A recent study has shed light on the impact of an ecological crisis, known as the Messinian Salinity Crisis, on marine biodiversity in the Mediterranean Sea around 5.5 million years ago. Led by Konstantina Agiadi from the University of Vienna, an international team of researchers found that only 11% of endemic species survived the crisis, leading to a significant loss in biodiversity that took at least 1.7 million years to recover. The study, published in the journal Science, quantifies the effects of the crisis and subsequent biotic recovery, providing insight into the long-term consequences of ecological disturbances.
Throughout Earth’s history, lithospheric movements have caused the isolation of regional seas from the world ocean, resulting in the formation of massive salt accumulations. These salt giants, found in various locations around the globe, have been valuable natural resources that have been exploited for centuries. The Mediterranean salt giant, a kilometer-thick layer of salt beneath the Mediterranean Sea, formed approximately 5.5 million years ago during the Messinian Salinity Crisis when the Mediterranean was disconnected from the Atlantic. This discovery has provided geologists with valuable insights into the geological history of the region.
The study conducted by Agiadi and her team involved analyzing fossils dated from 12 to 3.6 million years found in peri-Mediterranean countries and deep-sea sediment cores to assess the impact of the Messinian crisis on marine biodiversity. They found that nearly two-thirds of marine species in the Mediterranean changed following the crisis, with only a small fraction of endemic species surviving the dramatic environmental changes. The disruption in migration pathways, flow of larvae and plankton, and central ecosystem processes led to the extinction of many species, including tropical reef-building corals.
Despite the reconnection to the Atlantic and the invasion of new species, such as the Great White shark and oceanic dolphins, the recovery of Mediterranean marine biodiversity took longer than expected. The study revealed that it took over 1.7 million years for the number of species to recover to pre-crisis levels. This finding challenges previous assumptions about the timescales of recovery after an ecological crisis and highlights the importance of understanding the long-term impacts of such events on marine ecosystems.
The research not only provides a statistical analysis of a major ecological crisis but also offers a model for understanding the relationship between plate tectonics, oceanic changes, salt formation, and marine life. This model could be applied to other regions of the world to assess the impact of similar events on marine biodiversity. The results of the study have raised new questions about how species survived the salinization of the Mediterranean and how previous salt giants may have altered ecosystems and the Earth system.
Moving forward, researchers are encouraged to explore the social, biological, and climatic impacts of salt ages, as well as investigate the broader implications of ecological crises on marine biodiversity. The study has set the stage for further research into the long-term effects of environmental disturbances on ecosystems and the potential solutions for mitigating these impacts in the future. By gaining a better understanding of past ecological crises, scientists can better inform conservation efforts and management strategies for protecting marine biodiversity in the face of ongoing environmental changes.
