Kerry, J. T., Bellwood, D. R.

Competition for shelter in a high-diversity system: Structure use by large reef fishes

2015

Coral Reefs

34

1-8

"Competition among large reef fishes for shelter beneath tabular structures provides a rare opportunity to study competition in a species-rich environment. The system permits a detailed study of localized competition with major implications for coral reefs with respect to human impacts including climate change. Using underwater video cameras, this study examined competition among 30 species of large reef fishes (from nine families) for access to shelter provided by 26 tabular structures, which may be the highest reported diversity of vertebrates competing for a single resource. Mean concentrations of fishes under tabular structures were also among the highest biomass recorded on reefs (4.71 kg m-2). A generated dominance hierarchy for the occupation of shelter appeared to be primarily driven by the size of fishes. In contrast to previous studies, fishes higher in the hierarchy tended to exhibit the lowest levels of aggression. However, size difference between fishes was found to be strongly negatively correlated with the proportion of aggressive interactions (R 2 = 0.971, P less than 0.0001). The strong competition for the shade provided by these corals highlights concerns about future shifts in the structure of large reef fish communities as corals are lost. This is particularly concerning given the critical functional roles played by certain species of large reef fishes that utilize tabular structure for shelter and which occupy the lower ranks of the dominance hierarchy.'

biodiversity; climate change; dominance hierarchy; keystone species; UV irradiance

10.1007/s00338-015-1362-3

Funding provided by the Australian Research Council and a James Cook University GRS grant