A deluge of sea snot, like the one in Turkey, occurs only under certain conditions. First, waters need to be warm and stagnant. This is becoming more common as climate change causes sea temperatures around the world to rise. Second, the waters must contain high levels of nutrients that fuel the growth of microbes. In the case of the Marmara Sea, nutrients probably came from sewage plants dumping waste into the water. In this environment, microscopic organisms called diatoms flourish. As they multiply, they expel sticky mucus. Fish poop and bits of dead plants and animals can get stuck in the gunk, making matters worse.
Sea snot is deadly for marine life. It coats the seafloor, smothering everything that lives there. “Worms, corals, fish, and more will die,” says Alldredge. Luckily, large sea snot events happen only every few years. Usually, the mucus produced by diatoms forms small blobs that sink slowly to the seafloor, where hungry creatures gobble up the goo. “It’s gross,” says Alldredge, “but it’s the main food source for many deep-sea organisms.”