The Lagrangian-based Floating Macroalgal Growth and Drift Model (FMGDM v1.0): application to the Yellow Sea green tide

Massive floating macroalgal blooms in the ocean result in many ecological consequences. Tracking their drifting pattern and predicting their biomass are essential for effective marine management. In this study, a physical–ecological model, the Floating Macroalgal Growth and Drift Model (FMGDM), was developed. Based on the tracking, replication, and extinction of Lagrangian particles, FMGDM is capable of determining the dynamic growth and drift pattern of floating macroalgae, with the position, velocity, quantity, and represented biomass of particles being updated synchronously between the tracking and the ecological modules. The particle tracking is driven by ocean flows and sea surface wind, and the ecological process is controlled by the temperature, irradiation, and nutrients. The flow and turbulence fields were provided by the unstructured grid Finite-Volume Community Ocean Model (FVCOM), and biological parameters were specified based on a culture experiment of Ulva prolifera, a phytoplankton species causing the largest worldwide bloom of green tide in the Yellow Sea, China. The FMGDM was applied to simulate the green tide around the Yellow Sea in 2014 and 2015. The model results, e.g., the distribution, and biomass of the green tide, were validated using the remote-sensing observation data. Given the prescribed spatial initialization from remote-sensing observations, the model was robust enough to reproduce the spatial and temporal developments of the green tide bloom and its extinction from early spring to late summer, with an accurate prediction for 7–8 d. With the support of the hydrodynamic model and biological macroalgae data, FMGDM can serve as a model tool to forecast floating macroalgal blooms in other regions.

Challenges and Opportunities in Relation to Sargassum Events Along the Caribbean Sea

Mass blooms and stranding of pelagic Sargassum spp. in the Atlantic, termed Sargassum events are becoming more frequent in response to several factors: nutrient enrichment, increased temperature, changes in climatological patterns, but some causes remain unknown. The magnitude of Sargassum events in the Caribbean Sea since 2011 make us aware of the necessity to tackle these events, and macroalgal blooms generally, not only locally but on a regional scale. At least three pelagic species of Sargassum have been dominant in the blooms that have occurred along Caribbean coastlines in great quantities. Due to the regional scale of these events and its complexity, its management should be based on basic and applied information generated by different collaborative actors (national and international) through interdisciplinary and transdisciplinary work. To address this, we propose different phases (exploratory, valorization, and management) and the approach for their study should include detection, collection, stabilization and experimentation. This information will help identify the potential applications and/or ecological services to develop for the exploitation and mitigation strategies in the region. Relevant challenges and opportunities are discussed, remarking on the necessity to evaluate the spatiotemporal variation in the abundance and chemical composition of floating and stranded biomass. The above-mentioned will provide management strategies and economic opportunities as possible solutions to their extensive impact in the Caribbean.