal response under different environmental scenarios representing the conditions encountered by Sargassum along their drift. Parameters for the model are estimated and validated through comparison with experimental data.

 

As a part of the BIOMAS project (BIOenergetic Modeling Approach for Sargassum dynamics), this DEB model will be integrated into a drift model to simulate Sargassum sp. proliferation on a seasonal scale and across multiple years. This approach aims to improve our understanding of the interplay between the biological and physical factors driving Sargassum morphotypes dispersal and biomass proliferation. In such a manner, improving bloom predictions will support local communities by understanding Sargassum occurrences therefore mitigating the impacts of these events.