An empirical examination of consumer effects across twenty degrees of latitude

James T. Lavender, Katherine A. Dafforn, Melanie J. Bishop, Emma L. Johnston

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The strength and importance of consumer effects are predicted to increase toward low latitudes, but this hypothesis has rarely been tested using a spatially consistent methodology. In a consumer-exclusion experiment spanning twenty degrees of latitude along the east Australian coast, the magnitude of consumer effects on sub-tidal sessile assemblage composition was not greater at low than high latitudes. Across caged and control assemblages, Shannon's diversity, Pielou's evenness, and richness of functional groups decreased with increasing latitude, but the magnitude of consumer effects on these metrics did not display consistent latitudinal gradients. Instead, latitudinal gradients in consumer effects were apparent for individual functional groups. Solitary ascidians displayed the pattern consistent with predictions of greater direct effects of predators at low than high latitude. As consumers reduced the biomass of this and other competitive dominants, groups less prone to predation (e.g., hydroids, various groups of bryozoans) were able to take advantage of freed space in the presence of consumers and show increased abundances there. This large-scale empirical study demonstrates the complexity of species interactions, and the failure of assemblage-level metrics to adequately capture consumer effects over large spatial gradients.

LanguageEnglish
Pages2391-2400
Number of pages10
JournalEcology
Volume98
Issue number9
DOIs
Publication statusPublished - Sep 2017

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latitudinal gradient
functional group
Bryozoa
exclusion experiment
Ascidiacea
effect
predation
predators
coasts
prediction
predator
biomass
methodology
coast

Bibliographical note

Copyright by the Ecological Society of America. Article published in Ecology (2017), Vol. 98, Issue. 9, pp. 2391–2400 by Lavender, J. T., Dafforn, K. A., Bishop, M. J., & Johnston, E. L.

Keywords

  • assemblages
  • biotic interactions hypothesis
  • consumers
  • interaction strength
  • latitudinal gradient
  • multivariate

Cite this

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An empirical examination of consumer effects across twenty degrees of latitude. / Lavender, James T.; Dafforn, Katherine A.; Bishop, Melanie J.; Johnston, Emma L.

In: Ecology, Vol. 98, No. 9, 09.2017, p. 2391-2400.

Research output: Contribution to journalArticleResearchpeer-review

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