Climate, Cnr: mass mortality for 50 Mediterranean species

Due to the heat waves between 2015 and 2019, the Posidonia oceanica and coralligenous meadows, two of the most emblematic habitats of the Mare Nostrum, are also at risk

Between 2015 and 2019 a series of heat waves hit all regions of the Mediterranean basin, causing events of mass mortality in 50 different marine species such as corals, sponges, macroalgae and even fish. According to an international research published in the journal Global Change Biology in which the Institute for Biological Resources and Marine Biotechnologies of the National Research Council (Cnr-Irbim) participated, these phenomena have affected thousands of kilometers of Mediterranean coasts, from the Alboran Sea. up to the eastern coasts, between the surface and 45 meters deep.

“Unfortunately, the results of the work show for the first time an acceleration of the ecological impacts associated with climate change, an unprecedented threat to the health and functioning of its ecosystems” explains Ernesto Azzurro, researcher at Cnr-Irbim. The scholar highlights that “the interaction between warming and the presence of new pathogens in marine environments with still little known effects is also worrying. From the exception to the norm, the climate crisis is severely affecting marine ecosystems around the world and the Mediterranean is a particularly important hotspot “.

The data provided by the study showed that there is a significant relationship between the duration of heat waves and the incidence of mortality events. “Mass mortality events in the Mediterranean are equivalent to bleaching events observed consecutively in the Great Barrier Reef as well, suggesting that these episodes are already the norm rather than the exception” underlines Carlo Cerrano, of the Marche Polytechnic University.

The Cnr reports that the research was carried out in collaboration with over 30 research groups from 11 countries, which made it possible to detect the incidence and severity of the phenomenon in every corner of the pelvis. The authors are working to strengthen scientific cooperation at all levels, in order to lift the drama of the current climate emergency, an emergency that must be considered today in all management and political choices.

“The marine heat waves recorded between 2015 and 2019 have been exceptional, compared to the available data covering the last 30 years, affecting more than 90% of the Mediterranean surface and reaching temperatures above 26ºC” explains Joaquim Garrabou, researcher of the Institut de Ciències del Mar (Icm-Csic) of Barcelona and coordinator of the study.

Among the species most affected are species that are fundamental for maintaining the functioning and biodiversity of coastal ecosystems such as, for example, Posidonia oceanica meadows or coralligenous, which represent two of the most emblematic habitats in the Mediterranean. “The research was carried out thanks to the support of the European projects H2020 Merces, H2020Futurmares, InterregMed Mpa-Engage and the Heatmed project (Rti2018-095346-B-485 I00).