Biodiversity & Conservation

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

In deep water and soft muds of Boreal and Arctic areas, a community dominated by foraminiferans and the bivalve Thyasira sp. may occur (Thorson, 1957; Kunitzer et al., 1992). This community typically occurs in water deeper than 100 m in the northern North Sea (Kunitzer et al., 1992) and have been referred to as 'Foraminifera communities' by other workers (e.g. Stephen, 1923; Thorson, 1957; McIntyre, 1961). Foraminiferans such as Saccammina sp., Psammosphaera sp., Crithionina sp. and Astorhiza sp. are important components of this community with dead tests numbering thousands per m² (see Stephen, 1923; McIntyre, 1961) and sometimes visible from benthic photography (Mackie et al., 1995). It is likely that a community dominated by Astorhiza in the Irish Sea is another distinct biotope (E.I.S. Rees pers comm., 1997). Polychaetes, e.g. Paraonis gracilis, Myriochee heeri, Spiophanes kroyeri, Tharyx sp., Lumbrineris tetraura, are also important components of this biotope. These communities appear to have no equivalent on the continental plateau further south (Glemarec, 1973) but are known from the edge of the Celtic Deep in the Irish Sea (Mackie et al., 1995). The benthos in these offshore areas has been shown to be principally Foraminifera and similar, rich communities may exist in Scottish sea lochs (McIntyre, 1961). Shallower water may give rise to Brissopsis lyrifera dominated communities (CMU.BriAchi). Communities from yet deeper (northern) waters at the extremes of the North Sea may be reminiscent, although dissimilar to COS.ForThy (see Pearson et al., 1996) reflecting a higher proportion of silt/clay. A fully Arctic version of this biotope has also been described (Thorson, 1934, 1957) although it should be noted that Jones (1950) considered this Boreal foraminiferan community to be part of a 'Boreal Deep Mud Association'. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

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