The Sublittoral Zone

In the first years after Surtsey’s formation, only a few species of benthic algae and animals could be found. The species were distributed sparsely, sometimes at a depth that was not natural to them compared to other coastal areas of Iceland. The first organisms to be discovered on the hard sea floor around Surtsey were colonial diatoms and the the brown alge, bladderlock (Alaria esculenta), Among animals found here at this time were the saddle oyster (Heteranomia squamala), wrinkled rock borer (Hiatella arctica), and common mussel (Mytilus edulis). Crustacean species – e.g. the acorn barnacle and Verruca stroemia – were also found, as well as one shrimp species and the crab species Arctic lyre crab (Hyas coarctatus). Since then the number of species of algae and benthic animals has grown, and benthic communities have developed.

At present there are two different communities on the sea floor around Surtsey. First, there is a community in shallow waters, at a depth of 0-15 m, consisting of bladderlock (Alaria esculenta), forest kelp (Laminaria hyperborea), mermaids hair (Desmarestia aculeata), Polysiphonia stricta and other species. The other community is found in deeper waters (20-30 m depth), where red algae species are dominant, primarily the red algae Phycodrys rubens, Lomentaria orcadensis, and purple laver . The most characteristic animal in the deep community is the soft coral species dead man’s fingers (Alcyonium digitatum).