Biodiversity & Conservation

Hydroids, ephemeral seaweeds and Littorina littorea in shallow eulittoral mixed substrata pools


Hydroids, ephemeral seaweeds and <i>%Littorina littorea%</i> in shallow eulittoral mixed substrata pools
Distribution map

LR.FLR.Rkp.H recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Marine natural heritage importance

Listed under
National importance Rare
Habitat Directive feature (Annex 1) Reefs
Large shallow inlets and bays

Biotope importance

LR.H is not thought to hold any significant importance for other species although the mussels that may be found in the biotope may be part of large mussel beds (SLR.MytX) which are highly productive, and offer refuge and food for a large variety of organisms. Seed & Suchanek (1992) suggested that in populations of older mussels, productivity may be in the region of 2000-14,500 kJ/m/yr. The Mytilus edulis beds probably also provide secondary productivity in the form of tissue, faeces and pseudofaeces (Seed & Suchanek, 1992; Holt et al., 1998). Larval production represents a significant contribution to the zooplankton, forming an important food source for herring larvae and carnivorous zooplankton (Seed & Suchanek, 1992). Dense beds of bivalve suspension feeders increase turnover of nutrients and organic carbon in estuarine (and presumably coastal) environments by effectively transferring pelagic phytoplanktonic primary production to secondary production (pelagic-benthic coupling) (Dame, 1996).


Both Littorina littorea and Mytilus edulis are targeted for extraction. Littorina littorea is gathered by hand at a number of localities, particularly in Scotland and in Ireland where the industry is valued at around £5 million per year.

Mussels have been harvested for food and bait since early times. British mussel production is relatively small, comprising only 5% of total Europe Community production (Edwards, 1997). Wild mussel fisheries are found in tidal flats of The Wash, Morecambe Bay, Solway and Dornoch Firths in Scotland and river estuaries such as Conwy, North Wales and the Teign and Taw, Devon (Edwards, 1997). Edwards (1997) notes that the commercial development of natural beds is hampered by sporadic and unpredictable recruitment. Extraction of Mytilus edulis from LR.H will most likely be by hand on a small scale.

Additional information icon Additional information

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This review can be cited as follows:

Marshall, C.E. 2005. Hydroids, ephemeral seaweeds and Littorina littorea in shallow eulittoral mixed substrata pools. 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: <>