Filamentous algae are those thin fussy-looking, sometimes slimy, algae may find growing on hard substrates where they cover rocks and stones.
Some of them though grow on soft bottoms. Examples of these algae that specialize in growing on soft sediments are species of the genus Vaucheria. Vaucheria are yellow-green algae that grow long, tube formed and unbranched filaments that often can be seen growing straight up from the soft sea bottom like green spiky hair.
In some places the algae grow so abundantly that it looks like a green mat covering the whole sea floor. There gas can accumulate underneath the dense vegetation, forming gas pillars in the Vaucheria-mat, as seen in the video.
The video is taken during a free dive to a depth of about 2,5m, in a shallow bay where the bottom at the deepest part was covered by these algae.
Written by: Petra Pohjola, County Administrative Board of Norrbotten