Terms used for field recording and habitat definition

For semi-quantitative biological recording, the MNCR SACFOR scale was used.
The following definitions for physical habitat characteristics are taken from guidance notes for MNCR field recording (Appendix 8 in Hiscock ed. 1996). Some terms are modified for use in the classification.
 
Salinity - The categories are defined as follows (the points of separation approximate to critical tolerance limits for marine species):
 
Fully marine
30-40 ‰
Variable
18-40 ‰
Reduced
18-30 ‰
Low
<18 ‰
 
Wave exposure - These categories take account of the aspect of the coast (related to direction of prevailing or strong winds), the fetch (distance to nearest land), its openness (the degree of open water offshore) and its profile (the depth profile of water adjacent to the coast). Estimation of wave exposure requires inspection of charts and maps.
 
Extremely exposed
This category is for the few open coastlines which face into prevailing wind and receive oceanic swell without any offshore breaks (such as islands or shallows) for several thousand km and where deep water is close to the shore (50 m depth contour within about 300 m, e.g. Rockall).
Very exposed
These are open coasts which face into prevailing winds and receive oceanic swell without any offshore breaks (such as islands or shallows) for several hundred km but where deep water is not close (>300 m) to the shore. They can be adjacent to extremely exposed sites but face away from prevailing winds (here swell and wave action will refract towards these shores) or where, although facing away from prevailing winds, strong winds and swell often occur (for instance, the east coast of Fair Isle).
Exposed
At these sites, prevailing wind is onshore although there is a degree of shelter because of extensive shallow areas offshore, offshore obstructions, a restricted (<90o) window to open water. These sites will not generally be exposed to strong or regular swell. This can also include open coasts facing away from prevailing winds but where strong winds with a long fetch are frequent.
Moderately exposed
These sites generally include open coasts facing away from prevailing winds and without a long fetch but where strong winds can be frequent.
Sheltered
At these sites, there is a restricted fetch and/or open water window. Coasts can face prevailing winds but with a short fetch (say <20 km) or extensive shallow areas offshore or may face away from prevailing winds.
Very sheltered
These sites are unlikely to have a fetch greater than 20 km (the exception being through a narrow (<30o) open water window, they face away from prevailing winds or have obstructions, such as reefs, offshore.
Extremely sheltered
These sites are fully enclosed with fetch no greater than about 3 km.
Ultra sheltered
Sites with fetch of a few tens or at most 100s of metres.
 
In the habitat classification exposed (as in exposed littoral rock) encompasses the extremely exposed, very exposed and exposed categories, whilst sheltered (as in sheltered littoral rock) encompasses sheltered to ultra sheltered categories.
 
Tidal currents (or streams) (maximum at surface) - This is maximum tidal current strength which affects the actual area surveyed. Note for shores and inshore areas this may differ considerably from the tidal currents present offshore. In some narrows and sounds the top of the shore may only be covered at slack water, but the lower shore is subject to fast running water.
 
Very strong
>6 knots            (>3 m/sec.)
Strong
3-6 knots           (>1.5-3 m/sec.)
Moderately strong
1-3 knots           (0.5-1.5 m/sec.)
Weak
<1 knot             (<0.5 m/sec.)
Very weak
Negligible
 
In the habitat classification tide-swept habitats typically have moderately strong or stronger tidal currents.
 
Zone - These definitions primarily relate to rocky habitats or those where algae grow (e.g. stable shallow sublittoral sediments). For use of the terms infralittoral and circalittoral in the classification, especially for sediments, refer also to Table 5.
 
Supralittoral
Colonised by yellow and grey lichens, above the Littorina populations but generally below flowering plants.
Upper littoral fringe
This is the splash zone above High Water of Spring Tides with a dense band of the black lichen by Verrucaria maura. Littorina saxatilis and Littorina neritoides often present. May include saltmarsh species on shale/pebbles in shelter.
Lower littoral fringe
The Pelvetia (in shelter) or Porphyra (exposed) belt. With patchy Verrucaria maura, Verrucaria mucosa and Lichina pygmaea present above the main barnacle population. May also include saltmarsh species on shale/pebbles in shelter.
Upper eulittoral
Barnacles and limpets present in quantity or with dense Fucus spiralis in sheltered locations.
Mid eulittoral
Barnacle-limpet dominated, sometimes mussels or dominated by Fucus vesiculosus and Ascophyllum nodosum in sheltered locations. Mastocarpus stellatus and Palmaria palmata patchy in lower part. Usually quite a wide belt.
Lower eulittoral
Fucus serratus, Mastocarpus stellatus, Himanthalia elongata or Palmaria palmata variously dominant; barnacles sparse.
Sublittoral fringe
Dominated by Alaria esculenta (very exposed), Laminaria digitata (exposed to sheltered) or Laminaria saccharina (very sheltered) with encrusting coralline algae; barnacles sparse.
Upper infralittoral
Dense forest of kelp.
Lower infralittoral
Sparse kelp park, dominated by foliose algae except where grazed. May lack kelp.
Upper circalittoral
Dominated by animals, lacking kelp but with sparse foliose algae except where grazed.
Lower circalittoral
Dominated by animals with no foliose algae but encrusting coralline algae.
 
Substratum
 
Bedrock
Includes very soft rock-types such as chalk, peat and clay.
Boulders
Very large (>1024 mm), large (512-1024 mm), small (256-512 mm)
Cobbles
64-256 mm
Pebbles
16-64 mm
Gravel
4-16 mm
Coarse sand
1-4 mm
Medium sand
0.25-1 mm
Fine sand
0.063 - 0.25 mm
Mud
<0.063 mm (the silt/clay fraction)
 
Each division of sediment type above represents two divisions on the Wentworth scale (Wentworth 1922).
 
In the habitat classification, bedrock, stable boulders, cobbles or pebbles and habitats of mixed boulder, cobble, pebble and sediment (mixed substrata) as well as artificial substrata (concrete, wood, metal) are collectively referred to as rock. Highly mobile cobbles and pebbles (shingle), together with gravel and coarse sand are collectively referred to as coarse sediments. Mixed sediment consists of heterogeneous mixtures of gravel, sand and mud and may often have shells and stones also.