Biodiversity & Conservation

Maerl - Lithothamnion glaciale

Lithothamnion glaciale

Image Christine Howson - Lithothamnion glaciale nodules amongst pebbles with the sunstar Crossaster papposus, Isle of Lewis. Image width ca 20 cm.
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Distribution map

Lithothamnion glaciale recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

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Lithothamnion glaciale is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Rhodophyta Red seaweeds
Class Florideophyceae
Authority (Kjellman), 1883
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Most abundant in the sea lochs of western Scotland, Orkney and Shetland. Recorded along the east coast south to Flamborough. Occasional on the south coast, Wales, Isle of Man and Lundy. Sparse records from north and south-western Ireland.
Habitat information icon Habitat information Lithothamnion glaciale occurs in two main growth forms - as a thin encrusting species on rock, boulders, pebbles and shells etc. and also as a loose-lying algal gravel. This species occurs mainly in the mid-lower regions of the photic zone where there is considerable but not excessive water movement, either from wave exposure or tidal currents.
Text page icon Description The form of this calcareous alga is very variable. It occurs in two main forms, a thin, hard crust on hard substrata as well as an unattached, fragile, branched nodules. When young, the crustose form is smooth with some scattered young mounds but develops branches with age. The loose-lying nodules may form dense beds of algal gravel. Encrusting individuals may reach up to 20 cm across and free-living plants may reach 4 - 5 cm across. In the free-living form the branches are up to 4 mm in diameter and 15 mm in length. The plants, when alive, are reddish to deep pink in colour with a violet tinge and white when dead.
Identifying features
  • Forms a branching crust or a free-living branching nodule.
  • Smooth, matt surface.
  • Branches hard, not brittle.
  • Branch diameter variable but up to 4 mm.
  • Reddish to deep pink with violet tinge.
  • May be an important component of maerl beds.
Additional information icon Additional information This genus was previously called Lithothamnium but now Lithothamnion is the preferred name. Previous classifications included two varieties (sometimes formerly given species status): Lithothamnium granii (Foslie); and Lithothamnium colliculosum. It is quite difficult to differentiate between Lithothamnion glaciale and Lithothamnion corallioides. The hard surface and the absence of numerous surface mounds on Lithothamnion glaciale may help separate them although for greater accuracy the cortical cell structure should be used.

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This review can be cited as follows:

Angus Jackson 2003. Lithothamnion glaciale. Maerl. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=3711>