You are here:
Eionet
Data Dictionary
Vocabulary

Concept: [Ophiothrix fragilis] and/or [Ophiocomina nigra] brittlestar beds on sublittoral mixed sediment in the eunishabitats vocabulary

Concept URI http://eunis.eea.europa.eu/eunishabitats/A5.445
Preferred label [Ophiothrix fragilis] and/or [Ophiocomina nigra] brittlestar beds on sublittoral mixed sediment
Definition Circalittoral sediment dominated by brittlestars (hundreds or thousands m-2) forming dense beds, living epifaunally on boulder, gravel or sedimentary substrata. [Ophiothrix fragilis] and [Ophiocomina nigra] are the main bed-forming species, with rare examples formed by [Ophiopholis aculeate]. Brittlestar beds vary in size, with the largest extending over hundreds of square metres of sea floor and containing millions of individuals. They usually have a patchy internal structure, with localized concentrations of higher animal density. [Ophiothrix fragilis] or [Ophiocomina nigra] may dominate separately or there may be mixed populations of the two species. [Ophiothrix] beds may consist of large adults and tiny, newly-settled juveniles, with animals of intermediate size living in nearby rock habitats or among sessile epifauna. Unlike brittlestar beds on rock, the sediment based beds may contain a rich associated epifauna (Warner, 1971; Allain, 1974; Davoult & Gounin, 1995). Large suspension feeders such as the octocoral [Alcyonium digitatum], the anemone [Metridium senile] and the hydroid [Nemertesia antennina] are present mainly on rock outcrops or boulders protruding above the brittlestar-covered substratum. The large anemone [Urticina feline] may be quite common. This species lives half-buried in the substratum but is not smothered by the brittlestars, usually being surrounded by a 'halo' of clear space (Brun, 1969; Warner, 1971). Large mobile animals commonly found on Ophiothrix beds include the starfish [Asterias rubens], [Crossaster papposus] and [Luidia ciliaris], the urchins [Echinus esculentus] and [Psammechinus miliaris], edible crabs [Cancer pagurus], swimming crabs [Necora puber], [Liocarcinus] spp., and hermit crabs [Pagurus bernhardus]. The underlying sediments also contain a diverse infauna including the bivalve [Abra alba]. Warner (1971) found that numbers and biomass of sediment dwelling animals were not significantly reduced under dense brittlestar patches.
Notation A5.445
Status Valid
Status Modified 2014-01-31
Accepted Date 2014-01-31
Not Accepted Date
Has broader
Has exact match