Coastal habitat types

The coast (littoral shores) is defined as marine habitats where saline (>30 S) or brackish (0,5–30 S) water washes over the ground at high tide or in the surf. On sheltered shorelines, littoral shores are mainly delineated by tidemarks. Along exposed shorelines, where ocean spray or splash reach varying distances in windy weather, the upper limit of the littoral shore can be much farther inland than the high-tide mark (supralittoral zone), and the lower limit may likewise be somewhat below the low-tide mark. The coast also includes saline and brackish pools above the spring high tide limit, together with the littoral fringe, where sea tar lichen (Verrucaria maura) grows. The width or extent of the littoral shore at any given location is determined by the difference in height between high and low tides, in addition to exposure and the littoral slope. The coast in Iceland has an estimated cover of 1,008 km2, including islands, skerries, and beach ridges. Beach ridges are typically narrow ridges of land above the high-tide mark that are shaped and strongly affected by the adjacent ocean.

How often and how long the various littoral zones are submerged or exposed to air are factors that shape the biota. The lower littoral zone is more frequently submerged than the uppermost littoral zone, and for longer periods of time. The mid littoral zone is a strip of shoreline that is consistently submerged and exposed by the changing tide. Exposed shores tend to remain damp longer than sheltered ones. Fine sand retains moisture better than coarse gravel, and ocean waves recede more quickly from more steeply inclined littoral slopes. Seawater may remain in depressions, hollows, and coastal gullies. Moisture is also retained longer on seaweed-covered shores than on bare rocky shores. On very exposed shores, most organisms are firmly anchored to the substrate, although motile animals may thrive in the shelter of the seaweed. More sheltered shores are home to larger numbers of motile animals. Other physical variables affecting coastal and littoral communities include salinity, temperature, shelter from drought, and sun exposure.

Classification and mapping of coastal habitat types is based on the EUNIS system, where applicable, and on data and classification from Dr. Agnar Ingólfsson. The uppermost levels of the EUNIS system take into account the littoral substrata, and the physical and chemical environment, such as exposure, ocean temperature, salinity, and climate. Classification at lower levels is based on the species composition of the biota, i.e., dominant vegetation and animal life. Icelandic coastal and littoral habitats are classified into 24 habitat types, organised hierarchically into four levels. The broadest classification (Level 1) is that of littoral shores. Level 2 divides these habitats into rocky shores or sandy and muddy shores. These, in turn, are classified into more specific habitat types at Levels 3 and 4 and in few cases down to Level 5.

Fact sheets

Fact sheets on littoral habitat types provide concise but detailed descriptions of each habitat type, a list of characteristic species, and two photographs. The rough distribution of habitat types is shown on a basic 10x10 km grid square map. A more detailed map can be accessed in the map viewer.


F1 Grýttar fjörur A1 Littoral rock and other hard substrata
F1.1 Hrúðurkarlafjörur A1.11 Mussel and/or barnacle communities
F1.2 Brimasamar hnullungafjörur New type, suggestion. A1.13 Ephemeral algae on boulder shores
F1.3 Þangfjörur A1.2 Moderate energy littoral rock, A1.3 Low energy littoral rock
F1.31 Klóþangsfjörur A1.31 Fucoids on sheltered marine shores 
F1.32 Bóluþangsfjörur A1.21 Barnacles and fucoids on moderately exposed shores
F1.33 Skúfþangsfjörur New type, suggestion. A1.25 Fucus disticus on moderate/high energy littoral rock
F1.34 Sagþangsfjörur A1.31 Fucoids on sheltered marine shores
F1.35 Þangklungur A1.31 Fucoids on sheltered marine shores, A1.32 Fucoids in variable salinity
F1.35.1 Klóþangsklungur A1.3142 Ascophyllum nodosum on full salinity mid eulittoral mixed substrata
F1.35.2 Bóluþangsklungur A1.323 Fucus vesiculosus on variable salinity mid eulittoral boulders and stable mixed substrata
F2 Setfjörur A2 Littoral sediment
F2.1 Líflitlar sandfjörur A2.2 Littoral sand and muddy sand
F2.11 Brimasamar sandfjörur A2.22 Barren or amphipod-dominated mobile sand shores
F2.2 Óseyrar A2.12 Estuarine coarse sediment shores
F2.21 Kræklinga- og sölvaóseyrar New type, suggestion. A1.13 Mytilus and Palmaria estuarine/estuary shore
F2.3 Leirur A2.3 Littoral mud
F2.31 Sandmaðksleirur A2.241 Macoma balthica and Arenicola marina in muddy sand shores
F2.32 Kræklingaleirur A2.24 Polychaete/bivalve-dominated muddy sand shores
F2.33 Skeraleirur A2.322 Hediste diversicolor in littoral mud
F2.34 Gulþörungaleirur A2.323 Tubificoides benedii and other oligochaetes in littoral mud
F2.35 Marhálmsgræður A2.61 Seagrass beds on littoral sediments
F2.4 Grýttur sandleir A2.4 Littoral mixed sediments
F2.5 Fjörumór A1.127 Ceramium sp. and piddocks on eulittoral fossilised peat
FX Sérstæð fjörusvæði X Habitat complexes
FX.1 Sjávarlón X02 Saline coastal lagoonsX03 Brackish coastal lagoons
FX.11 Háseltulón X02 Saline coastal lagoons
FX.12 Leirulón X03 Brackish coastal lagoons
FX.2 Fjörupollar A1.41 Communities of littoral rockpools, A1.42 Communities of rockpools in the supralittoral zone
FX.3 Árósar X01 Estuaries