Mass flowering of the seagrass Posidonia oceanica after 2022 record-breaking marine heatwaves, a Pan-Mediterranean study

Abstract Following the unprecedented marine heatwaves of summer 2022, extensive flowering of the endemic seagrass Posidonia oceanica was witnessed across the western Mediterranean. To unravel the causes of this event, we conducted a pan-Mediterranean analysis across 442 sites spanning all Mediterranean ecoregions, with 76% exhibiting flowering. Flowering differed regionally, with both highest flowering prevalence (over 90%) and flowering intensity (up to 0.75) recorded in the Liguro-Provençal and Balearic Seas. We demonstrate that regions experiencing large summer sea surface temperature anomaly with high marine heatwave cumulative intensity displayed the highest flowering intensity. The probability of flowering was very likely when marine heatwave cumulative intensity exceeded ⁓120°C days. These findings suggest that marine heatwaves trigger flowering in P. oceanica and, given the high energetic cost of sexual reproduction, continued ocean warming may shift energy allocation toward flowering. This shift could profoundly affect the species’ reproductive strategies, posing major challenges and uncertainties for its long-term evolution.

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Journal
Communications Earth & Environment
Published
2026-05-22
DOI
https://doi.org/10.1038/s43247-026-03631-8
Primary Topic
Marine and coastal plant biology
Type
article
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article

Mass flowering of the seagrass Posidonia oceanica after 2022 record-breaking marine heatwaves, a Pan-Mediterranean study

Eugenia T. Apostolaki, Candela Marco‐Méndez, Adrien Cheminée, Edoardo Casoli et al.
Communications Earth & Environment
Marine and coastal plant biology
article

Mass flowering of the seagrass Posidonia oceanica after 2022 record-breaking marine heatwaves, a Pan-Mediterranean study

Eugenia T. Apostolaki, Candela Marco‐Méndez, Adrien Cheminée, Edoardo Casoli, Neus Sanmartí Boixeda, Carla Morri, Fabio Badalamenti, Arianna Pansini, Arnaud Boulenger, Ilaria Mancini, Vesna Mačić, Nathaniel Bensoussan, Agustín Barrajón Domenech, Raouia Ghanem, José Miguel Remón, Michel Marengo, Tristan Estaque, Alexis Pey, Stéphane Roberty, Carlo Nike Bianchi, Monica Montefalcone, Virginie Hartmann, Giovanni D’Anna, Jean‐Michel Cottalorda, Daniele Ventura, Georgina Torras Jorda, Vasilis Gerakaris, Ante Žuljević, Alice Oprandi, Fedra Dokoza, H. Molenaar, Walid Belgacem, Antonia Chiarore, Giovanni Chimienti, Manuel Fernández-Casado, Mélanie Cabral, Zrinka Jakl, Jelena Kurtović Mrčelić, Noëmie Michez, Patrizia Stipcich, Stéphane Jamme, Jorge Terrados, Jordi Boada, Yolanda Fernández‐Torquemada, Julia Máñez-Crespo, Aysu Güreşen, Edouard CHERE, Marija Despalatović, Gabriele Procaccini, Alice Mirasole, S. André, Periklis Kleitou, José Luis Sánchez‐Lizaso, Briac Monnier, Gianluca Mancini, Christine Pergent-Martinì, Sylvie Gobert, Núria Teixidó, Arturo Zenone, Valentina Lovat, Onur Karayalı, Arthur Lazennec, Éric Charbonnel, Javier Romero, Diego Moreno, Ivan Cvitković, Juan Eduardo Guillen Nieto, Noelia Hernández, George Constantinou, Inés Castejón, Daniele Grech, Balma Albalat-Oliver, Nuria Marbà, Jérémy Carlot, Manu Sant Felix, Bruno Belloni, Jaime Bernardeau-Esteller, Fiona Tomas, Emma Cebrian, Teresa Alcoverro, Luigi Piazzi, Charles-François Boudouresque, Jamila Ben Souissi, Antonio Scannavino, Muñoz Andres Izquierdo, Vincent Bardinal, Demetris Kletou, Dorian Guillemain, Thomas Schohn, Catalina A. Garcia-Escudero, Francisco Sobrado, Barış Akçalı, Bruno Ferrari, Juan Manuel Ruiz, Patrick Astruch, Pedro C. Navarro-Martinez
article en

