1,721,038 research outputs found
Policies applying to Posidonia oceanica meadows. in Boudouresque C.F., Bernard G., Bonhomme P., Charbonnel E. Diviacco G. Meinesz A., Pergent-Martini C. Ruitton S, Tunesi L. (eds.) Ramoge and RAC/SPA and GIS publiscer Tunis pagg 48-60 ISBN 2-905540-31-1 http://www.rac-spa.org/sites/default/files/doc_vegetation/ramoge_en.pdf
No full textCaulerpa taxifolia: un'alga alloctona di oroigine tropicale dotata di elevate capacità invasive
No full textImpatto sull'ecosistema costiero mediterraneo da parte dell'alga verde tossica, Caulerpa taxifolia, di origine tropicale
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Nouvelles connaissances sur les herbiers tigres de Mediterranee
No full textRésumé
Les herbiers à Posidonia oceanica présentent plusieurs types morpho-structuraux
généralement conditionnés par les conditions de milieu (profondeur, hydrodynamisme,
substrat, pente, turbidité, sédimentation). Du fait de leur rareté, deux structures
particulières, les récifs barrière et les herbiers tigrés, sont considérées depuis une
vingtaine d’années comme des paysages marins menacés. Initialement décrits dans le
golfe de Gabés, à proximité des îles Kerkennah, les herbiers tigrés se présentent sous
forme « de rubans assez étroits qui se développent entre 0.5 et 3 m de profondeur sur
matte ». La mise en place de nouveaux programmes d’études sur les herbiers à
Posidonia oceanica et l’optimisation de l’imagerie satellitaire (accessibilité, résolution,
coût) ont permis d’acquérir de nombreuses données dans plusieurs secteurs de
Méditerranée et d’actualiser notre connaissance de ces structures.
Il apparaît ainsi que les herbiers tigrés sont mieux représentés au niveau de la rive Sud
du bassin (Golfe de Gabès, littoral de Zarzis en Tunisie, lagune de Farwa et littoral à
l’Est de Tripoli en Libye) et dans des îles méditerranéennes (Marsala-Stagnone en
Sicile et Porto-Vecchio en Corse). D’autre part la présence d’herbiers tigrés sur roche
a été observée pour la première fois en Libye sur un platier rocheux à l’Est de Tripoli.
Compte tenu de leur rareté et des pressions qu’elles subissent, il apparaît urgent de
classer ces structures comme « monuments naturels » et mettre en œuvre une politique
efficace pour assurer leur conservatio
The resilience of transplanted seagrass traits encourages detection of restoration success
Get PDFRestoration of coastal ecosystems, particularly those dominated by seagrasses, has become a priority to recover the important ecosystem services they provide. However, assessing restoration outcomes as a success or failure remains still difficult, probably due to the unique features of seagrass species and the wide portfolio of practices used on transplanting actions. Here, several traits (maximum leaf length, number of leaves, leaf growth rate per shoot, and leaf elemental carbon and nitrogen contents) of transplanted seagrass Posidonia oceanica were compared to reference meadows in five sites of Western Mediterranean Sea in which restoration were completed in different times. Results have evidenced the resilience of transplanted P. oceanica shoots within a few years since restoration, as traits between treatments changed depending on the elapsed time since settlement. The highlighted stability of the restoration time effect suggests that the recovery of the plants is expected in four years after transplanting
Spatially Explicit Seagrass Extent Mapping Across the Entire Mediterranean
No full textThe seagrass Posidonia oceanica is the main habitat-forming species of the coastal Mediterranean, providing millennial-scale ecosystem services including habitat provisioning, biodiversity maintenance, food security, coastal protection, and carbon sequestration. Meadows of this endemic seagrass species represent the largest carbon storage among seagrasses around the world, largely contributing to global blue carbon stocks. Yet, the slow growth of this temperate species and the extreme projected temperature and sea-level rise due to climate change increase the risk of reduction and loss of these services. Currently, there are knowledge gaps in its basin-wide spatially explicit extent and relevant accounting, therefore accurate and efficient mapping of its distribution and trajectories of change is needed. Here, we leveraged contemporary advances in Earth Observation-cloud computing, open satellite data, and machine learning-with field observations through a cloud-native geoprocessing framework to account the spatially explicit ecosystem extent of P. oceanica seagrass across its full bioregional scale. Employing 279,186 Sentinel-2 satellite images between 2015 and 2019, and a human-labeled training dataset of 62,928 pixels, we mapped 19,020 km(2) of P. oceanica meadows up to 25 m of depth in 22 Mediterranean countries, across a total seabed area of 56,783 km(2). Using 2,480 independent, field-based points, we observe an overall accuracy of 72%. We include and discuss global and region-specific seagrass blue carbon stocks using our bioregional seagrass extent estimate. As reference data collections, remote sensing technology and biophysical modelling improve and coalesce, such spatial ecosystem extent accounts could further support physical and monetary accounting of seagrass condition and ecosystem services, like blue carbon and coastal biodiversity. We envisage that effective policy uptake of these holistic seagrass accounts in national climate strategies and financing could accelerate transparent natural climate solutions and coastal resilience, far beyond the physical location of seagrass beds
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