What is Turkey's 'sea snot' outbreak and how does it threaten marine life?

New underwater video shot by documentary filmmaker Tahsin Ceylan showed a slimy 'sea snot' expanding in Sea of Marmara as Turkish government launched a disaster management programme meant to clean up the outbreak. Video shot by Ceylan, shortly before cleaning efforts has begun, showed layers of 'sea snot' floating on the surface of water and covering marine plants.