An international team of researchers led by the University of Barcelona, in collaboration with the University of the Aegean and the Hellenic Centre for Marine Research, has uncovered evidence showing that a massive outflow of low-salinity water from the Black Sea into the Aegean Sea during the Early Holocene (approximately 11,000-6,000 years ago) played a much more important role in shaping the Eastern Mediterranean than previously thought.
The study, published in the Nature Portfolio journal Communications Earth & Environment , demonstrates that freshwater exported from the Black Sea enhanced surface-water stratification in the Aegean Sea, suppressing the formation of deep waters and contributing to the development of the so-called Sapropel 1, a widespread organic-rich sediment layer deposited across the Eastern Mediterranean during the Early Holocene.
The findings extend beyond the Eastern Mediterranean's past. By demonstrating how large freshwater inputs can disrupt deep-water formation and reorganize marine circulation, the study offers valuable insights into the links between climate, hydrology and ocean circulation during warm periods, helping scientists better understand the potential consequences of future climate change.
The Black Sea: More important than previously thought
For decades, scientists have largely attributed the formation of Sapropel 1 to increased freshwater input from North African rivers and enhanced precipitation over the northern Mediterranean region. These processes were thought to reduce deep-water formation and promote conditions favourable for the accumulation of organic-rich sediments on the seafloor. The new findings challenge this long-standing view by identifying the Black Sea as a major and previously underestimated driver of these environmental changes.
