For a decade, marine biologist Nur Eda Topcu has fought to preserve delicate corals off the Istanbul coastline, which environmentalists say are threatened by the dumping of industrial waste, fuel and sewage.
Now she fears a new threat may hasten the end of the Sea of Marmara’s coral reefs. A gelatinous substance colloquially known as sea snot has in recent months choked aquatic life, blighted fishing and repelled swimmers.
Long brown streaks of the marine mucilage were still visible across the Marmara in late July, while the gooey foam sank below the surface settling on the rare corals. Scientists warn that the sea, whose mix of Mediterranean and Black Sea currents foster coral usually found at far deeper depths, itself is at risk.
“The death knells are ringing for the Marmara,” said Topcu after surfacing from a recent dive to clean the slime that coated normally fuchsia-hued corals off an Istanbul archipelago. “We can’t stop the mucilage. It’s smothering the gorgonians [and] infecting them with harmful bacteria.” She fears most of Marmara’s soft, red Paramuricea clavata, listed as a vulnerable species of coral, will perish this year.
Factories have nearly doubled the deluge of wastewater they discharge into Turkey’s seas in recent years, according to official statistics. The 50,000 tankers that sail through the Marmara each year illegally dump waste and fuel, according to one municipal monitor. Almost two-thirds of the nation’s industry, including an oil refinery, carmakers, chemical plants and power stations, is concentrated in the region.
Most wastewater from Istanbul, Turkey’s largest city, is only treated to remove solids, then pumped to the bottom of the sea. “We use it as our cesspool,” said Levent Artuz, a hydrobiologist at the Marmara Environmental Monitoring Project and author of a new book A Recent History of the Polluting of the Sea of Marmara.
The situation was not helped by the fact that sea temperatures had climbed by an average two degrees Celsius in the Marmara since the start of this century as pollution trapped heat, he said. A state project that diverted the Ergene River, one of Europe’s most toxic waterways, to the Marmara last year was “the tipping point”.
“The essential problem isn’t mucilage. That’s just a link in the chain of decades of degradation,” Artuz said. “We have zero chance of recovering the Sea of Marmara as it was. What we have to do now is figure out how to prevent the Marmara from harming us.”
In recent years, marine life has died in mass mortality events, and there have been infestations of jellyfish and algal blooms such as red tides and mucilage.
But scientists and fishermen say the current flare-up is unprecedented. Phytoplankton is flourishing because of nutrient-rich sewage and fertiliser from agricultural runoff while overfishing has wiped out populations of small fish and crustaceans that would consume the algae.
Gone are the mackerel, tuna, swordfish and other seafood that Istanbul was known for. This year’s haul was down 90 per cent from 2020 as mucilage clogged and dragged off nets, said Erdogan Kartal, the head of Istanbul’s fishing co-operative. “Even if we could supply fish markets, customers aren’t buying out of disgust.”
Recep Tayyip Erdogan, Turkey’s president, has vowed to crack down on polluters and “save our seas from this scourge of mucilage”. Thousands of cubic metres of the sea snot had been vacuumed up, the country’s environment minister said. In early July, he pronounced the Marmara “cleaner and bluer” than before.
Turkey is the only G20 country that has not ratified the Paris accords on climate change, and grassroots movements to protect the environment are often viewed as provocateurs by the government.
Authorities have refused to register a new Green party eager to fight climate change. Scientists also say that a planned shipping canal from the Black Sea to the Marmara could deplete oxygen in the Marmara and promote hydrogen sulphur gas that would envelop Istanbul with the stench of rotten eggs. Erdogan’s transportation minister argues that the cleaner water coming through from the Black Sea would improve the quality of the Marmara.
Along the way, there have been successes for Topcu and members of Istanbul’s Marine Life Conservation Society (MLCS). They secured protected status for the tiny outcrop of Neandros this April, stopping boats from dropping anchors or trawling for fish near its corals. They spent two summers transplanting fan-like yellow sea whips to Neandros after a nearby colony of the golden Eunicella cavolini was buried in debris from a government construction project.
“We carried them like a heart or kidney for transplant, keeping them in cold water and in the dark to prevent shock,” said Serco Eskiyan of the MLCS. It took more than 100 dives to harvest and replant 300 corals 30 metres down.
But Eskiyan, who has dived the waters off the islands since the 1970s and knows the area “like the rooms in my house”, was unable to locate the transplants in July, blinded by the sea snot that reduced visibility to a metre or two. “It looks like a different planet,” said Topcu.
A generation ago, the Marmara’s rich fauna included seahorses, poisonous scorpionfish and great white sharks, now all gone, though Eskiyan still occasionally confronts a rare angular roughshark when he hunts for “ghost nets” abandoned by industrial fishing boats that choke the corals. The MLCS has collected 32,000 square metres of the meshing since 2015.
“I have faith in the sea’s ability to renew itself from the damage people do. But now I question how much longer it can fight back,” Topcu said.