Although we generally focus on local freshwater issues here at the Aquatic Ecology Lab, sometimes it’s interesting to zoom out, and see what’s happening in other parts of the world. Studying ecosystems both near and far can provide interesting insight into global ecological trends, which is especially important in the face of climate change (see our most recent post by Amelia).
Today, we’ll travel to Iceland, which has always been a place of mystery for many reasons… vikings, elves, lake monsters…But folklore aside, the unusual geothermal landscape, paired with a surprisingly mild climate for an arctic-circle-bound island, also makes for some mysterious organisms.
In Lake Mývatn, a rare form of ball-like algae, Aegagropila linnaei, colonizes the lake floor – or at least it used to. Since their discovery by scientists in 1977, the algae balls have been disappearing rapidly. Aside from Iceland, the only other place these large algae balls seem to form such peculiar colonies are in Lake Akan, Japan.
The reason A. linnaei ball colonies are so rare, is because they require Goldilocks conditions; lake clarity, wave action, and wind patterns must be just right. In addition, there must be the right balance of invertebrates on the lake floor. The algae balls, which usually form around small pebbles, rely on a symbiotic relationship with oligochaetes, or aquatic worms.
Although the disappearance of these algae balls may be attributed to factors like increasing storm frequency, perhaps due to climatic changes, it seems as though the real reason for their loss is due to rising levels of nutrients, or eutrophication. With more nutrients comes more productivity (algae, for example), especially in cold likes like Mývatn. With more productivity also comes more organic matter, which falls to the bottom of the lake to form a blanket over the algae balls, squelching their access to sunlight.
Although we may think of far-away places like Iceland to be untouched by human activity, this is just another reminder of how our actions can have global effects. Eutrophication is not only a problem that plagues dammed rivers and lakes and the Gulf of Mexico, but also cold, seemingly pristine lakes in far-away places like Iceland. Stories like that of the A. linnaei algae balls should reinforce the need to continue research that investigates the fate of our freshwater ecosystems in the face anthropogenic change.
To learn more, check out this memoir to algae balls.