Succession and benthic community development in the sublittoral zone at the recent volcanic island, Surtsey, southern Iceland

Abstract

The island Surtsey was formed south of Iceland during an eruption that lasted form 1963 to 1967. The settlement of marine benthic organisms has been monitored at the island from the beginning. First with visits every year but after 1971 with some years between each visit. Since 1984 standard photographs have been shot of the hard substrate in the sublittoral to monitor species composition, cover and density. Data collected 1997 are presented here. In the shallower part of the sublittoral, algae are dominant. Below 15 m depth the cover and density of animals increases and at 30 m algae have disapeared. at the eastern coast the substrate seems more stable than elsewhere along the coast. Multivariate analysis shows two separate communities. a community with a mixture of Mytilus edulis, hydrozoans, Alaria esculenta and Polysiphonia stricta, primarily found where the substrate is unstable, and a community with Laminaria hyperborea, deep water red algae, sponges and Alcyonium digitatum on the more stable substrate.