Distribution

Global - potentially in all seas and at all latitudes

Global - in sub-tropical and tropical seas between 30ºN and 30ºS

Number of states, countries and territories with corals

41 so far

109

Coverage

Unknown - but studies to date indicate that global coverage of cold-water coral reefs could equal, or even exceed, that of warm-water reefs

284,300 km²

Country with highest coral reef coverage

Unknown – the total amount of reefs in Norwegian waters alone was roughly estimated to cover at least 2,000 km²

Indonesia (51,020 km²)

Largest reef complex

Unknown – so far, the Røst Reef (100 km²) discovered in 2002 in northern Norway is regarded as the largest reef

Great Barrier Reef (more than 30,000 km²), Australia

Temperature range

4º – 13º C

20º - 29º C

Salinity range

32 – 38.8 ‰

33 – 36 ‰

Depth range

40 – beyond 1,000m

0 – up to 100 m

Nutrition

Uncertain, but likely suspended organic matter and zooplankton

Suspended organic matter and photosynthesis

Symbiotic algae

No

Yes

Growth rate

4 – 25 mm / year

Up to 150 mm / year

Number of reef building coral species

Few - only 6 primary species.

Around 800

Reefs composition

Mostly composed of one or few coral species

Mostly composed of numerous coral species

Age of living reefs

Up to 8,000 years

6,000 – 9,000 years

Status

Unknown – but most reefs studied so far show signs of physical damage. Some reefs in the NE Atlantic have been lost completely due to bottom trawling.

30% irreversibly damaged, another 30% at severe risk of being lost in the next 30 years

Rate of Regeneration / recovery

Unknown - slow growth rate indicates that if regeneration / recovery is possible at all, it might take decades to centuries for a damaged reef to regain its ecological function

Slow (years to decades) - in most cases, regeneration / recovery will lead to reduced coral diversity, a shift in coral species composition, or even a change from a coral to an algae dominated ecosystem especially where humans impacts are evident

Main natural and climate change induced threats

Unknown – climate change could a.o. cause changes in current systems which could affect food supply in deeper waters.

Increased episodes of higher than normal sea temperatures leading to more widespread and lethal coral bleaching

Main threats from human activities

Ecological importance

Reefs provide habitat, feeding grounds, recruitment and nursery functions for a range of deep-water organisms, including commercial fish species. The number of species depending on or associated with these reefs, and their full ecological importance/value, is still unknown.

An estimated 1 million plant and animal species are associated with warm water coral reefs. There are approximately 4000 coral reef fish species (¼ of all marine fish species).

Socio-economic importance

Unknown – but initial observations suggest importance for local fisheries, including coastal line / net fisheries and deep-water fisheries (especially around seamounts)

Reefs provide coastal protection and a source of livelihood for more than 1 billion people. The net potential benefits provided reefs are estimated at US$ 30 billion / year.

International awareness and attention

Increased over the last 2-3 years.

Increasing over the last 1-2 decades, especially after bleaching events in the 90s, with more than 100 non- and intergovernmental organisations engaged in work on warm-water reefs.