Clustering analysis of the Sargassum transport process: application to beaching prediction in the Lesser Antilles

Abstract

Abstract. The massive Sargassum algae beachings observed over the past decade are a new natural hazard currently impacting the island states of the Caribbean region (human health, environmental damages, and economic losses). This study aims to improve the prediction of the surface current dynamic leading to beachings in the Lesser Antilles using clustering analysis methods. The input surface currents were derived from the Mercator model and the Hybrid Coordinate Ocean Model (HYCOM) outputs in which we integrated the windage effect. Past daily observations of Sargassum beaching on Guadeloupe coasts and satellite-based Sargassum offshore abundance were also integrated. Four representative current regimes were identified for both Mercator and HYCOM data. The analysis of the current sequences leading to beachings showed that the recurrence of two current regimes is related to the beaching peaks respectively observed in March and August. The performance score of the predictive model showed that the HYCOM data seem more suitable to assess coastal Sargassum hazard in the Lesser Antilles. For 1 year of tests (i.e., 2021), the decision tree accuracy respectively reached 70.1 % and 58.2 % for HYCOM and Mercator with a temporal uncertainty range ±3 d around the forecast date. The present clustering analysis predictive system, requiring lower computational resources compared to conventional forecast models, would help improve this risk management in the islands of the region.

Haline Tolerance of Stomatopod (Crustacea) Larvae and Pelagic Dispersal of Two Common Species in the Western Atlantic

“…The cyclonic Panama-Colombia Gyre (Andrade-Amaya, 2001), could be the main responsible of this pattern. In the Lesser Antilles (sites 40-43) connectivity had a north direction, in agreement with a previous study showing the same pattern in the population connectivity of a coral species (Japaud et al, 2019); the rings separated from the North Brazil Current interact with the stepped topography of the Lesser Antilles causing a northward circulation pattern (Bernard et al, 2022). Southern Puerto Rico (site 45) showed a high self-recruitment value (16.7%) and potentially transferred a considerable quantity (15.3%) to site 46, located to the west.…”

Brown algae invasions and bloom events need routine monitoring for effective adaptation

“…Building on the need for further empirical evidence and modelling, recent literature has made significant advances in this area. Advanced statistical models, remote sensing and machine learning algorithms have been introduced to simulate algae events, taking into account a variety of environmental and anthropogenic factors [13,15,17,18]. Despite these advances, gaps in our knowledge still exist.…”

“…The severity of these emergent risks is difficult to predict, in part due to the complexity of the ecological processes and associated feedbacks between climate, natural and human systems [12]. The advances in science and technology are providing us with increasingly sophisticated tools to predict and simulate algae events, such as satellite remote sensing [13,14], machine learning algorithms [15,16], and oceanographic modelling [17,18]. This progress is improving our understanding of the complex factors that contribute to brown algae events.…”

A Framework for Frugal Supervised Learning with Incremental Neural Networks

“…Regarding unsupervised learning methods, recent techniques allow us to obtain interesting results from small datasets [17]. The integration of human expertise at an early stage of the training process favors effective analysis and interpretation [18].…”