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 Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Resource Utilization by Gammarus pulex (Amphipoda) in a Cotswold Stream: A Microdistribution Study

John H. R. Gee
Journal of Animal Ecology
Vol. 51, No. 3 (Oct., 1982), pp. 817-831
DOI: 10.2307/4007
Stable URL: http://www.jstor.org/stable/4007
Page Count: 15
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Resource Utilization by Gammarus pulex (Amphipoda) in a Cotswold Stream: A Microdistribution Study
Preview not available

Abstract

(1) Multiple linear regression was used to relate the numbers of the amphipod Gammarus pulex (L.) to the organic and physical characteristics of the stream substratum. Different size classes were treated separately. (2) Substratum particle size and the amount of detritus were recorded both by gravimetric methods and by analysis of photographs of the substratum surface. These methods gave quite different results, particularly if a layer of silt was present on the substratum surface. Information derived from substratum photography was the more effective in explaining microdistribution patterns. (3) G. pulex larger than 6 mm (body length) appeared to congregate in places where there were accumulations (packets) of autumn-shed leaves, but only if these were visible on the substratum surface. Smaller individuals showed no clear relationship with detrital distribution. (4) Leaf packets containing species that decayed rapidly were selected for by large G. pulex early in the autumn. Later, only resistant species were available and leaf species did not appear to influence microdistribution. (5) There was a relationship between substratum particle size and the size of G. pulex. Larger individuals were found in progressively narrower ranges of larger particle sizes. It is suggested that the size of interstices between particles controls the sizes of animals that may colonize an area. (6) In experiments in an artificial stream, the rates of movement of all sizes of G. pulex were inversely related to substratum particle size, but the difference between rates of movement over fine and coarse substrata was greatest for large individuals. This result corroborates the relationship between particle size and body size that was observed in the field.

Page Thumbnails

  • Thumbnail: Page 
817
    817
  • Thumbnail: Page 
818
    818
  • Thumbnail: Page 
819
    819
  • Thumbnail: Page 
820
    820
  • Thumbnail: Page 
821
    821
  • Thumbnail: Page 
822
    822
  • Thumbnail: Page 
823
    823
  • Thumbnail: Page 
824
    824
  • Thumbnail: Page 
825
    825
  • Thumbnail: Page 
826
    826
  • Thumbnail: Page 
827
    827
  • Thumbnail: Page 
828
    828
  • Thumbnail: Page 
829
    829
  • Thumbnail: Page 
830
    830
  • Thumbnail: Page 
831
    831