Coral Reefs

, Volume 31, Issue 2, pp 461–469 | Cite as

Epibiotic mutualists alter coral susceptibility and response to biotic disturbance through cascading trait-mediated indirect interactions



Biotic disturbances are important drivers of community structure, but interactions among community members can determine trajectories of response and recovery. On coral reefs in French Polynesia, epibiotic amphipods induce the formation of branch-like “fingers” on flat colonies of encrusting Montipora coral. The fingers form as coral encrusts the amphipods’ tubes and lead to significant changes in colony morphology. I tested whether the induced morphological changes affect Montipora’s susceptibility to predation by pincushion (Culcita novaeguineae) and crown-of-thorns sea stars (Acanthaster planci). Montipora with fingers were less likely to be attacked and more likely to survive attack than colonies without fingers. Furthermore, the presence of fingers altered A. planci prey preference. Sea stars preferred Montipora without fingers over other common coral genera, but preferred other genera when Montipora had fingers. Amphipods indirectly affected Montipora’s resistance and resilience to predation, and the susceptibility of other coral genera to predation, through induced morphological changes. Such trait-mediated indirect interactions likely play an important role in determining how species respond to periodic sea star outbreaks.


Trait-mediated indirect interaction (TMII) Disturbance Mutualism Coral morphology Acanthaster planci Montipora 

Supplementary material

338_2011_861_MOESM1_ESM.doc (32 kb)
Supplementary material 1 (DOC 32 kb)
338_2011_861_MOESM2_ESM.tif (11.1 mb)
Plate S1: (a) Amphipod-induced finger structures extend from an encrusting Montipora colony. Colonies with fingers exhibited morphologies resembling those of branching corals. (b) A colony of Acropora digitifera used in a feeding trial. Pairs of corals were presented to predators on cinder blocks, so that a sea star feeding on one coral in the pair could easily detect the other. The Acanthaster planci pictured is feeding on a Montipora sp. without fingers that had been paired with the A. digitifera. (c) The feeding scar left by a pin-cushion star (Culcita novaguineae) on a Montipora colony during a feeding trial. The C. novaguineae consumed plating coral along the colony’s edge, but stopped when it encountered finger structures (indicated by arrows). (d) Feeding scar left by a crown-of-thorns sea star (Acanthaster planci) on a Montipora sp. colony in the wild. The A. planci (bottom right) fed on encrusting Montipora until it encountered finger structures (top center) and a Porites sp. colony (top left), then retreated (TIFF 11413 kb)


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Department of Ecology, Evolution and Marine BiologyUniversity of CaliforniaSanta BarbaraUSA
  2. 2.Division of Science and Environmental PolicyCalifornia State University Monterey BaySeasideUSA

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