A thick slimy layer of the organic matter, known as marine mucilage, has spread through the sea south of Istanbul, posing a threat to marine life and the fishing industry.

Harbors, shorelines and swathes of seawater have been blanketed by the viscous, greyish substance, some of which has also sunk below the waves, suffocating life on the seabed.

"Hopefully, together we will protect our Marmara within the framework of a disaster management plan," Environment and Urbanization Minister Murat Kurum said, speaking from a marine research vessel that has been taking samples of the slimy substance.

"We will take all the necessary steps within three years and realize the projects that will save not only the present but also the future together," Kurum said, adding that he would soon give details of the action plan.