Understanding the Spatio-Temporal Response of Coral Reef Fish Communities to Natural Disturbances: Insights from Beta-Diversity Decomposition

PLoS One. 2015 Sep 22;10(9):e0138696. doi: 10.1371/journal.pone.0138696. eCollection 2015.

Abstract

Understanding how communities respond to natural disturbances is fundamental to assess the mechanisms of ecosystem resistance and resilience. However, ecosystem responses to natural disturbances are rarely monitored both through space and time, while the factors promoting ecosystem stability act at various temporal and spatial scales. Hence, assessing both the spatial and temporal variations in species composition is important to comprehensively explore the effects of natural disturbances. Here, we suggest a framework to better scrutinize the mechanisms underlying community responses to disturbances through both time and space. Our analytical approach is based on beta diversity decomposition into two components, replacement and biomass difference. We illustrate this approach using a 9-year monitoring of coral reef fish communities off Moorea Island (French Polynesia), which encompassed two severe natural disturbances: a crown-of-thorns starfish outbreak and a hurricane. These disturbances triggered a fast logistic decline in coral cover, which suffered a 90% decrease on all reefs. However, we found that the coral reef fish composition remained largely stable through time and space whereas compensatory changes in biomass among species were responsible for most of the temporal fluctuations, as outlined by the overall high contribution of the replacement component to total beta diversity. This suggests that, despite the severity of the two disturbances, fish communities exhibited high resistance and the ability to reorganize their compositions to maintain the same level of total community biomass as before the disturbances. We further investigated the spatial congruence of this pattern and showed that temporal dynamics involved different species across sites; yet, herbivores controlling the proliferation of algae that compete with coral communities were consistently favored. These results suggest that compensatory changes in biomass among species and spatial heterogeneity in species responses can provide further insurance against natural disturbances in coral reef ecosystems by promoting high levels of key species (herbivores). They can also allow the ecosystem to recover more quickly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Anthozoa / physiology*
  • Biomass
  • Conservation of Natural Resources / methods
  • Coral Reefs*
  • Cyclonic Storms
  • Ecosystem*
  • Fishes / classification
  • Fishes / physiology*
  • Geography
  • Models, Theoretical
  • Polynesia
  • Population Density
  • Population Dynamics
  • Species Specificity
  • Starfish / physiology
  • Time Factors

Grants and funding

T. Lamy was supported by a post-doctoral fellowship from Laboratoire d'Excellence CORAIL to J. Claudet and by a postdoctoral scholarship from NSERC grant no. 7738 to P. Legendre. J. Claudet thanks Fondation de France—INTHENSE, ANR—LIVE AND LET DIE and ANR—ACRoSS for financial support. The authors also thank the Direction des Ressources Marines et Minières (DDRM) of French Polynesia for the financial support they provided for field surveys.