Quantification of The Effects of Coral Reef Degradation On Butterflyfish Populations in The Southern Great Barrier Reef

Abstract

Bryanna M Andrews and Alexa KS Kownacki

Because of their wide abundance on coral reefs, butterflyfishes’ presence or absence can function as an indicator for overall reef health. A survey of both healthy and degraded coral reef flats off Heron Island in Queensland, Australia was conducted to determine the effects of decreasing coral cover on corallivorous fishes. During a four-day period at the end of October, 2013, four species of butterflyfish – two obligate and two facultative corallivorous butterflyfish species – were tallied along two transects in the reef flats. From a total of 291 individuals, there was a significant difference in habitat composition choice between healthy and degraded habitats seen by a p= 2.234e-10. Additionally, means extracted from log-transformed data suggest that the twelve percent decrease in live coral between transects of the healthy habitat caused a disproportionate decrease in fish abundance. This suggests that a minor loss of coral cover can result in a dramatic loss of fish abundance and diversity and may point towards a threshold where living coral can no longer sustain original population abundances of coral reef communities.

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