Changing Planet

Icelanders Grieve for the Peculiar Lake Balls


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.

A rescued lake ball from Lake Mývatn, Iceland.
A rescued lake ball awaits further examination at the Nature Research Institute of Mývatn, Iceland. Photo by Jónína Ólafsdóttir.

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.

Lake Mývatn, Iceland.
The shallow freshwater lake Mývatn is one of very few places worldwide where the peculiar lake balls have been found. As of 2013 the algae has vanished from the area. Photo by Jónína Ólafsdóttir.

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.

Isamu Wakana and Árni Einarsson with a lake ball.
Isamu Wakana and Árni Einarsson discuss methods for possible re-introduction of lake balls. Photo by Jónína Ólafsdóttir.

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.

Ainu Marimo Lake ball festival in Japan.
The Ainu people, which are indigenous to the island of Hokkaido in Japan, live by the shores of Lake Akan. Every year they celebrate the annual Marimo festival in honor of the lake balls. Photo by Isamu Wakana.

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.

A buried lake ball at the bottom of Lake Mývatn.
A lake ball that has been buried alive protrudes from the sediment at the bottom of Lake Mývatn. Photo by Jónína Ólafsdóttir.

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.


Jónína Herdís Ólafsdóttir is a biologist and a National geographic grantee. She is extremely passionate for the natural world, science and adventure. Jónína was introduced to scuba diving early on and became fascinated with how the skill could take her to pristine, extreme, and even “other worldly” environments. Her love for the underwater realm shapes her research interests and she is currently focusing on mapping biodiversity in groundwater-filled fissures in Iceland.
  • Ima Ryma

    My Grampa was a fisherman.
    He’d tell of Lake Myvatn in
    Iceland where plain green algae can
    Grow in big balls in nature’s spin
    By freshwater waves of each ball,
    To keep it free of sediment,
    And assure the sun hitting all.
    This ecosystem – rare event.
    Fish nets often pulled up a heap,
    Curse after curse was hurled upon,
    Yelling the catch was of round “bleep.”
    “Progress” pollution – all balls gone.

    Lake life will not be as before.
    There is no fishing anymore.

  • Zeineb Messaoudi

    Tellement désolée de voir l’impact néfaste de l’homme sur terre dans la mère et même dans les régions protégées par leurs climats. Vraiment rien ne survit au contact de la machine de ” l’évolution” de l’homme

  • ted schettler

    Thanks for this article. Quite coincidentally, I just happened to find this in Henry David Thoreau’s essay “The Ponds” (

    “Flint’s, or Sandy Pond, in Lincoln, our greatest lake and inland sea, lies about a mile east of Walden. It is much larger, being said to contain one hundred and ninety-seven acres, and is more fertile in fish; but it is comparatively shallow, and not remarkably pure. A walk through the woods thither was often my recreation. It was worth the while, if only to feel the wind blow on your cheek freely, and see the waves run, and remember the life of mariners. I went a- chestnutting there in the fall, on windy days, when the nuts were dropping into the water and were washed to my feet; and one day, as I crept along its sedgy shore, the fresh spray blowing in my face, I came upon the mouldering wreck of a boat, the sides gone, and hardly more than the impression of its flat bottom left amid the rushes; yet its model was sharply defined, as if it were a large decayed pad, with its veins. It was as impressive a wreck as one could imagine on the seashore, and had as good a moral. It is by this time mere vegetable mould and undistinguishable pond shore, through which rushes and flags have pushed up. I used to admire the ripple marks on the sandy bottom, at the north end of this pond, made firm and hard to the feet of the wader by the pressure of the water, and the rushes which grew in Indian file, in waving lines, corresponding to these marks, rank behind rank, as if the waves had planted them. There also I have found, in considerable quantities, curious balls, composed apparently of fine grass or roots, of pipewort perhaps, from half an inch to four inches in diameter, and perfectly spherical. These wash back and forth in shallow water on a sandy bottom, and are sometimes cast on the shore. They are either solid grass, or have a little sand in the middle. At first you would say that they were formed by the action of the waves, like a pebble; yet the smallest are made of equally coarse materials, half an inch long, and they are produced only at one season of the year. Moreover, the waves, I suspect, do not so much construct as wear down a material which has already acquired consistency. They preserve their form when dry for an indefinite period.”

  • Marge Poston

    So sad that man’s greed and “could care less” attitude has brought us to the brink of anialation. The jeopardy of our (home) planet and the and extection of mankind because of our insect(bees) decline. We are doomed unless a whole lot of people wake-up!!!!!

  • Karla Turlich Arnold

    Very pretty.

  • Karla Turlich Arnold

    Very green.

  • Karla Turlich Arnold

    Sad situation.

  • Elfa Dröfn Ingólfsdóttir

    Is’int Kúluskítur also found in Apavatn, Iceland. At least I and my husband found it there like 20 years ago. It was the same sice like an olive

  • mary de toma

    People around me always wonder why i am so interested in this kind of news and why i post them on my Facebook page… what i wonder is why don’t they? Is it only me who care about the slow but continue destruction of our planet? There’s a reason why these plants exist…

  • Roxanne Scoville

    “Don’t they have these in the spring at Sun Pass State Forest, Fort Klamath, Oregon, USA? Smaller of course!” “In a spring in the valley near Crater Lake NP.” (As reported to me by Forestry experts.)

  • Sophie shokemi

    Interesting : as a geographer and researcher , i would like to know more about Lake Balls .

  • Carl Sagan

    It is normal, in fact quite normal because of human kind “art of destroying and eating everything” even air, water and ground. Make the difference you (you all and me together) There are thousands of things (Little things) tha will créate a very big change

  • Tracie Freeman

    Hopefully they will return!

  • Sarah K Bacowsky

    I agree. This is only one of many.

  • Roxanne Scoville

    Spring Creek, Collier State Park and spring at Sun Pass State Park, Klamath Falls, Oregon, USA have “Mare’s Eggs” as they label them. My friends who work in Forestry tell me that they are about golf ball size. Question: When did they disappear and is there any relationship between the silt deposited in the lake and any of the volcanic activity in Iceland? Just wondering. This is my second time commenting. Thanks for all you do!

  • Melissa Stoner

    We have these in some high mountain lakes in Idaho. Not as fluffy and mossy though. More like a thick gelatinous orb the texture of a seaweed stalk. Have long wondered what they were.

  • Diane Doherty

    There has appeared on our local beach (north west facing)……ball shaped ,what appears to be dead grass,very tightly packed in to a tight ball……we have never seen the likes of these before on our beach,and its only on this one particular beach.

  • Jónína Ólafsdóttir

    I am sorry for my very late reply. It is right that small growth forms of lake balls are known from a few lakes is Iceland as well as from some lakes in the US and Scotland for example. Other algae species can on occasion be confused with the lake balls. For anyone interested in reading more about the algae I highly recommend a recently published report: The Lake Balls of Mývatn; In Memoriam by Árni Einarsson.

    Best regards 🙂

  • Annette

    I have come across these balls in the Columbia Gorge in the town of The Dalles Oregon one that was not little by any means this one was 2 foot by 2 foot , its very large in size , but how did it get here .

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