Population Density, Mean Weight, and the Nature of the "Thinning Line" in Semibalanus Balanoides (L.) (Cirripedia Thoracica)

• Published in: Crustaceana 1985-01, Vol.49 (1-3), p.215-218
• Main Author: Hogarth, P.J
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Demecology; Fundamental and applied biological sciences. Psychology; Marine; Notes and News; Plant growth; Plants; Population density; Semibalanus balanoides
• ISSN: 0011-216X; 1568-5403
• DOI: 10.1163/156854085X00495

In much of the intertidal zone, space suitable for attachment and growth of barnacles such as Semibalanus balanoides (L.) is severely limited and competition for available space correspondingly intense. The situation is analogous to that well-known in plants, where a quantitative relationship has been established between the populationdensity and the mean dry weight of individuals within a cohort. For a remarkably wide range of situations and of plant species, the "thinning line" is of the form: W sub(d) = kD super(-1.5) or log W super(b)- sub(d) = log k - 1.5 log D (where W super(b)- is the mean dry weight of a plant and D the population density of plants: the constant k reflects the units of measurement, and varies also between species.) From the consistency of the exponent, this has been described as the "-3/2 power law". To ascertain whether a similar quantitative relationship holds for intranspecifically competing barnacles, Semibalanus balanoides) was studied on the Isle of Cumbrae (Bute, Scotland) during early July 1983 and 1984.