Boundaries

This ecoregion encompasses the islands of Iceland and Jan Mayen, which fall roughly halfway between Greenland and Europe. The islands are separated by 600 km and lie within the North Atlantic and Arctic oceans.

Topography

Iceland is the largest volcanic island in the North Atlantic Ocean. Situated directly on the Mid-Atlantic Ridge between the Eurasian and North Atlantic Plates, it is geologically active with many geysers, hot springs, and volcanoes such as Hekla, Katla, Krafla, and Grímsvötn. It is composed of basaltic lavas and pyroclastics. Glaciers cover more than 11% of the island, with Vatnajökull being the largest at 8300 km2 in surface area, as well as the third largest on earth after Antarctica and Greenland (Gillespie & Clague 2009). Other glaciers include Langjökull, Hofsjökull, Mýrdalsjökull, and Drangajökull. Over time these have helped shaped the landscape, cutting fjords deep into the west, north and eastern side of the island. The southern part of the island is characterized by lava flats and alluvial plains. More than half of the island lies on a plateau above 400 m asl (Brittain et al. 2009). Lying on the Jan Mayan Ridge, Jan Mayen is a relatively young island composed of basaltic lavas and tephra. It is divided into two parts separated by an isthmus: Nord-Jan is the wider, northern extension and Sør-Jan is the narrow and flatter southern extension. Nord-Jan has numerous glaciers and is dominated by the Beerenberg Volcano, the highest peak on the island at 2277 m asl. In comparison, Sør-Jan is flatter with its highest elevation at 769 m asl. It is also unglaciated. The coastline is characterized by high and low sea cliffs, rocky shores, and stony beaches (Bird 2010).

Freshwater habitats

Rivers in Iceland are short, but may experience high seasonal flows due to melting ice and snow. The types of rivers include glacial rivers with high summer discharge and large sediment flow, high turbidity and unstable substrates; direct runoff rivers with the highest discharge during the spring thaw; and spring-fed rivers with low fluctuation in discharge and relatively stable river beds. Rivers that originate from or flow through volcanic areas typically have higher concentrations of total dissolved solids and nutrients. The Geithellnaá River, for example, collects runoff from the Vatnajökul ice sheet. Its mean annual discharge varies from 10-25 m3/s, depending on yearly rainfall. The Laxá River, in contrast, drains Lake Mývatan, which is fed by warm and cold springs. The Laxá flows 58 km through waterfalls in the Laxárgljúfur canyon before reaching the Arctic Ocean. At its mouth its mean annual discharge is 55 m3/s (Brittain et al.2009). The Laxá-Mývatan area is a Ramsar site that includes freshwater marshes, submerged flora, algal communities, Betula woodland, bogs, and moorland (Wetlands International 2005).

The largest lakes in Iceland are Þingvallavatn, which is primarily a spring-fed lake, and Þórisvatn, which is a reservoir. Other important lakes include Lagarfljót and Mývatn. Mývatn is one of the most productive lakes in northern Europe due to high solar radiation and nutrient inputs from warm and cold springs (Brittain et al. 2009). Jökulsárlón, a glacial lagoon, is also the deepest lake on the island. It formed from the receding Vatnajökull ice sheet, and is located just 1.5 km from the Atlantic Ocean.

Two of the largest water bodies on Jan Mayen are Sørlaguna (South Lagoon), which dries out during the summer, and Nordlaguna (North Lagoon), which is 40 m deep (Bird 2010). There is also Ullerenglaguna (Ullereng Lagoon). Other lakes include Strandvatnet and Vassbergtjorna.

Terrestrial habitats

The Iceland boreal birch forests and alpine tundra [PA0602] ecoregion is the main terrestrial ecoregion of Iceland. Other areas of rock and ice are dominated by glaciers, which cover more than 11% of the island. The island is mainly bare, with limited wooded areas and large areas devoid of vegetation or covered by only sparse vegetation. Lava flows and volcanic ash have affected vegetation cover. Some of the larger trees include dwarf birch (Betula nana), downy birch (B. pubescens), mountain ash (Sorbus aucuparia), and willow (Salix phylicifolia). Other indigenous species include lichens (Cetraria nivalis, Xanthoria elegans, X. candelaria, Alectoria ochroleuca), sorrel (Rumex acetosa), and sedges (Carex chordorrhiza, Carex rostrata) (WWF 2001).

Arctic desert [PA1101] characterizes the island of Jan Mayen (WWF 2001). Its sparse vegetation cover is dominated by mosses, lichens and grasses, most of which are circumpolar. Its only endemics are dandelions (Taraxacum) (Gillespie & Clague 2009).

Description of endemic fishes

The isolated Lake Thingvallavatn has endemic species or local forms of the genus Salvelinus, including murta (Salvelinus murta), gjámurta (S. thingvallensis), and the large benthivorous Thingvallavatn charr (Salvelinus sp. Thingvallavatn large benthisvorous) (Kottelat & Freyhof 2007). The main differences occur in their morphology (Sandlund et al. 1992).

Ecological phenomena

Migratory species in the ecoregion include the catadromous European eel (Anguilla anguilla) and anadromous three-spined stickleback (Gasterosteus aculeatus), Atlantic salmon (Salmo salar), Atlantic trout (S. trutta), and Arctic charr (Salvelinus alpinus) (Kottelat & Freyhof 2007). These upstream migrations are an important source of marine-derived nutrients to these rivers, which tend to be nutrient-poor (Brittain et al. 2009).

Justification for delineation

Northern European ecoregions were delineated through a top-down process using major basins as a starting point and incorporating traditionally recognized zoogeographic patterns where appropriate (Abell et al. 2008). This ecoregion represents two isolated islands with few freshwater fish species, but several isolated lakes with endemic Salvelinus species and local forms (Sandlund et al. 1992).

Level of taxonomic exploration

Fair