Almost a century of monitoring of the Posidonia barrier reef at Port-Cros (Provence) and the platform reef at Saint-Florent (Corsica). - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2019

Almost a century of monitoring of the Posidonia barrier reef at Port-Cros (Provence) and the platform reef at Saint-Florent (Corsica).

Résumé

The dynamics of natural monuments such as the Posidonia oceanica reefs is poorly known. The Posidonia barrier-reef Port-Cros has served as a laboratory for Molinier and Picard back in the 1950s and enabled them to describe the process of building of P. oceanica fringing and barrierreefs, while the Saint-Florent platform-reef, mapped for the first time in the 1980s, appears to be a unique structure the construction of which remains a mystery. The availability of postcards dating from the early 20th century, aerial photographs dating from 1948, and the development of remote sensing and georeferencing techniques associated with the use of drones and 3D models, have made it possible to monitor, for the first time, the precise evolution of these reefs and associated structures. Since the early 20th century, the barrier-reef at Port-Cros has been undergoing a steady decline. Anthropogenic pressures more than natural pressures may underlie this regression. Despite a number of management measures aimed at its protection, regression of the barrier-reef continues inexorably, at an unchanged pace, such that its ultimate disappearance now seems predictable. With regard to the Saint-Florent platform-reef, the surface area covered by Posidonia oceanica has remained stable (around 2.5 ha), although some differences can be observed from year to year; essentially due to the quality and resolution of the aerial images used for analysis. Moreover, the main atoll observed on the platform has regularly increased in size, from 40 m2 in 1948 to the current 189 m2. The conservation of these natural monuments, both included within MPAs, must be given priority by environmental managers.
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Dates et versions

hal-02112066 , version 1 (26-04-2019)

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  • HAL Id : hal-02112066 , version 1

Citer

Alizée Boussard, Emeline Barralon, Charles F. Boudouresque, M. Boursault, Adrien Goujard, et al.. Almost a century of monitoring of the Posidonia barrier reef at Port-Cros (Provence) and the platform reef at Saint-Florent (Corsica).. 6th Mediterranean Symposium on Marine Vegetation, Jan 2019, Antalya, Turkey. ⟨hal-02112066⟩
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