Sea snot causing problems on Slovenian coast, swimming not advised

In recent days, many parts of the north Adriatic Sea have turned brown due to the sea snot, a quite rare phenomenon that is not directly harmful for the people, but can pose a threat to the sea life, said Tinkara Tinta, a researcher from the Maritime Biological Station in Piran.

The first records of sea saliva in the north Adriatic date back to 1729 and the last time it appeared here was in 2018, but this is the first time in about 20 years that it is so widespread. According to Tinta, the phenomenon was more frequent in the 1990s.

Sea snot can be a result of a number of factors that researchers are still struggling to comprehend. The gelatinous organic matter appears when phytoplankton, due to a combination of factors, starts to release large amounts of organic matter or complex sugars into the water, she explained.

This dissolved organic matter forms slimy aggregates at the sea surface or in deeper layers of water. "Along the coast, where the sea is shallow, it can be quickly blown away by a storm, but deeper, it can take a while for it to mix with the water and dissolve, up to one or two months. Physically removing the slime from the seabed is almost impossible, but on the water surface people sometimes remove it with nets," Tinta said.

Although the organic matter does not pose a direct threat to people's health, experts advice people to stay away. The National Biology Institute and the National Institute of Public Health warned today against swimming in the waters affected by sea snot, because pollutants get caught up in the snot.

Rain water and melting snow wash different substances from land to the sea, including microorganisms that can cause disease, and all this gets caught up in the sea snot, they warn.

Sometimes particles such as organisms' skeletons and sediment particles get caught up in the sea snot as well, which can cause skin irritation.

But while this may be unpleasant, sea snot can pose a serious threat to the organisms living on the sea bed and the slow moving animals that are unable to get away from the snot, which can cause them to suffocate.

It is assumed that marine mucilage occurs because of nutrients abundance. "This year, heavy rainfall caused rivers to swell and they brought these nutrients to the sea," said Tinta. Limited activity of bacteria that break down complex sugars and proteins in the sea may also be to blame. "These bacteria need nutrients such as phosphorus to grow and function, and if there is not enough of these, it is difficult for the bacteria to perform their role as decomposers," she explained.

In summer warmer water raises to the surface and cooler remains down, which prevents the mixing of essential nutrients for these bacteria, she said, adding that sea snot occurrence was an extremely complex phenomenon, which will require quite a lot more research work.