MNCR Code MCR.Oph

MNCR Code MCR.Oph.Oacu

The MNCR biotope classification provides a hierarchical framework for differentiating and classifying the shallow-water benthic habitats and biological communities of the British Isles (Connor et al., 1997). The basic unit of classification is the Biotope, a recognisable Community of conspicuous species occurring in a Habitat, defined according to parameters of the physical environment such as substratum type or degree of wave exposure. Groups of biotopes with similar overall character, suitable for local mapping where biotopes consistently occur together and are relatively restricted in their extent, are termed Biotope complexes. The current version of the MNCR biotope classification (Connor et al., 1997) lists two biotopes characterized by high abundances of epifaunal brittlestars. These are summarized below:

Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata.

Moderately exposed or sheltered slightly tide-swept rock or mixed substrata with dense brittlestar beds, usually dominated by Ophiothrix, but often with Ophiocomina amongst them. Ophiocomina may be the dominant species at some sites. Crusts of coralline algae occur on the underlying rocks, along with the tubeworm Pomatoceros triqueter. Alcyonium digitatum and a few species of sea anemones and hydroids may occur sparsely on protruding rocks. The large predatory starfish Luidia ciliaris and Crossaster papposus are also typically present. This biotope represents the ‘standard’ brittlestar bed type, and occurs widely around the British Isles (see Section B below).

Ophiopholis aculeata beds on slightly tide-swept circalittoral rock or mixed substrata.

This is a variant of the MCR.Oph biotope, distinguished by the occurrence of large numbers of Ophiopholis aculeata (Ophiothrix and Ophiocomina are also common in this biotope). Physical conditions and associated fauna are similar to those of MCR.Oph. Ophiopholis - dominated beds are rare, known from localities in Shetland, Ireland and in the Loch Alsh/Duich/Long system in the west of Scotland (Connor, 1989).

A few other biotopes defined in the MNCR system may support brittlestars in large numbers, but not consistently, or not in such abundance as to constitute ‘beds’.

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