Black Sea chemistry and biodiversity is highly coupled with the lack of vertical currents, present in oceans or bigger seas. (Some ) effects are limited salinity in the top layers - and many ocean fish species cannot live in black sea - and limited space for life (under 50 meters there is no oxygen)
Can the jellyfish population (which is exploding now) change the stratification of water layers enough that the highly saline waters from bottom go up, and oxygen goes down, allowing a completely new ecosystem here?
If yes, what are the outcomes of such prospects? Besides the potentially catastrophic release of hydrogen sulphide form the bottom, can it be an improvement for the biodiversity here?