Coral gardens

Coral gardens © JNCC

When we think of corals, we think of shallow, warm tropical seas, not the cold, dark oceans around Britain.  However, in varying depths of water – typically from 30m to several thousand metres deep on underwater mountains – there are beautiful coral gardens.  They are made up of dense aggregations of colonies of one or more coral species and includes hard cold-water corals as well as soft corals.  In some locations, there may be up to 700 colonies in an area of one hundred square metres.

Coral gardens occur in water temperatures of between 3 and 8ºC, and can be found on different types of seabed.  Some corals need a hard surface to attach to when they first begin to grow from larvae, while others, such as sea pens are found in muddy areas. 

Coral gardens provide a home for many other animals – there is not enough light for seaweeds to grow here.  Animals, living amongst the corals include:  basket, brittle and feather starfish, bivalves (with their paired, hinged shells), shrimp-like animals and deep-water fish.

It is thought that, like most coral communities, coral gardens may be threatened by seabed trawling operations and smothering.

Cold-water corals were discovered in the 18th century, but we still know very little about them as most are found in deep water, too deep for divers to explore.  Modern technology is helping us to discover more.

For the official habitat definition please see the documents listed below.

 

European distribution

Coral gardens are present, to varying degrees, across most regions of the north-east Atlantic.

 

Conservation status/need

Coral gardens fact

  • This is a UK BAP Priority Habitat (BAP habitats are now Habitats of Principal Importance/Priority Habitats).
  • Annex I of the Habitats Directive: Reefs
  • OSPAR List of Threatened and/or Declining Species and Habitats (Region II – Greater North Sea, Region III – Celtic Sea, Region V – Wider Atlantic)

 

Official definition

UK Biodiversity Action Plan; Priority Habitat Descriptions. BRIG (ed. Ant Maddock) 2008 (updated December 2011)

Descriptions of habitats on the OSPAR list of threatened and/or declining species and habitats (OSPAR agreement 2008/07).

 

Further information

OPSAR Commission - Background Document for Coral gardens

JNCC biotope classification - Coral reefs

JNCC - biogenic reefs: cold water corals

JNCC - UK BAP Priority Species and Habitats

National Maritime Museum - cold water corals

JNCC EUNIS habitat correlations table