|Basic Information||Biotope classification||Ecology||Habitat preferences and distribution||Species composition||Sensitivity||Importance|
Image Sarah Fowler - Maerl bed in Loch Gairloch, Highland. Image width ca 2 m in foreground.
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SS.SMp.Mrl.Pcal.Nmix recorded () and expected () distribution in Britain and Ireland (see below)
For a list of 2004 characterising species please see the JNCC website.
To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.
|Community Importance||Species name||Common Name|
|Key structural||Phymatolithon calcareum||Maerl|
|Important characterizing||Nemertesia ramosa||A hydroid|
|Important characterizing||Neopentadactyla mixta||Gravel sea cucumber|
The biotope IGS.Phy.Hec occurs at greater depths than other maerl biotopes and consequently has fewer algal species. The community within the maerl bed is dominated by infaunal molluscs (Hall-Spencer & Atkinson, 1998) although hydroids and echinoderms may be the most apparent on the surface. The biotope is partly named after these more obvious groups of organisms (hydroids and echinoderms). Two species typical of the biotope that represent these groups are Nemertesia ramosa and Neopentadactyla mixta and these species have been selected to represent the sensitivity of their relevant group. N.B. These two species are often but not necessarily always present in this biotope. Other similar species may be present in addition to or in place of these two species. In order to try and give an idea of the sensitivity of the biotope, Nemertesia ramosa and Neopentadactyla mixta have been used as species indicative of sensitivity for these obvious groups. Even if these species are not present or other species within the group (e.g. Nemertesia antennina, Ophiothrix fragilis are more faithful or abundant, the sensitivity assessments can give a broad impression of the sensitivity of the biotope. In undertaking an assessment of sensitivity of this biotope, account is taken of knowledge of the biology of all characterizing species in the biotope. However, the selected 'indicative species' are particularly important in undertaking the assessment because they have been subject to detailed research.
This review can be cited as follows:
Jackson, A. 2006. Phymatolithon calcareum maerl beds with hydroids and echinoderms in deeper infralittoral clean gravel or coarse sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 19/09/2014]. Available from: <http://www.marlin.ac.uk/habitatreproduction.php?habitatid=64&code=2004>