Fairy Rings in Baltic Sea explained after 5 mysterious years as biologists pin down the reason for the empty black circles beneath the seas shallow waters. The rings were first photographed in 2008 by tourists, and the explanations offered during the intervening years have been many and varied. Ranging from scorch marks from ancient alien landings to craters left by bombs dropped during World War II, the actual explanation is much less fantastic but still interesting. Rather than fairies, bombs, or aliens, the rings have turned out to be caused by plain old eel grass. The initial discovery left many unanswered questions as eel grass generally grows in meadows, but under observation it was found that the growth pattern is circular, from a central point. Eventually these circles join together to form the meadows usually seen.
Biologists responsible for identifying the actual cause of the Fairy Rings had a hard time pinning it down because it turns out that they take several years to form. Eel grass patches tend to be circular, with stronger grasses near the outer edge expanding outward into sprawling meadows as soil and nutrients allow. Grass that is growing in the middle of the ring is often longer with weaker root structures. Mud in the Baltic Sea contains sulphides that is toxic to the eel grass, but only enough to kill old or weak plants. As the inner plants become longer and longer, mud becomes entangled in the strands of grass, at which point the high sulfide content kills the inner portion of the patch, leaving the outer ring. With Fairy Rings in the Baltic Sea explained as a side effect of the growth patterns of eel grass, some are disappointed by the mundane origin of the imagination tickling rings but more are glad the threat of alien invasion has been lessened.
The striking black colouration in the centre of rings is due to the sulphide rich mud remaining in where the now dead grass held it. Still living grass around the edge of the circle grows longer over time, creating a fence that disrupts the currents responsible for sweeping the mud away. Sulphide levels climb due to the lack of iron and calcium carbonate leached from the chalky sea bed. While the mud is normally washed away by sea currents, the long grasses trap the mud as tree roots hold hillsides together. The rings are more likely to appear in areas where runoff from farms joins the Baltic Sea with minimum filtration, as the nitrogen found in most fertilizers causes an oxygen deprived environment, resulting in areas of high sulfide content. Now that the Fairy Rings in the Baltic Sea are explained, researchers point out the death of so much eel grass can have a negative impact on the underwater environment, as the grass is responsible for providing habitat for sea creature and filtering carbon dioxide from the water. Steps are being taken by Denmark officials to set up protective sanctions for the eel grass before the decline becomes too severe for the biome to support itself.
By Daniel O’Brien