Post-Disturbance Stability of Fish Assemblages Measured at Coarse Taxonomic Resolution Masks Change at Finer Scales

PLoS One. 2016 Jun 10;11(6):e0156232. doi: 10.1371/journal.pone.0156232. eCollection 2016.

Abstract

Quantifying changes to coral reef fish assemblages in the wake of cyclonic disturbances is challenging due to spatial variability of damage inherent in such events. Often, fish abundance appears stable at one spatial scale (e.g. reef-wide), but exhibits substantial change at finer scales (e.g. site-specific decline or increase). Taxonomic resolution also plays a role; overall stability at coarse taxonomic levels (e.g. family) may mask species-level turnover. Here we document changes to reef fish communities after severe Tropical Cyclone Ita crossed Lizard Island, Great Barrier Reef. Coral and reef fish surveys were conducted concurrently before and after the cyclone at four levels of exposure to the prevailing weather. Coral cover declined across all exposures except sheltered sites, with the largest decline at exposed sites. There was no significant overall reduction in the total density, biomass and species richness of reef fishes between 2011 and 2015, but individual fish taxa (families and species) changed in complex and unpredictable ways. For example, more families increased in density and biomass than decreased following Cyclone Ita, particularly at exposed sites whilst more fish families declined at lagoon sites even though coral cover did not decline. All sites lost biomass of several damselfish species, and at most sites there was an increase in macroinvertivores and grazers. Overall, these results suggest that the degree of change measured at coarse taxonomic levels masked high species-level turnover, although other potential explanations include that there was no impact of the storm, fish assemblages were impacted but underwent rapid recovery or that there is a time lag before the full impacts become apparent. This study confirms that in high-complexity, high diversity ecosystems such as coral reefs, species level analyses are essential to adequately capture the consequences of disturbance events.

MeSH terms

  • Animals
  • Anthozoa / classification
  • Bias
  • Biodiversity*
  • Classification / methods*
  • Conservation of Natural Resources / methods*
  • Coral Reefs
  • Cyclonic Storms* / statistics & numerical data
  • Ecosystem*
  • Fishes / classification*
  • Meteorological Concepts
  • Population Density

Grants and funding

The 2015 study was undertaken with support from the John and Laurie Proud Foundation, the Hermon Slade Raiatea Foundation and Isobel Bennett Fellowships awarded to DMC and ZTR. The 2011 study was supported and funded from a research grant by the Australian Museum to ZTR. The funders provided support in the form of salaries for authors (Z. Richards in 2011, Z. Richards and D. Ceccarelli in 2015), but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.