A new study paves the way to understanding biotic recovery after an ecological crisis in the Mediterranean that occurred about 5.5 million years ago. An international team led by Konstantina Agiadi from the University of Vienna (Austria) has now managed to quantify the impact that salinization has had on Mediterranean marine biodiversity: only 11% of endemic species survived the crisis, and biodiversity did not recover for at least 1.7 million years.
The study was published in magazine Science.
Lithospheric movements throughout Earth’s history have repeatedly resulted in the isolation of regional seas from the planetary ocean and massive accumulations of salt. Salt giants, having thousands of cubic kilometers, have been discovered by geologists in Europe, Australia, Siberia, the Middle East and other places. These salt deposits are valuable natural resources and have been exploited from ancient times to the present day in mines around the world (for example, the Hallstatt mine in Austria or the Khewra salt mine in Pakistan).
The Mediterranean Salt Giant is a kilometer thick layer of salt under the Mediterranean Sea that was discovered in the early 1970s. It was formed about 5.5 million years ago due to disconnection from the Atlantic Ocean during the Great Depression. Messinian salinity
Mediterranean marine biodiversity during the Messinian crisis was quantified
In the study, an international team of researchers, composed of 29 scientists from 25 institutes in Europe and led by Konstantina Agiadi of the University of Vienna, has now succeeded in quantifying Mediterranean marine biodiversity following the Messinian crisis and biotic recovery later.
After several decades of painstaking research on fossils dating from 12 to 3.6 million years ago, found on land in peri-Mediterranean countries and in deep-sea sediment cores, the team discovered that nearly 67% of marine species in the Mediterranean Sea after the crisis were different from those before the crisis.
Only 86 of the 779 endemic species (which lived exclusively in the Mediterranean before the crisis) survived the massive change in living conditions after the separation from the Atlantic. The changing configuration of the straits, which led to the formation of the salt giant, caused abrupt fluctuations in salinity and temperature, but also changed the migration paths of marine organisms, the flow of larvae and plankton, and disrupted central ecosystem processes, writes Eurek Alert.
Because of these changes, much of the inhabitants of the Mediterranean at that time, such as tropical reef-building corals, disappeared. After the reconnection to the Atlantic and the invasion of new species, such as white sharks and oceanic dolphins, the Mediterranean marine biodiversity showed a new pattern, with the number of species decreasing from west to east, as is still the case today.
Analysis of a major ecological crisis
Because peripheral seas, such as the Mediterranean, are important hotspots of biodiversity, it was highly likely that the formation of salt giants throughout geologic history had a significant impact, but this had not been quantified until now.
“Our study now provides the first statistical analysis of such a major ecological crisis,” explains Konstantina Agiadi, from the Department of Geology. In addition, the study also quantifies for the first time the time frame required to recover from a marine ecological crisis, which is much longer than expected: “Biodiversity, in terms of the number of species, only recovered after more than 1.7 millions of years”, says the georesearcher.
The methods used in the study also provide a model connecting plate tectonics, the birth and death of oceans, salt and marine life that could be applied to other regions of the world.
“The results open up a series of interesting new questions,” says Daniel García-Castellanos of Geosciences Barcelona (CSIC), lead author of this study.
“How and where did 11% of species survive Mediterranean salinization? How did older and larger salt formations change ecosystems and the Earth system?” he asks. These questions are also to be explored further in the new Cost Action network ‘SaltAges’, starting in October, where researchers are invited to explore the social, biological and climate impacts of the Salt Ages.
We recommend you also read:
For the first time, alarming levels of fiberglass have been found in the food chain
The last 12 months marked the warmest period ever recorded on Earth
Rare phenomenon! The reason the world’s driest desert turned purple
Will climate change cause more earthquakes?
Source: www.descopera.ro
