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Schematic representation of Posidonia oceanica
Posidonia is not an algae, but a species of aquatic flowering plant endemic to the Mediterranean Sea (Boudouresque et al., 1984). It grows between the surface and 30 to 40 m depth, forming large meadows (Picard and Molinier, 1952), and constituting key ecosystems playing a major ecological role (Campagne et al., 2015; Gacia and Duarte, 2001; Mangos et al., 2010).
Posidonia oceanica plays an important role in the carbon cycle, particularly in the storage of anthropogenic carbon on the ocean floor. It is estimated that total carbon production by P. oceanica meadows is 3.5 million tonnes, of which 2.4 million tonnes is exported and stored (Pergent et al., 1997).
It reproduces both by sexual reproduction (with flowers and seeds) and by asexual reproduction (by the extension of rhizomes). Temperatures above 27◦C cause significant flowering, a sign of the plant's reaction to high heat (Diaz-Almela et al., 2007; Marín-Guirao et al., 2019; Ruiz et al., 2018).
Anthropogenic activity has been shown to have a negative impact on the development and maintenance of Posidonia meadows (McDonald et al., 2023). Despite legislation, Posidonia meadows are declining rapidly (34% over the last 50 years), showing that this widespread phenomenon should be attributed mainly to the cumulative effects of multiple stress factors (Telesca et al., 2015).
Posidonia recovers very slowly from these disturbances and could take decades to centuries to recover from its losses. Given their vital role in the ecological structure of the coast, it is crucial to protect these meadows from anthropogenic fragmentation to ensure the resilience of these ecosystems in the face of the climate crisis (Marco-Méndez et al., 2024).
Posidonia oceanica washed up on the beach after a storm, Var, France. Personal picture, March 2025.
Bibliography / Bibliographie
Boudouresque, C. F., Perret-Boudouresque, M., and Knoepffler-Peguy, M.: Inventaire des algues marines benthiques dans les pyrénées-orientales (méditerranéee, France), vie et Milieu/Life and environment, 49–51, 1984.
Campagne, C. S., Salles, J.-M., Boissery, P., and Deter, J.: The seagrass Posidonia oceanica : Ecosystem services identification and economic evaluation of goods and benefits, Marine Pollution Bulletin, 97, 391–400, https://doi.org/10.1016/j.marpolbul.2015.05.061, 2015.
Cebrian, J. and Duarte, C. M.: Detrital stocks and dynamics of the seagrass Posidonia oceanica (L.) Delile in the Spanish Mediterranean, Aquatic Botany, 70, 295–309, https://doi.org/10.1016/S0304-3770(01)00154-1, 2001.
Diaz‐Almela, E., Marbà, N., and Duarte, C. M.: Consequences of Mediterranean warming events in seagrass ( Posidonia oceanica ) flowering records, Global Change Biology, 13, 224–235, https://doi.org/10.1111/j.1365-2486.2006.01260.x, 2007.
Gacia, E. and Duarte, C. M.: Sediment Retention by a Mediterranean Posidonia oceanica Meadow: The Balance between Deposition and Resuspension, Estuarine, Coastal and Shelf Science, 52, 505–514, https://doi.org/10.1006/ecss.2000.0753, 2001.
Mangos, A., Bassino, J.-P., and Sauzade, D.: Valeur e ́conomique des benefices soutenables provenant des ecosystèmes marins méditerranéens. Centre d’activite ́s re ́gionales du PNUE/PAM., Les Cahiers du Plan Bleu, 8, 2010.
Marco-Méndez, C., Marbà, N., Amores, Á., Romero, J., Minguito-Frutos, M., García, M., Pagès, J. F., Prado, P., Boada, J., Sánchez-Lizaso, J. L., Ruiz, J. M., Muñoz-Ramos, G., Sanmartí, N., Mayol, E., Buñuel, X., Bernardeau-Esteller, J., Navarro-Martinez, P. C., Marín-Guirao, L., Morell, C., Wesselmann, M., Font, R., Hendriks, I. E., Seglar, X., Camps-Castella, J., Bonfill, E., Requena-Gutiérrez, A., Blanco-Murillo, F., Aguilar-Escribano, J., Jimenez-Gutierrez, S., Martínez-Vidal, J., Guillén, J. E., Cefalì, M. E., Pérez, M., Marcos, M., and Alcoverro, T.: Evaluating the extent and impact of the extreme Storm Gloria on Posidonia oceanica seagrass meadows, Science of The Total Environment, 908, 168404, https://doi.org/10.1016/j.scitotenv.2023.168404, 2024.
Marín‐Guirao, L., Entrambasaguas, L., Ruiz, J. M., and Procaccini, G.: Heat‐stress induced flowering can be a potential adaptive response to ocean warming for the iconic seagrass Posidonia oceanica, Molecular Ecology, 28, 2486–2501, https://doi.org/10.1111/mec.15089, 2019.
Mayot, N., Boudouresque, C.-F., and Leriche, A.: Unexpected response of the seagrass Posidonia oceanica to a warm-water episode in the North Western Mediterranean Sea, Comptes Rendus. Biologies, 328, 291–296, https://doi.org/10.1016/j.crvi.2005.01.005, 2005.
McDonald, A. M., McDonald, R. B., Cebrian, J., and Sánchez Lizaso, J. L.: Reconstructed life history metrics of the iconic seagrass Posidonia oceanica (L.) detect localized anthropogenic disturbance signatures, Marine Environmental Research, 186, 105901, https://doi.org/10.1016/j.marenvres.2023.105901, 2023.
Pergent, G., Romero, J., Pergent-Martini, C., Mateo, M. A., and Boudouresque, C. F.: Primary production, stocks and fluxes in the Mediterranean seagrass Posidonia oceanica., Marine Ecology, Progress Series, 139–146, 1994.
Pergent, G., Rico-Raimondino, V., and Pergent-Martini, C.: Fate of primary production in Posidonia oceanica meadows of the Mediterranean, Aquatic Botany, 59, 307–321, https://doi.org/10.1016/S0304-3770(97)00052-1, 1997.
Picard, J. and Molinier, R.: Recherches sur les herbiers de Phanérogames marines du littoral méditerranéen français., Masson, 1952.
Ruiz, J. M., Marín-Guirao, L., García-Muñoz, R., Ramos-Segura, A., Bernardeau-Esteller, J., Pérez, M., Sanmartí, N., Ontoria, Y., Romero, J., Arthur, R., Alcoverro, T., and Procaccini, G.: Experimental evidence of warming-induced flowering in the Mediterranean seagrass Posidonia oceanica, Marine Pollution Bulletin, 134, 49–54, https://doi.org/10.1016/j.marpolbul.2017.10.037, 2018.
Telesca, L., Belluscio, A., Criscoli, A., Ardizzone, G., Apostolaki, E. T., Fraschetti, S., Gristina, M., Knittweis, L., Martin, C. S., Pergent, G., Alagna, A., Badalamenti, F., Garofalo, G., Gerakaris, V., Louise Pace, M., Pergent-Martini, C., and Salomidi, M.: Seagrass meadows (Posidonia oceanica) distribution and trajectories of change, Sci Rep, 5, 12505, https://doi.org/10.1038/srep12505, 2015.
May 2025
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