From Tuscany to Campania, hundreds of thousands of unidentified plastic discs have washed up on Italy's western coast in recent weeks.
The white discs began turning up in southern Italy about a month ago, according to Clean Sea Life, a group that campaigns to clean up Italy's beaches, which said it received the first report from Paestum beach on February 21st.
Since then hundreds of thousands more have been spotted all along the Tyrrhenian coast, says the group, which has been mapping the sightings and alerting regional authorities.
Some of its members picked up 800 of the discs in one hour on a single beach, it said.
It is not known where the discs came from or how so many of them ended up in the sea, but Clean Sea Life suspects that they are parts for a water purification plant that were either washed out during heavy rains or somehow fell into the ocean while they were being delivered.
Oceanographers are studying the log of sightings to try to work out where the spill most likely took place. They believe it was somewhere in the Gulf of Naples and that currents later swept the discs north.
Update on the big spill of disks, likely used in waste water treatment aka #hooksetdisks washing up by the 1000s in central Italy. @CleanSeaLIFE coordinating w local, regional auth, coast guard and oceanographers to backtrack source &cleanup #marinelitter #marinedebris #6IMDC pic.twitter.com/UGJmc8JjEr— CleanSeaLIFE (@CleanSeaLIFE) March 17, 2018
The group is urging members of the public to let them know if they spot the discs and, even more importantly, to pick them up.
"If it had been done right away, we wouldn't find ourselves with hundreds of sightings of discs all over the Tyrrhenian a month later," Clean Sea Life said. "If we don't pick them up now, they'll continue to pollute our sea forever, breaking up bit by bit into smaller and smaller pieces without ever disappearing completely."
Studies suggest that more than 90 percent of litter floating in the Mediterranean or on its deep sea floor is plastic, according to Greenpeace. The Med has an especially high concentration of microplastics – fragments less than 5mm long – which have been measured at 1.2 million per square kilometre, one of the highest rates in the world.
Worse than dirtying beaches, such pollution can have a devastating effect on marine creatures, which become tangled in debris or mistakenly ingest it. And once it's in the food chain, we're probably eating it too.