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 and Facilitation in a Northern Acorn Barnacle Population

Mark D. Bertness
Ecology
Vol. 70, No. 1 (Feb., 1989), pp. 257-268
Published by: Wiley
DOI: 10.2307/1938431
Stable URL: http://www.jstor.org/stable/1938431
Page Count: 12
  • Download ($42.00)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Intraspecific Competition and Facilitation in a Northern Acorn Barnacle Population
Preview not available

Abstract

The role of density-dependent mortality in shaping adult populations of the acorn barnacle, Semibalanus balanoides, was studied on a sheltered New England shore and revealed that high recruitment densities can have both positive and negative effects on barnacle survival. Recruitment greatly exceeded the capacity of the space to support adults in the three years of this study. At low tidal heights, recruits grew rapidly, experienced severe crowding, and rarely survived to reproduce. At higher tidal heights, individuals grew more slowly and were less affected by crowding, and many (@?10%) survived to reproduce. Recruit density was manipulated to examine crowding effects on survival. At low tidal heights, no recruits survived to reproduce at any density, due to intraspecific crowding, algal overgrowth, and predation. At intermediate tidal heights, lower recruitment decreased intraspecific crowding and increased survivorship, while at high tidal heights, lower recruitment decreased survivorship. In the high intertidal habitat, S. balanoides survivorship was higher on boulders than on rock cobbles due to thermal buffering, and intraspecific crowding decreased rock and barnacle temperatures and facilitated survival. Shading high intertidal cobbles from solar radiation decreased maximum rock and barnacle temperatures, dramatically increased survivorship and eliminated the survivorship advantage of high densities. High recruitment of S. balanoides can lead to massive density-dependent mortality in physically benign habitats, but in physically stressful habitats high recruitment density may buffer individuals from physical stress and facilitate survival. Variation in the nature of density-dependent interactions along environmental gradients may be important in generating pattern in many natural populations.

Page Thumbnails

  • Thumbnail: Page 
257
    257
  • Thumbnail: Page 
258
    258
  • Thumbnail: Page 
259
    259
  • Thumbnail: Page 
260
    260
  • Thumbnail: Page 
261
    261
  • Thumbnail: Page 
262
    262
  • Thumbnail: Page 
263
    263
  • Thumbnail: Page 
264
    264
  • Thumbnail: Page 
265
    265
  • Thumbnail: Page 
266
    266
  • Thumbnail: Page 
267
    267
  • Thumbnail: Page 
268
    268