Monitoring the temporal evolution of Posidonia oceanica banquettes: integrating historical imagery and coastal CCTV observations
1
Department of Science and Technology, Parthenope University of Naples, Centro Direzionale, Isola C4, Napoli, - 80143, Italia
2
Maths and Physics Building, Faculty of Science, University of Malta, Msida Campus, Tal-Qroqq, Msida, - 2080, Malta
Coastal management in the Mediterranean often prioritises beach usability for tourism over ecosystem functioning, leading to the routine removal of the stranded seagrass biomass. This reflects a broader mismatch between short-term tourism demands and the sustainable management of coastal ecosystems. However, Posidonia oceanica banquettes, accumulations of dead leaves along shorelines, play a key role in coastal protection by reducing coastal erosion, retaining sediments, and storing carbon. Their systematic removal and disposal as waste can therefore undermine coastal resilience and long-term sustainability.
In this context, we analyse nearly two decades (2009-2025) of banquette extent at Maltese beaches using historical Google Earth Pro imagery, comparing seasonally groomed sites against those left undisturbed. Preliminary results reveal that Xatt l-Aħmar (Gozo), never groomed, showed the most stable deposits (228-349 m²), while Pembroke, also not groomed, displayed the highest variability of all sites (294-1677 m²). Among groomed sites, St. Thomas Bay fluctuated between 485 and 906 m², settling around 580 m² recently, while Għajn Tuffieħa's sparse record (524 to 267 m²). Xemxija, though ungroomed, oscillated considerably (147-800 m²).
To overcome the discontinuous nature of satellite imagery, this study proposes the deployment of coastal CCTV cameras to provide continuous, high-frequency monitoring of banquette dynamics. The imagery will be integrated with wave, wind, and storm data obtained from the Copernicus Marine Service to investigate the environmental drivers influencing banquette accumulation and erosion. The monitoring programme will be complemented by field and laboratory analyses. Sediment samples collected from groomed and non-groomed beaches will be analysed to determine sediment organic carbon content, grain-size distribution, and heavy metal concentrations. By integrating historical satellite imagery, continuous CCTV monitoring, hydrodynamic data, and sediment analyses, this study aims to provide an evidence-based framework for understanding P.oceanica banquettes dynamics and supporting sustainable coastal management.
Capitale naturale, servizi ecosistemici e contabilità ambientale
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