Emergent spatial patterns can indicate upcoming regime shifts in a realistic model of coral community

This is the article Emergent spatial patterns can indicate upcoming regime shifts in a realistic model of coral community, by Alexandre Génin, Sergio A. Navarrete, Angeles Garcia-Mayor, and Evie A. Wieters.

Released with six months embargo period under Taverne amendment https://www.uu.nl/en/university-library/taverne

Full affiliations: 

Alexandre Génin*(1,2), Sergio A. Navarrete (2,3,4), Angeles Garcia-Mayor (1,5), Evie A. Wieters (2)

1 Copernicus Institute of Sustainable Development, Utrecht University, PO Box 80115, 3508 TC, Utrecht, The Netherlands.

2 Estación Costera de Investigaciones Marinas and Millenium Nucleus for Ecology and Conservation of Temperate Mesophotic, Reefs Ecosystems (NUTME), Pontificia Universidad Católica de Chile, Las Cruces, Chile.

3 Center for Applied Ecology and Sustainability (CAPES) and Coastal Socio-Ecological Millenium Institute (SECOS), Pontificia Universidad Católica de Chile

4 Centro Basal COPAS COASTAL, Universidad de Concepción

5 Biodiversity, Ecology and Evolution Dept., Complutense University of Madrid, Spain

* Corresponding author: a.a.h.genin@uu.nl

Abstract: 

Increased stress on coastal ecosystems, such as coral reefs, seagrasses, kelp forests and other habitats can make them shift towards degraded, often algae-dominated or barren communities. This has already occurred in many places around the world, calling for new approaches to identify where such regime shifts may be triggered. Theoretical work predicts that the spatial structure of habitat-forming species should exhibit changes prior to regime shifts, such as an increase in spatial autocorrelation. However, extending this theory to marine systems requires theoretical models connecting field-supported ecological mechanisms to data and spatial patterns at relevant scales. To do so, we built a spatially-explicit model of sub-tropical coral communities based on experiments and long-term datasets from Rapa Nui (Easter Island, Chile), to test whether spatial indicators could signal upcoming regime shifts in coral communities. Spatial indicators anticipated degradation of coral communities following increases in frequency of bleaching events or coral mortality. However, they were generally unable to signal shifts that followed herbivore loss, a widespread and well-researched source of degradation, likely because herbivory, despite being critical for the maintenance of corals, had comparatively little effect on their self-organization. Informative trends were found both under equilibrium and non-equilibrium conditions, but were determined by the type of direct neighbor interactions between corals, which remain relatively poorly documented. These inconsistencies show that while this approach is promising, its application to marine systems will require detailed information about the type of stressor, and filling current gaps in our knowledge of interactions at play in coral communities.