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# Sublittoral Seaweed Survey of the Orkney Islands

F. T. Walker
Journal of Ecology
Vol. 38, No. 1 (Jul., 1950), pp. 139-165
DOI: 10.2307/2256528
Stable URL: http://www.jstor.org/stable/2256528
Page Count: 27
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## Abstract

Further sublittoral seaweed surveys have been carried out around the islands of Orkney, north of the mainland of Scotland. Analyses of the data gave the following quantities: In all seven areas the average seaweed density is related to the seaweed cover and the depth, according to the formula $\sqrt d/C = k - \gamma f$, where d = average fresh weight found in sampling operations at a particular depth C = percentage seaweed cover at the corresponding depth and f = depth. The factors of k and γ vary with each survey area but can be correlated with the rate of tidal streams occurring during spring tides. The absorption by seawater of light in the region of 6600 A, appears to be a limiting factor to seaweed density with increasing depth.

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