Biodiversity & Conservation

Halidrys siliquosa and mixed kelps on tide-swept infralittoral rock with coarse sediment.



Image Rohan Holt - Halidrys on flat pebbles and gravel. Image width ca 1 m.
Image copyright information

Distribution map

IR.MIR.SedK.HalXK recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Recorded distribution in Britain and Ireland

Recorded from tide-swept but generally wave sheltered habitats of Shetland and Orkney, north east England, the English Channel, the south west, Cardigan Bay and the Sarnau, western Ireland and western Scotland.

Habitat preferences

Temperature range preferences - Data deficient

Water clarity preferences - Medium clarity / Medium turbidity
Low clarity / High turbidity
High clarity / Low turbidity

Limiting Nutrients - Nitrogen (nitrates)
Phosphorus (phosphates)

Other preferences - Sediment abrasion.

Additional information

Halidrys siliquosa dominated communities may occur below the shallow water kelp dominated belt or form extensive beds where silt accumulation prevents kelps such as Laminaria hyperborea or Laminaria digitata becoming dominant e.g. Weymouth Bay (Dixon et al., 1978). Halidrys siliquosa dominated communities are characterized by species tolerant of silt and sediment abrasion and wave sheltered conditions but die out as the sediment substratum grain size decreases (i.e. shingle or coarse gravel) or water flow increases. However, this community is often associated with the entrance (or exit) of tidal rapids in Lochs, e.g. up to 1 -2 knots (0.5 -1m/sec) in Loch Yeor, west Uist (Lewis, 1964; Thorpe et al., 1998). With increasing water flow, Himanthalia elongata abundance within the biotope increases. At higher water flow rates found in rapids, or increased wave action, the biotope is replaced by Laminaria digitata or Laminaria hyperborea biotopes (e.g. EIR.LhypR or MIR.Ldig.Ldig) (Lewis, 1964; Connor et al, 1997a).

This review can be cited as follows:

Tyler-Walters, H. 2002. Halidrys siliquosa and mixed kelps on tide-swept infralittoral rock with coarse sediment.. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2015]. Available from: <>