Immobile hard substratum e.g. solid rock, concrete but inc. soft rocks , such as chalk .
|Artifical (man-made)||Man-made structures e.g. of metal, wood or concrete.|
|Bedrock||Any stable hard substratum, not separated into boulders or smaller sediment units. Includes soft rock-types such as chalk, peat and clay (Hiscock et al., 1999).|
|Large to very large boulders||Boulders >512 mm; likely to be stable (Hiscock, 1996).|
|Small boulders||256 - 512 mm. May be unstable.|
Mobile hard substratum, e.g. cobles, pebbles that are regularly moved by wave action
|Cobbles||64-256 mm. May be rounded to flat. Substrata that are predominantly cobbles.|
|Pebbles||16-64 mm. May be rounded to flat. Substrata which are predominantly pebbles.|
|Sediment / soft
Definitions from Hiscock (1996) and Long (2006).
|Gravel / shingle||4 -16 mm. Clean stone or shell gravel including dead maerl. >80% gravel.|
|Sandy gravel||50 -80% gravel, 20 -50% sand.|
|Gravelly sand||50 -80% sand, 20 -80% gravel.|
|Sand and muddy sand||Sand||0.063 - 4 mm. >80 % sand|
|Coarse clean sand||0.5 - 4 mm. >80 % sand.|
|Medium clean sand||0.25-1mm > 80 % sand.|
|Fine clean sand||0.063 - 0.5 mm. >80 % sand.|
|Sandy mud||50 - 80 % mud, 20 - 50 % sand|
Mud and muddy sand As defined by Long (2006).
|Muddy sand||50 - 80 % sand, 20 - 50 % mud.|
|Mud||<0.063 mm (silt / clay fraction). >80% mud.|
Mixed Mixtures of a variety of sediment types, composed of pebble / gravel / sand / mud. This category includes muddy gravels, muddy sandy gravels, gravelly muds, and muddy gravelly sands.
|Muddy gravel||50 - 80 % gravel, 20 - 50 % mud.|
|Gravelly mud||50 -80% mud, 20 -50% gravel.|
|Muddy sandy gravel||50 -80% gravel, 20 -50% mud and sand|
|Muddy gravelly sand||50 -80% sand, 20 -50% mud and sand|
|Sandy gravelly mud||50 -80% sand, 20 -50% mud and sand|
|Biogenic reef||An elevated structure on the seabed built by calcareous or other concretion-forming organisms, or by chemical precipitation (Hiscock, 1996). For example by Modiolus modiolus or Sabellaria alveolata.|
|Burrow dwellers||Occupies or shares space in burrow constructed by other organisms.|
|Caves||A large hollow in the side of a vertical rock face or cliff.|
|Crevices / fissures||Narrow openings (Thompson, 1995)|
|Macroalgea||Macroalgae surfaces, such as the fronds of kelps or fucoids.|
|Maerl||Calcareous nodules (rhodoliths) of maerl that may build up to form maerl beds|
|Seagrass||Habitat associated with seagrass bed communities.|
|Strandline||A line on the shore composing debris deposited by a receding tide; commonly used to denote the line of debris at the level of extreme high water (Lincoln et al., 1998).|
|Salt marsh||A flat, poorly drained coastal swamp inundated by most high tides (Lincoln et al., 1998).|
|Overhangs||An overhanging part of a rock formation (Thompson, 1995).|
|Other species||The surface of other species, e.g. shells or carapace.|
|Peat (fossilized)||A pure organic soil, the result of plant material accumulating in waterlogged conditions (from Fitter & Manuel, 1986). Fossilized peat may also be exposed and provide a unique substratum in the intertidal.|
|Rockpools||A pool of water among rocks left behind by the ebbing tide|
|Under boulders||Habitat associated with the underside of boulders.|
|Wrecks||Remains of sunken vessels (boats and ships).|
Connor, D.W., Allen, J.H., Golding, N., Howell, K.L., Lieberknecht, L.M., Northen, K.O. & Reker, J.B., 2004. The Marine Habitat Classification for Britain and Ireland. Version 04.05. Joint Nature Conservation Committee, Peterborough. Available from: <www.jncc.gov.uk/MarineHabitatClassification>
Fitter, R. & Manuel, R., 1986. Collins field guide to freshwater life of Britain and north west Europe. London: Collins.
Hiscock, K. (ed.), 1996. Marine Nature Conservation Review: rationale and methods. Peterborough: Joint Nature Conservation Committee. [Coasts and seas of the United Kingdom. MNCR series.]
Lincoln, R., Boxshall, G. & Clark, P., 1998. A dictionary of ecology, evolution and systematics (2nd ed.). Cambridge: Cambridge University of Press.
Long D. (2006). BGS detailed explanation of seabed sediment modified Folk classification. http://www.emodnet-seabedhabitats.eu/PDF/GMHM3_Detailed_explanation_of_seabed_sediment_classification.pdf
Thompson, D., (ed.) 1995. The Concise Oxford Dictionary of Current English. 9th ed. London: Oxford University Press.
Wentworth, C.K., 1922. A scale of grade and class terms for clastic sediments. Journal of Geology, 30, 377-392.