|Basic Information||Biotope classification||Ecology||Habitat preferences and distribution||Species composition||Sensitivity||Importance|
SS.IGS.FaS.FabMag recorded () and expected () distribution in Britain and Ireland (see below)
|Distribution of biotope in Britain and Ireland||Recorded from the Shetland Islands, Orkney Islands, SE Scotland, NE England, the Isles of Scilly, Bristol Channel and Cardigan Bay.|
|National importance||Not available|
For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC
In stable, fine, compacted sands in the infralittoral and sublittoral fringe, communities occur that are dominated by venerid bivalves such as Chamelea gallina. The biotope may be characterized by a prevalence of Fabulina fabula and Magelona mirabilis. Remote grab sampling is likely to under-estimate deep-burrowing species such as Ensis sp. (Warwick & Davis, 1977). Slightly muddy examples may have low numbers of Mysella bidentata. The community is relatively stable in its species composition, unlike IGS.Sell, which is closely allied and collectively considered to be the 'shallow Venus community' or 'boreal off-shore sand association' of previous workers (see Petersen, 1918; Jones, 1950; Thorson, 1957). IGS.FabMag differs from IGS.Sell because of the prevalence of the brittle-shelled Fabulina fabula over the more robust Spisula elliptica and because it occurs in generally finer, more compacted sands. These communities have been shown to correlate well with particular levels of current induced 'bed-stress' (Warwick & Uncles, 1980). The 'Arctic Venus Community' and 'Mediterranean Venus Community' described to the north and south of the UK (Thorson, 1957) probably occur in the same habitat and appears to be the same biotope described as the Ophelia borealis community in northern France and the central North Sea (Kunitzer et al., 1992). In very shallow water and eulittoral sands this biotope may give way to IMS.MacAbr. Sites with this biotope may undergo transitions in community composition e.g. IMS.SpiSpi may be a transitional community between IGS.FabMag and CMS.AfilEcor (see Salzwedel, Rachor & Gerdes, 1985). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).
There is a degree of uncertainty concerning the habitat preferences of the species which characterize the IGS.FabMag biotope. The biotope appears to be based on the 'Tellina sub-community' described by Warwick & Davis (1977) and Warwick & Uncles (1980), which occurs in stable sands sheltered from big swells and with low tidal stress. The characterizing species are described as being fragile, for instance, Fabulina fabula with a "thin, brittle shell" and Magelona mirabilis with "long, delicate palps". The authors suggest that Fabulina fabula and Magelona mirabilis are absent from more dynamic areas with high sediment transport, where they are replaced by more robust species, such as Spisula elliptica and Nephtys cirrosa. However, literature research on the biology and ecology of Magelona mirabilis suggests it is a heavily r-selected opportunist species adapted to life in mobile sands (see Bosselmann, 1989; Niermann et al., 1990; Krönke, 1990). Additionally, Elliott et al. (1998) place IGS.FabMag in the 'subtidal mobile sandbanks' complex, where the composite species are adapted to variable hydrography and a mobile substratum.
It appears that the biotope is likely to contain elements of both relatively stable sands, characterized by climax species such as Fabulina fabula and Nephtys hombergii, and more dynamic sands, characterized by Spisula elliptica and Nephtys cirrosa. Even stable sands are liable to perturbations from variable environmental conditions and hence species characteristic of early successional stages, such as Magelona mirabilis, are able to persist.
For the purposes of this review, species characteristic of the biotope are assumed to be those favouring stable conditions, e.g. Fabulina fabula, and the characteristic opportunists, e.g. Magelona mirabilis.
This review can be cited as follows:
Rayment, W.J. 2006. Fabulina fabula and Magelona mirabilis with venerid bivalves in infralittoral compacted fine sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 23/05/2013]. Available from: <http://www.marlin.ac.uk/habitatsbasicinfo.php?habitatid=142&code=1997>