Trophic cascade induced by molluscivore predator alters pore-water biogeochemistry via competitive release of prey

Jan A. Van Gils, Matthijs Van Der Geest*, Erik J. Jansen, Laura L. Govers, Jimmy De Fouw, Theunis Piersma

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

32 Citations (Scopus)


Effects of predation may cascade down the food web. By alleviating interspecific competition among prey, predators may promote biodiversity, but the precise mechanisms of how predators alter competition have remained elusive. Here we report on a predator-exclosure experiment carried out in a tropical intertidal ecosystem, providing evidence for a three-level trophic cascade induced by predation by molluscivore Red Knots (Calidris canutus) that affects pore water biogeochemistry. In the exclosures the knots' favorite prey (Dosinia isocardia) became dominant and reduced the individual growth rate in an alternative prey (Loripes lucinalis). Dosinia, a suspension feeder, consumes suspended particulate organic matter (POM), whereas Loripes is a facultative mixotroph, partly living on metabolites produced by sulfur-oxidizing chemoautotrophic bacteria, but also consuming suspended POM. Reduced sulfide concentrations in the exclosures suggest that, without predation on Dosinia, stronger competition for suspended POM forces Loripes to rely on energy produced by endosymbiotic bacteria, thus leading to an enhanced uptake of sulfide from the surrounding pore water. As sulfide is toxic to most organisms, this competitioninduced diet shift by Loripes may detoxify the environment, which in turn may facilitate other species. The inference that predators affect the toxicity of their environment via a multi-level trophic cascade is novel, but we believe it may be a general phenomenon in detritus-based ecosystems.

Original languageEnglish
Pages (from-to)1143-1152
Number of pages10
Issue number5
Publication statusPublished - May 2012
Externally publishedYes


  • Banc d'Arguin, mauritania
  • Bivalves (Dosinia isocardia, loripes lucinalis)
  • Facilitation
  • Growth rate
  • Hydrogen sulfide
  • Interspecific competition
  • Predation
  • Predator-exclosure experiment
  • Red Knot, Calidris canutus canutus
  • Seagrass beds
  • Top-down effect


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