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Biodiversity & Conservation

Biological zones

BENTHIC ZONES

Definitions (from Hiscock, 1990 unless otherwise stated)
SUPRALITTORAL FRINGE The lower terrestrial zone, characteristically dominated by orange and white-to-grey lichens on hard substrata with scattered salt-tolerant higher plants and mosses .
UPPER LITTORAL FRINGE This is colonized by Verrucaria maura with Littorina saxatilis and Littorina neritoides often present. May include saltmarsh 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 NE. Verrucaria mucosa present above the main barnacle population. May also include saltmarsh species on shale/pebbles in shelter.
UPPER EULITTORAL Barnacles and limpets present in quantity with Fucus vesiculosus and Ascophyllum although often this belt 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 Fucus serratus, Mastocarpus stellatus, Himanthalia elongata and Palmaria palmata present; sparse barnacles. Patchy Alaria.
SUBLITTORAL FRINGE Dominated by Alaria esculenta, Laminaria digitata or L. saccharina with sparse barnacles and encrusting Rhodophycota.
UPPER INFRALITTORAL Kelp forest.
LOWER INFRALITTORAL Sparse or no kelp , dominated by foliose algae except where grazed.
UPPER CIRCALITTORAL Dominated by animals with sparse foliose algae except where grazed.
LOWER CIRCALITTORAL Dominated by animals with no foliose algae but encrusting Rhodophycota patchy in grazed areas.
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 ZONES

(Definitions from Lincoln et al., 1998)

NERITIC Water column overlying the continental shelf; surface to ca 200m depth.
OCEANIC Open waters beyond the continental shelf.
EPIPELAGIC The photic zone, includes the open ocean influenced by light.  The lower boundary is dependant on the depth of light penetration and is generally regarded extend to ca 200 m in depth.
MESOPELAGIC The upper aphotic zone and extends to a depth of ca 1000 m.
BATHYLPELAGIC Extends from ca 1000 -2500 m.
ABYSSOPELAGIC Overlays the plains of the major ocean basins with a lower boundary of ca 6000 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.

References