Biodiversity & Conservation

Foraminiferans and Thyasira sp. in deep circalittoral soft mud


Foraminiferans and <i>Thyasira</i> sp. in deep circalittoral soft mud
Distribution map

SS.SMu.OMu.ForThy recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • UK_BAP

Recorded distribution in Britain and Ireland

Recorded from a few isolated sites in the northern North Sea, the Celtic Deep and Scottish lochs on the Atlantic coast.

Habitat preferences

Temperature range preferences -

Water clarity preferences - Oceanic water

Limiting Nutrients - No information found

Other preferences -

Additional information

  • Differences in the faunal composition between Atlantic (Loch Nevis, Scotland) and northern North Sea sites (Forties oil field & Fladen Ground) have been described.
    • In the northern North Sea high densities of Saccammina sp., Psammosphaera sp., Astrohiza arenaria (Foraminifera), Thyasira equalis (bivalve) and Polychaetes such as Spiophanes kroyeri and Tharyx sp. were present in abundance (McIntyre, 1961; Hartley, 1984; Stephen, 1923). Whereas, in the Atlantic high densities of Crithionina granum (foraminifera), Thyasira flexuosa (bivalve) and Polychaetes were present in abundance McIntyre (1961).
    • Densities of foraminifera varied as follows; Stephen (1923) found 1074/m² of Saccammina sp. and Psammosphaera sp., and 190/m² of Astrorhiza arenaria. McIntyre (1961) found that in the Fladen Grounds dead tests of Saccammina sp. were more abundant (>10,000/m²) and Astrorhiza arenaria was not as common. However, the number of live foraminifera species would probably be much less; McIntyre (1961) estimated the abundance of living Saccammina sp. to be 263/m².
  • At sites in the northern North Sea, communities live in constant Boreal water where the bottom temperature among foraminifera communities has been noted to have a low range (Stephens, 1923), with temperatures and salinities remaining fairly constant, oscillating between 6 and 8°C and salinities of 35.20-35.26ppm (McIntyre, 1961). However, the Atlantic community lives in varying Boreal water (McIntyre, 1961).
Ockelmann (1958) indicated that records of Thyasira flexuosa in east Greenland and Jan Mayen were thought to actually refer to Thyasira gouldi and Thyasira equalis respectively, as Thyasira flexuosa has a boreal-lusitanian main distribution and is absent from arctic waters.

This review can be cited as follows:

Riley, K. 2002. Foraminiferans and Thyasira sp. in deep circalittoral soft mud. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/11/2015]. Available from: <>