Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support

Intraspecific Competition in Petella cochlear Born

G. M. Branch
Journal of Animal Ecology
Vol. 44, No. 1 (Feb., 1975), pp. 263-281
DOI: 10.2307/3862
Stable URL: http://www.jstor.org/stable/3862
Page Count: 20
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Intraspecific Competition in Petella cochlear
                            Born
Preview not available

Abstract

(1) The density of Patella cochlear varies from 90 to 1700/m2, and is correlated with wave action. Highest densities occur with moderate to strong wave action. (2) As density increases, mean and maximum sizes decrease, growth rate is lower, and mortality of juveniles is greater. The latter is partly because a greater proportion of juveniles occur on shells of other limpets, and mortality is high during their transition to a rocky substrate. (3) Standing crop increases with density until the latter reaches about 450/m2. Above this value, biomass remains static at about 125 gm/m2 despite further increases in density. (4) This suggests that competition is most intense above this density. (5) Density has no direct effect on gonad size, but at above 430/m2 gonad output per m2 decreases relative to density because mean size is reduced. (6) Low densities are associated with high gonad output, high densities with low output. This results in a negative feedback controlling overall numbers. (7) High-density populations remain high because of recruitment, settlement being highest where wave action is strong. (8) Intraspecific competition is slight at densities of less than 250/m2 and most intense over 450/m2. The median density at Dalebrook is 300-400/m2, but many populations have higher densities. (9) Densities of about 300/m2 are required to exclude other limpets and to prevent the foodplant lithothamnion from being overgrown by other algae. To maintain monopoly of the cochlear zone, high densities of P. cochlear are required. (10) Concomitantly intraspecific competition is high, but it is suggested that this is balanced against co-operation promoting exclusion of other limpets from the community and maintenance of the foodplant.

Page Thumbnails

  • Thumbnail: Page 
263
    263
  • Thumbnail: Page 
264
    264
  • Thumbnail: Page 
265
    265
  • Thumbnail: Page 
266
    266
  • Thumbnail: Page 
267
    267
  • Thumbnail: Page 
268
    268
  • Thumbnail: Page 
269
    269
  • Thumbnail: Page 
270
    270
  • Thumbnail: Page 
271
    271
  • Thumbnail: Page 
272
    272
  • Thumbnail: Page 
273
    273
  • Thumbnail: Page 
274
    274
  • Thumbnail: Page 
275
    275
  • Thumbnail: Page 
276
    276
  • Thumbnail: Page 
277
    277
  • Thumbnail: Page 
278
    278
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
279
    279
  • Thumbnail: Page 
280
    280
  • Thumbnail: Page 
281
    281