Lake Mývatn is located in Iceland and, along with Lake Akan in Japan and Lake Svityaz in Ukraine, until recently it was one of the very few places on Earth where lake balls could be found. What are lake balls, you ask? They’re fuzzy, green balls about 10 to 15 centimeters in diameter – and often found at the bottom of these freshwater lakes.
Lake balls are really just algae, a species named Aegagropila linnaei. The species is extremely common in the northern hemisphere, but their shape is not.
These unique formations of algae are turned by the waves, which roll the balls around and allow the sun to warm every side. About a decade ago, the lake balls in Lake Mývatn were two to three layers thick on the lake bottom. Today, they’re gone.
Dr. Isamu Wakana is an expert on algae, and he has journeyed to Iceland to understand the lake balls’ disappearance. Along with Árni Einarsson, the director of the Nature Research Institute at Lake Mývatn, Wakana believes that pollution is the problem.
In the 1960s, mining operations in the area released phosphorous and nitrogen into the lake. This led to a bonanza for the lake’s bacteria, which thrived on the extra nutrition, swarming so densely that they blocked the sunlight that shined down through the water column. As the algae received less sunlight, they began to die, exposing more of the lake bottom’s loose sediment. The wind and the waves that once rolled the balls into their shape then began to work against the balls, stirring the loose sediment and covering the remaining algae, choking them off from sunlight altogether.
The loss of the lake balls amounts to more than just aesthetics. Without the algae in the lake’s ecosystem, several species of midge larvae have been deprived of a prime food source. This, in turn, deprives fish of their own food source. And this, ultimately, results in fewer fish in what was once one of the richest fishing lakes in the country.
Wakana and Einarsson are currently working together to bring the lake balls back to Mývatn. Fishing has been prohibited, and they suggest limiting further nutrient input until the bacterial balance is restored.