Behavioural interactions between ecosystem engineers control community species richness

• Published in: Ecology letters Vol. 12; no. 11; pp. 1127 - 1136
• Main Authors: Gribben, Paul E, Byers, James E, Clements, Michael, McKenzie, Louise A, Steinberg, Peter D, Wright, Jeffrey T
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.11.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Algae; Anadara; Anadara trapezia; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Arcidae - physiology; Australia; behavior; Behavior, Animal; Behaviour; Biodiversity; Biological and medical sciences; bivalves; Bivalvia; Caulerpa; Caulerpa - physiology; Caulerpa taxifolia; Ecology; ecosystem engineer; epibiota; facilitation cascades; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments; habitat-forming species; invasive species; Invertebrates; Marine biology; Mollusca; Mollusks; Nonnative species; Population Dynamics; recruitment; trait-mediated indirect effects; Australia; Facilitation; facilitation cascades; trait-mediated indirect effects; Behaviour; epibiota; Interaction; habitat-forming species; bivalves; Recruitment; Invasive species; Bivalvia; Habitat; Behavior; Invertebrata; Mollusca; Community; Species richness; Ecosystem engineer
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/j.1461-0248.2009.01366.x

Behavioural interactions between ecosystem engineers may strongly influence community structure. We tested whether an invasive ecosystem engineer, the alga Caulerpa taxifolia, indirectly facilitated community diversity by modifying the behaviour of a native ecosystem engineer, the clam Anadara trapezia, in southeastern Australia. In this study, clams in Caulerpa-invaded sediments partially unburied themselves, extending >30% of their shell surface above the sediment, providing rare, hard substrata for colonization. Consequently, clams in Caulerpa had significantly higher diversity and abundance of epibiota compared with clams in unvegetated sediments. To isolate the role of clam burial depth from direct habitat influences or differential predation by habitat, we manipulated clam burial depth, predator exposure and habitat (Caulerpa or unvegetated) in an orthogonal experiment. Burial depth overwhelmingly influenced epibiont species richness and abundance, resulting in a behaviourally mediated facilitation cascade. That Caulerpa controls epibiont communities by altering Anadara burial depths illustrates that even subtle behavioural responses of one ecosystem engineer to another can drive extensive community-wide facilitation.