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Balanus balanoides, the barnacle, Ballantine's main indicator of a medium exposure in the mid-littoral zone.

The Ballantine Scale is a biologically defined scale for measuring the degree of exposure of rocky shores to wave action. Devised in 1961 by W. J. Ballantine, then at the zoology department of Queen Mary College, London, the scale is based on the observation that where shoreline species are concerned "Different species growing on rocky shores require different degrees of protection from certain aspects of the physical environment, of which wave action is often the most important." The species present in the littoral zone therefore indicate the degree of the shore's exposure.[1]

Contents

Abbreviated summary

An abbreviated summary of the scale is given below. The scale runs from 1) an "extremely exposed" shore, to 8) an "extremely sheltered" shore. The littoral zone generally is the zone between low and high tides. The supra-littoral is above the barnacle line.

Scale
unit
Name Environment Species
1 Extremely exposed Continuous heavy surf Infra-littoral: Alaria dominant;
Mid-littoral:Himanthalia, Gigurtina, Chthalamus dominant
Supra-littoral: dense Porphyra, lichens abundant
2 Very exposed "Workable only on calm days" Infra-littoral: Alaria less frequent to common, Laminaria digitata dominant
Mid-littoral: scattered Himanthalia, Gigurtina; Chthalamus abundant and dominant; Balanus balanoides frequent to common
Supra-littoral: scattered Porphyra
3 Exposed Occasional full Atlantic storm-waves Infra-littoral: Laminaria dominant
Mid-littoral: Balanus balanoides dominant on lower half; Chthalamus on upper with Patella aspera; Patella vulgata abundant over whole
Supra-littoral: top shells absent. Nucella on upper rock, Mytilus in crevices
4 Semi-exposed Obvious "reduction in wave action" Infra-littoral: Laminaria abundant
Mid-littoral: Chthalamus, Balanus Fucus serratus, Patella vulgata common
Supra-littoral: occasional Gibbula umbiliacus, Nucella on open rock

Modifications to the scale

A modified exposure scale of five stages applying to the shores of the British Isles is given by Lewis (1964):[2]

  1. Very Exposed Shores have a wide Verrucaria zone entirely above the upper tide level, a Porphyra zone above the barnacle level and Lichina pygmaea is locally abundant. The eulittoral zone is dominated by barnacles and limpets with a coralline belt in the very low littoral along with other Rhodophyta and Alaria in the upper sublittoral.
  2. Exposed Shores show a Verrucaria belt mainly above the high tide, with Porphyra and Lichina pygmaea. The mid shore is dominated by barnacles, limpets and some Fucus. Some Rhodophyta. Himanthalia and some Rhodophyta such as Mastocarpus and Corallina are found in the low littorral with Himanthalia, Alaria and Laminaria digitata dominant in the upper sublittoral.
  3. Semi-exposed Shores show a Verrucaria belt just above high tide with clear Pelvetia in the upper-littoral and Fucus serratus in the lower-littoral. Limpets, barnacles and short Fucus vesiculosus midshore. Fucus serratus with Rhodophyta, (Laurencia, Mastocarpus stellatus, Rhodymenia and Lomentaria). Laminaria and Saccorhiza polyschides and small algae common in the sublittoral.
  4. Sheltered Shores show a narrow Verrucaria zone at high water and a full sequence of fucoids: Pelvetia, Fucus spiralis, Fucus vesiculosus, Fucus serratus, Ascophyllum nodosum. Laminaria digitata is dominant the upper sublittoral.
  5. Very Sheltered Shores show a very narrow zone of Verrucaria, the dominance of the littoral by a full sequence of the fucoids and Ascophyllum covering the rocks. Laminaria saccharina, Halidrys, Chondrus and or Furcellaria.

Notes

  1. ^ Ballantine (1961) page 1.
  2. ^ Lewis, J R (1964). The Ecology of Rocky Shores. London: The English Universities Press.  

References

Ballantine, W.J. (1961). "A Biologically-defined Exposure Scale for the Comparative Description of Rocky Shores" (pdf). Field Studies Journal 1 (3). http://www.field-studies-council.org/fieldstudies/documents/vol1.3_17.pdf. Retrieved 2008-12-17.  

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