Substratum or habitat types
| Hard (immobile) Immobile hard substratum e.g. solid rock, concrete but inc. soft rocks , such as chalk . |
Artificial (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. | ||
| Hard (mobile) 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 that are predominantly pebbles. | ||
| Sediment / soft Definitions from Hiscock (1996) and Long (2006) |
Coarse sediment | 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 | ||
| Substratum (other) | Definition |
|---|---|
| Biogenic reef | An elevated structure on the seabed built by calcareous or other concretion-forming organisms, or by chemical precipitation (Hiscock, 1996) e.g. reefs of 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) |
| Macroalgae | 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). |
References
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.
