Black Sea

Black Sea

The Black Sea has lost more than a third of its habitable volume

With rivers providing an abundant supply of fresh water, the upper layers of the Black Sea are less dense than its saltier lower layers. A permanent boundary between the two prevents any vertical mixing. The oxygen, derived from the atmosphere and photosynthesis, remains restricted to these surface waters. However, this precious gas is essential to the development of the majority of living species. Recent research has shown that this oxic boundary shoaled from 140 to 90 metres between 1955 and 2015. A compression of almost 40% of the habitable space in the Black Sea, directly linked to its eutrophication and global warming. This phenomenon could be accompanied by major ecological and economic consequences. Ref. Source 5x.