The Ballantine Scale is a biologically defined scale for measuring the degree of exposure level of wave action on a rocky shore. 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]
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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 |
A modified exposure scale of five stages applying to the shores of the British Isles is given by Lewis (1964):[2]
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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