The deep vault: a temporary refuge for temperate gorgonian forests facing marine heat waves

Climate change poses a significant threat to coastal areas, marked by the increasing intensity and frequency of marine heat waves observed in various ecosystems around the world. Over the last 25 years, a vast number of Mediterranean populations of the red gorgonian Paramuricea clavata have been impacted by marine heatwaves. The last mass mortality occurred during the summer of 2022 in the Western Mediterranean Sea, affecting mostly shallow populations (down to 30 m depth). Here we provide an assessment of the health status of mesophotic P. clavata populations down to 90 m depth to investigate a depth refuge hypothesis. Results show that the impact of marine heat waves decreases with depth, with a significant drop in mortality below 40 m depth. These observations support the hypothesis of a depth refuge from marine heat waves that may allow, at least temporarily, the maintenance of P. clavata in the Western Mediterranean Sea. The present study strongly advocates for further investigations and monitoring of the mesophotic zone to chart potential areas that could serve as deep refuge for gorgonians.


Mass mortality events, sea-fan, Mediterranean Sea, mesophotic, deep refuge, extreme events, temperate corals, habitat-forming species, climate change, octocorals

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Bramanti LORENZO, Manea ELISABETTA, Giordano BRUNA, Estaque TRISTAN, Bianchimani OLIVIER, Richaume JUSTINE, Mérigot Bastien, Schull Quentin, Sartoretto Stephane, Garrabou JOAQUIM GARRABOU, Guizien KATELL (2023). The deep vault: a temporary refuge for temperate gorgonian forests facing marine heat waves. Mediterranean Marine Science. 24 (3). 601-609.,

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