Biological zones
Terms used to describe coastal and marine biological zones
| Zone | Definition |
|---|---|
| Neritic | Water column overlying the continental shelf; surface to ca 200 m depth. |
| Oceanic | Open waters beyond the continental shelf. |
| Benthic | Living on or in the seabed or river bed. |
| Supralittoral | The lower terrestrial zone, characteristically dominated by orange and white-to-grey lichens on hard substrata with scattered salt-tolerant higher plants and mosses. |
| Spray Zone | Region of the shore immediately above the splash zone that is subject to wetting by the spray from breaking waves (Lincoln et al., 1998) |
| Splash Zone | Region of the shore immediately above the highish levels of the water that is subject to wetting by splash from breaking waves (Lincoln et al., 1998). |
| Eulittoral | The region of the shore between the highest and lowest extent of the tides (rephrased from Lincoln et al., 1998). |
| Upper Littoral Fringe | This is colonized by Verrucaria maura with Littorina saxatilis and Littorina neritoides often present. May include salt marsh species on shale/pebbles in shelter. |
| Lower Littoral Fringe | The Pelvetia/Porphyra belt with patchy Verrucaria maura and Fucus spiralis (on sheltered shores). Fucus distichus and Fucus spiralis nana occurs on extremely exposed shores in the North East. Verrucaria mucosa present above the main barnacle population. May also include salt marsh species on shale/pebbles in shelter. |
| Upper Eulittoral | Barnacles and limpets present in quantity with Fucus vesiculosus and Ascophyllum, although this belt often has only sparse algal cover compared with the lower eulittoral. |
| Mid Eulittoral | Barnacle - limpet dominated, sometimes mussels, with Fucus vesiculosus and Ascophyllum nodosum. Mastocarpus stellatus and Palmaria palmata patchy in lower part. Usually quite a wide belt. |
| Lower Eulittoral | Zone characterized by Fucus serratus, Mastocarpus stellatus, Himanthalia elongata and Palmaria palmata present; sparse barnacles on rocky shores. Patchy Alaria may be present. |
| Sublittoral | The zone exposed to air only at its upper limit by the lowest spring tides, although almost continuous wave action on extremely exposed coasts may extend the upper limit high into the intertidal region. The sublittoral extends from the upper limit of the large kelps and includes, for practical purposes in nearshore areas, all depths below the littoral (based on Hiscock, 1985). The marine zone extending from the lowest limit of the intertidal to the outer edge of the continental slope (rephrased from Lincoln et al., 1998). |
| Sublittoral Fringe | The upper part of the sublittoral zone that is uncovered by the tide. On hard substrata, the zone is characterized by the kelps Laminaria digitata and Alaria esculenta. The lower limit of this zone is marked by the upper limit of the truly sublittoral kelp Laminaria hyperborea. This species assemblage does not occur on all British coasts (based on Lewis, 1964). |
| Infralittoral | A subzone of the sublittoral in which upward-facing rocks are dominated by erect algae, typically kelps; it can be further subdivided into the upper and lower infralittoral (based on Hiscock, 1985). The term is also used by Glémarec (1973) to refer to areas (étages) with a eurythermal environment of great seasonal and also daily and tidal amplitude. |
| Upper Infralittoral | The part of the infralittoral subzone which, on hard substrata, is dominated by Laminariales forming a dense canopy, or kelp forest (based on Hiscock, 1985). |
| Lower Infralittoral | The part of the infralittoral subzone which, on hard substrata, supports scattered kelp plants (a kelp park) or from which kelps are absent altogether and the seabed is dominated by foliose red and brown algae. It may be difficult to distinguish the lower infralittoral where grazing pressure prevents the establishment of foliose algae (based on Hiscock, 1985). |
| Circalittoral | The subzone of the rocky sublittoral below that dominated by algae (the infralittoral), and dominated by animals. No lower limit is defined, but species composition changes below about 40m to 80m depth, depending on depth of the seasonal thermocline. This subzone can be subdivided into the upper circalittoral where foliose algae are present and the lower circalittoral where they are not (see Hiscock, 1985). The term is also used by Glémarec (1973) to refer to two étages of the sediment benthos below the infralittoral: a "coastal circalittoral category with a eurythermal environment of weak seasonal amplitude (less than 10°C) varying slowly" and a "circalittoral category of the open sea with a stenothermal environment" (McLeod, 1996). |
| Upper Circalittoral | Dominated by animals with sparse foliose algae except where grazed. The part of the circalittoral subzone on hard substrata distinguished by the presence of scattered foliose algae amongst the dominating animals; its lower limit is the maximum limit of depth for foliose algae (based on Hiscock, 1985). |
| Lower Circalittoral | Dominated by animals with no foliose algae but encrusting Rhodophycota patchy in grazed areas. The part of the circalittoral subzone on hard substrata below the maximum depth limit of foliose algae (based on Hiscock, 1985). |
| Circalittoral Offshore | Typically occurs below 50-70 metres away from the influence of wave action. Aphotic with animal communities in stable or stenothermal and stenohaline conditions. Open sea (Connor et al., 1997). |
| Bathybenthic (Bathyal) | Occupying the ocean floor from ca 200 - 4000 m depth (Lincoln et al., 1998). |
| Abyssobenthic (Abyssal) | Occupying the ocean floor from ca 4000 - 6000 m depth. Usually a more or less flat plain. (Lincoln et al., 1998). |
| Hadobenthic (Hadal) | Occupying the ocean floor at depths exceeding ca 6000 m. Usually in trenches and canyons of the abyssal zone. (Lincoln et al., 1998). |
| Pelagic | Pertaining to the water column of the ocean or lake. Inhabiting the open sea, excluding the sea floor (rephrased form Lincoln et al., 1998). |
| Epipelagic | The photic zone, includes the open ocean influenced by light. The lower boundary is dependent on the depth of light penetration and is generally regarded extend to ca 200m in depth. |
| Mesopelagic | The upper aphotic zone and extends to a depth of ca 1000 m. |
| Bathypelagic | Extends from ca 1000 -2500 m. |
| Hadopelagic | Open waters of deep oceanic trenches, from ca 6000 m and below. |
| Benthopelagic | A zone of open water extending ca 100 m above the surface of the sea bed at all depths below the edge of the continental shelf. |
| Ice-associated | Sea ice, iceberg and other ice-associated marine habitats. |
| Anchialine caves | Coastal salt water habitats with no surface connection to the sea. |
References
- Connor, D.W., Brazier, D.P., Hill, T.O. & Northen, K.O., 1997. Marine Nature Conservation Review: Marine biotope classification for Britain and Ireland. Volume 1. Littoral biotopes. Version 97.06. Joint Nature Conservation Committee, Peterborough, JNCC Report, no. 229.
- Hiscock, K., 1985. Aspects of the ecology of rocky sublittoral areas. In Moore, P.G. and Seed, R. (eds.). The ecology of rocky coasts: essays presented to J.R. Lewis D.Sc. London: Hodder and Stoughton, pp. 290-328.
- Hiscock, K., 1990. Marine Nature Conservation Review: methods. Joint Nature Conservation Committee, Peterborough, Nature Conservancy Council, CSD Report, No. 1072. (Marine Nature Conservation Review Report, No. MNCR/OR/5.).
- Lewis, J.R., 1964. The ecology of rocky shores. London: English Universities Press.
- Lincoln, R., Boxshall, G. & Clark, P., 1998. A dictionary of ecology, evolution and systematics (2nd ed.). Cambridge: Cambridge University of Press.
