Behavioral self-organization underlies the resilience of a coastal ecosystem

Johan Van De Koppel,Brian R Silliman,Aniek Van Den Berg,Hélène De Paoli,Peter M J Herman,Tjisse Van Der Heide

doi:10.1073/pnas.1619203114

Abstract

Self-organized spatial patterns occur in many terrestrial, aquatic, and marine ecosystems. Theoretical models and observational studies suggest self-organization, the formation of patterns due to ecological interactions, is critical for enhanced ecosystem resilience. However, experimental tests of this cross-ecosystem theory are lacking. In this study, we experimentally test the hypothesis that self-organized pattern formation improves the persistence of mussel beds (Mytilus edulis) on intertidal flats. In natural beds, mussels generate self-organized patterns at two different spatial scales: regularly spaced clusters of mussels at centimeter scale driven by behavioral aggregation and large-scale, regularly spaced bands at meter scale driven by ecological feedback mechanisms. To test for the relative importance of these two spatial scales of self-organization on mussel bed persistence, we conducted field manipulations in which we factorially constructed small-scale and/or large-scale patterns. Our results revealed that both forms of self-organization enhanced the persistence of the constructed mussel beds in comparison to nonorganized beds. Small-scale, behaviorally driven cluster patterns were found to be crucial for persistence, and thus resistance to wave disturbance, whereas large-scale, self-organized patterns facilitated reformation of small-scale patterns if mussels were dislodged. This study provides experimental evidence that self-organization can be paramount to enhancing ecosystem persistence. We conclude that ecosystems with self-organized spatial patterns are likely to benefit greatly from conservation and restoration actions that use the emergent effects of self-organization to increase ecosystem resistance to disturbance.

Highlights

Self-organized spatial patterns occur in many terrestrial, aquatic, and marine ecosystems
Theoretical studies have highlighted that local ecological interactions can explain the formation of large-scale spatial patterns through a process called spatial self-organization [9, 11, 12] (Fig. 1)
Despite well-developed theory predicting that self-organization can enhance ecosystem resistance to disturbance, there is currently no experimental evidence supporting this idea in any real-world situation

Summary

Introduction

Self-organized spatial patterns occur in many terrestrial, aquatic, and marine ecosystems. Theoretical studies have highlighted that local ecological interactions can explain the formation of large-scale spatial patterns through a process called spatial self-organization [9, 11, 12] (Fig. 1). Spartina alterniflora propagules are typically planted at a constant and dispersed distance in salt marsh restoration projects, eliminating facilitation between out-plants and reducing overall yield [24, 25] To advance both fundamental and conservation science regarding selforganization, there is an urgent need for experimental tests of the emergent effects of spatial self-organization on ecosystem stability and persistence, using manipulative techniques. Theoretical models suggest that spatial self-organization enhances the resistance of ecosystems to disturbance Experiments investigating this important prediction are lacking. Our study emphasizes the potential of harnessing spatial self-organization to enhance restoration success and persistence of threatened ecosystems

Methods

Results

Conclusion