title: Species fluctuations sustained by a cyclic succession at the edge of chaos.
abstract: Although mathematical models and laboratory experiments have shown that species interactions can generate chaos, field evidence of chaos in natural ecosystems is rare. We report on a pristine rocky intertidal community located in one of the world's oldest marine reserves that has displayed a complex cyclic succession for more than 20 y. Bare rock was colonized by barnacles and crustose algae, they were overgrown by mussels, and the subsequent detachment of the mussels returned bare rock again. These processes generated irregular species fluctuations, such that the species coexisted over many generations without ever approaching a stable equilibrium state. Analysis of the species fluctuations revealed a dominant periodicity of about 2 y, a global Lyapunov exponent statistically indistinguishable from zero, and local Lyapunov exponents that alternated systematically between negative and positive values. This pattern indicates that the community moved back and forth between stabilizing and chaotic dynamics during the cyclic succession. The results are supported by a patch-occupancy model predicting similar patterns when the species interactions were exposed to seasonal variation. Our findings show that natural ecosystems can sustain continued changes in species abundances and that seasonal forcing may push these nonequilibrium dynamics to the edge of chaos.
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
authors.forename: Elisa
authors.initials: E
authors.lastname: Benincà
authors.affiliation: Leigh Marine Laboratory, University of Auckland, Warkworth, Northland 0941, New Zealand; and.
authors.forename: Bill
authors.initials: B
authors.lastname: Ballantine
authors.affiliation: Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Ellner
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands; j.huisman@uva.nl.
authors.forename: Jef
authors.initials: J
authors.lastname: Huisman
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D017753:Ecosystem; D008954:Models, Biological; D009520:New Zealand; D017711:Nonlinear Dynamics; D000459:Phaeophyceae / Q000502:physiology*; D011157:Population Dynamics / Q000706:statistics & numerical data; D012621:Seasons; D013045:Species Specificity; D001468:Thoracica / Q000502:physiology*; D013997:Time Factors
keywords: chaos; coexistence; cyclic succession; rocky intertidal community; rock–paper–scissors dynamics