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Marine Biology

, Volume 139, Issue 3, pp 463–474 | Cite as

Ecology of subtropical hermit crabs in S.W. Madagascar: cluster structure and function

  •  D. Barnes
  •  R. Arnold

Abstract.

The Madagascar coast (both) has a higher density and diversity of hermit crabs than is known from any other locality in the western Indian Ocean. Of the 20 species occurring at Anakao (S.W. Madagascar), 11 aggregated into clusters, including all but one of the species above the subtidal zone. The mean number of hermit crabs and species in clusters varied with several spatial parameters and time. Over 80% of the community clustered in certain habitats in particular tidal zones, whilst as low as 3% clustered in others. The highest intensity of clustering with shore zone was coincident with peak numbers of hermit crabs. The initiation and duration of clusters of hermit crabs above the eulittoral was driven by circadian rhythms, whilst those in the eulittoral were governed by tidal state. Clusters above and below the eulittoral were longer in duration, and those in the subtidal were more temporally variable than those above it. Certain pairs of species showed positive correlations of occurrence and (more rarely) of abundance, and all the correlations (of occurrence) of one, Clibanarius eurysternus, were negative. Positive correlations of occurrence were related to the degree of shell-use commonality between species pairs. Eulittoral species clustered with other individuals of approximately similar size and exchanged shells upon cluster disintegration. There was evidence of a dehydration–reduction function to shell clustering in addition to shell-exchange facilitation. The highly variable species-specific strategies of clustering may be important in alleviating both intra- and interspecific competition in assemblages of similar and highly abundant species.

Keywords

High Intensity Dehydration Indian Ocean Circadian Rhythm Abundant Species 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  D. Barnes
    • 1
  •  R. Arnold
    • 2
  1. 1.Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Cork, Ireland
  2. 2.British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET, UK

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