Abstract

Abstract Following the unprecedented marine heatwaves of summer 2022, extensive flowering of the endemic seagrass Posidonia oceanica was witnessed across the western Mediterranean. To unravel the causes of this event, we conducted a pan-Mediterranean analysis across 442 sites spanning all Mediterranean ecoregions, with 76% exhibiting flowering. Flowering differed regionally, with both highest flowering prevalence (over 90%) and flowering intensity (up to 0.75) recorded in the Liguro-Provençal and Balearic Seas. We demonstrate that regions experiencing large summer sea surface temperature anomaly with high marine heatwave cumulative intensity displayed the highest flowering intensity. The probability of flowering was very likely when marine heatwave cumulative intensity exceeded ⁓120°C days. These findings suggest that marine heatwaves trigger flowering in P. oceanica and, given the high energetic cost of sexual reproduction, continued ocean warming may shift energy allocation toward flowering. This shift could profoundly affect the species’ reproductive strategies, posing major challenges and uncertainties for its long-term evolution.

Communications Earth & Environment
Centre National de la Recherche Scientifique (FR), University of Alicante (ES), WWF Colombia (CO), Université de Corse Pascal Paoli (FR), Ifremer (FR), University of Liège (BE), University of Sassari (IT), Université de Bretagne Occidentale (FR), Dokuz Eylül University (TR), Université Côte d'Azur (FR), Aix-Marseille Université (FR), Stazione Zoologica Anton Dohrn (IT), Sorbonne Université (FR), Ege University (TR), Instituto de Neurociencias (ES), Institute for Coastal Marine Environment (IT), Instituto Español de Oceanografía (ES), Mediterranean Institute for Advanced Studies (SI), Centre d'Estudis Avançats de Blanes (ES), Nature Environnement 17 (FR), Limassol General Hospital (CY), Hydrogen Fuel Cells and Electro-Mobility in European Regions (BE), French National Agency for Water and Aquatic Environments (FR), Centre Procédés, Energies Renouvelables et Systèmes Energétiques (FR), Mediterranean Institute for Advanced Studies (ES), Dokuz Eylül Üniversitesi Hastanesi (TR), Cepsa (Spain) (ES), Agence des Aires Marines Protégées (FR), Health Awareness (United States) (US), Consorzio per il Centro Interuniversitario di Biologia Marina ed Ecologia Applicata G. Bacci (IT), Institute for Biomedical Research and Innovation (IT), Institut National Agronomique de Tunisie (TN), Hellenic Centre for Marine Research (GR), Laboratory for Ocean Physics and Satellite Remote Sensing (FR), Institut de Biologia Evolutiva (ES), Fondazione Centro Marino Internazionale (IT), Conseil Régional du Languedoc-Roussillon (FR), Croatian Hydrographic Institute (HR), Observatoire Océanologique de Banyuls-sur-Mer (FR), Govern de les Illes Balears (ES), Agencia de Medio Ambiente y Agua de Andalucía (ES), Institut Océanographique (FR), Institut Méditerranéen d’Océanologie (FR), Institute of Oceanography and Fisheries (HR), Institut Universitaire Européen de la Mer (FR), Laboratoire d’Océanographie de Villefranche (FR), Grupo ACS (Spain) (ES), Institut de Recherche pour le Développement (FR), University of Bari Aldo Moro (IT), University of Montenegro (ME), Tunis El Manar University (TN), Istanbul University (TR), University of Naples Federico II (IT), University of Genoa (IT), Sapienza University of Rome (IT), University of Palermo (IT), University of Split (HR)
Agence Nationale de la Recherche, Fonds De La Recherche Scientifique - FNRS, Generalitat Valenciana
Life below water
Openalex Percentile: Top 6%
Marine and coastal plant biology
DOIOpen Access PDFOpenAlex
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