Thick swathes of marine mucilage, also known as ‘sea snot’ because of its slimy texture, have started appearing around the Greek islands of Limnos and Agios Efstratios in the northeastern Aegean in recent weeks.
The phenomenon, caused by a nutrient overload in algae resulting from pollution and high temperatures, is being monitored by the Fisheries Research Institute on behalf of the Environment Ministry.
"It forms every so often but usually dissipates after a while. This is the first time in a decade we have seen so much," said Stavros Stathakis, vice president of the association of fishermen on Limnos.
He warned that the sludge is hampering fishing and also putting off tourists.
The "sea snot" first developed along the coast of Turkey, and bureaucrats warn the phenomenon could significantly impact the environment and is in danger of lasting all summer.
The mucilage blooms can also be seen developing along the coast of the adjoining Black seas during the spring and summer as water temperatures rise.