A decade ago, healthy mats of lake balls spread over the bottom of Lake Mývatn in Iceland. Photo by Isamu Wakana.
Dr. Isamu Wakana prepares for a dive in Lake Mývatn in Iceland. Isamu is an expert on algae and has come a long way from Japan on his search for an extremely rare plant. As he descends to the bottom he is met by brown silt in every direction. This area was once covered by the world’s largest expanse of the peculiar yet beautiful lake balls. After swimming around for a few minutes he spots a protrusion from the sediment. He sticks his hand in the silt to recover the once lusciously green algae which has been buried alive. It is official, the lake balls of Mývatn have vanished.
You might be wondering what on earth a lake ball is? The species itself is called Aegagropila linnaei, and is in fact widespread in the Northern hemisphere. It is only this particular growth form, the lake balls, that are rare. The perfect spheres 10-15 cm across are found in just a few places: Lake Akan in Japan, Lake Svityaz in Ukraine and until last year they were also found in Lake Mývatn in Iceland.
The lake balls typically form 2-3 layer mats on the bottom of freshwater lakes. They are dependent on their regular dose of wind that fuels the waves, which gently turn the algae, keeping them clear of sediment and assuring that every ball gets their time in the sun. These can easily be regarded as one of the most peculiar plant societies in the world according to biologist Árni Einarsson, the director of the Nature Research Institute at Lake Mývatn.
The common name for the lake balls in Icelandic is Kúluskítur. Directly translated it means “round shit” which is supposedly what fishermen used to yell towards the bulky balls when they got caught in their nets in olden times. Biologists have since adopted the more gracious translation of “lake balls”. During those days Lake Mývatn was still one of the richest fishing lakes in Iceland but the entire ecosystem of the lake has been declining during the last few decades.
Árni Einarsson and Isamu Wakana believe that pollution is the culprit behind the poor state of the lake ball population. Mining operations for diatom shells started in the 1960´s resulting in further release of phosphorus and nitrogen into the already nutritious lake. The added nutrition was prime food for bacteria that burst into dense blooms, seriously challenging the visibility and penetration of light in the water column. The lake balls are highly dependent on sunrays reaching them at the bottom as energy for photosynthesis. As the algae mat deteriorated the sediment underneath became exposed and more easily stirred up by the wave action. On top of being starved of sunlight from above the balls have simultaneously been buried and suffocated by the sediment underneath. Mining operations ceased in 2004 but the ecosystem has continued to dwindle from the bottom up. The algae are an important substrate for several species of midge larvae and fish which in turn feed on the larvae. Fishing is now prohibited in the lake due to conservation reasons.
The lake balls seem to have a special meaning to their home countries. I first learned about these green balls in grade school. Whether it was their rarity, their strange shape or the rude name the lake balls always stuck in my mind. The same can be said about most Icelanders and the algae’s disappearance in the summer of 2013 was highly reported in local media. They are however far more famous in Japan. In the town Akan-ko-han at the brink of Lake Akan on the island of Hokkaido, lake balls or Marimo as the Japanese call them are held in very high regard. For over fifty years the Ainu people who are indigenous to the island have hosted the annual Marimo festival. The whole town gets dressed up in lake ball attire as the streets fill up with parades and dance shows in its honor. They are very proud of their natural treasure and have taken various measures to limit encroachment and pollution in the area to ensure the algae can continue to grow in peace.
When asked why he thinks people are so fond of the lake balls Dr. Isamu Wakana says: “Well, they are very cute and fluffy”. That coupled with their vulnerability and rarity might leave people with a feeling of responsibility as their guardian angels. “If somebody would have told me 20 years ago that the lake balls could disappear so suddenly I would not have believed them, it is a very sad story”, says Árni Einarsson. Discussion has started about possible solutions to mend the problem in Iceland. These include limiting further nutrient input to the lake that is again on the rise with increased traffic in the area as a result of Iceland’s recent tourist boom. If the nutrient balance could be restored the re-introduction of Lake balls in Mývatn might be attainable.
On my first dive in the restricted area I look at a lake ball grave on the now desolate bottom. I am in my infancy as a biologist and I am too late to witness the spectacular mats of algae balls that used to extend as far as the eye could see. It is a sad sight and like many Icelanders I hope to see a day when they return to Lake Mývatn. All the same I can’t help but wonder if this is only the first example of many I will witness in my career in life sciences, a career that is taking off in the shadow of a worldwide crash in biodiversity.