An international study that sheds light on the ecological crisis in the Mediterranean 5.5 million years ago published in the journal “Science”
A new study just published in the journal Science sheds light on the impacts of the ecological crisis that occurred in the Mediterranean Sea some 5.5 million years ago. An international team involving 25 institutes across Europe, including Unimore with Professor Francesca Bosellini, a palaeontologist and professor in the Department of Chemical and Geological Sciences, was able to quantify the impact of Mediterranean salinization on marine biota: only 11 percent of endemic species survived the crisis and biodiversity did not recover for at least another 1.7 million years.
Lithospheric movements throughout Earth's history have repeatedly led to the isolation of regional seas from world oceans and massive salt accumulations. These are true “salt giants” of thousands of cubic kilometres found by geologists in Europe, Australia, Siberia, the Middle East and elsewhere.
After several decades of research, the team found that nearly 67 percent of marine species in the Mediterranean Sea after the crisis were different from those pre-crisis. Only 86 of the 779 endemic species (which before the crisis lived exclusively in the Mediterranean) survived the enormous change in living conditions after the separation of the Mediterranean from the Atlantic.
The change in the configuration of the present Strait of Gibraltar, which led to the formation of the salt giant itself, caused abrupt fluctuations in salinity and temperature, but also changed the migratory pathways of marine organisms, the flow of larvae and plankton, and disrupted the central processes of the ecosystem. Because of these changes, most of the Mediterranean inhabitants of that time, such as tropical reef-building corals, became extinct.
After the reconnection with the Atlantic and the invasion of new species, such as great white sharks and oceanic dolphins, the marine biodiversity of the Mediterranean presented a new pattern, with the number of species decreasing from west to east, as is the case today.
“The 'salt giant,' as a kilometre-thick salt layer located under the Mediterranean Sea has been called, and the biotic and ecological crisis event associated with it, have attracted the attention of geologists and palaeontologists from all over the world since the 1970s” commented Unimore Professor Francesca Bosellini. For the first time, a team of 29 scientists from 25 research centres was able to quantify the loss of biodiversity in the Mediterranean Sea due to this crisis and the subsequent recovery. We studied fossils from that period and found that nearly 67 percent of marine species in the Mediterranean after the crisis were different from those before. Only 86 of the 779 endemic species (which lived exclusively in the Mediterranean before the crisis) survived the enormous change in living conditions after the separation from the Atlantic. The impact of the crisis has been enormous: in addition to the disappearance of many species, the migratory routes of marine organisms, the flow of larvae and plankton have radically changed, and tropical coral reefs, which have been studied for years at Unimore's Department of Chemical and Geological Sciences, have definitively disappeared from the Mediterranean. Recovery from this crisis has been slow, slower than one might have expected. Biodiversity crises are a highly topical issue, and understanding the causes, mechanisms and recovery times of past ones gives us the only way to make long-term predictions about the future of today's ecosystems.
Categorie: Notizie_eng
Articolo pubblicato da: Ufficio Stampa Unimore - ufficiostampa@unimore.it