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Brown University

Publication Date

Fall 2011

Program Name

Australia: Rainforest, Reef, and Cultural Ecology

Abstract

Coral predators have always been a natural occurrence on coral reefs, but recent studies have begun to focus on the feeding preferences of these predators in relation to bleached and damaged corals. The recent mass bleaching events, mainly resulting from factors of climate change, have motivated researchers to study the effects of predation on the affected corals to determine the extent of harm these large-scale disturbances may be causing to reefs. This study examined how coral stressing affects the feeding preferences of Acanthaster planci, a coral-feeding starfish that has been known to cause widespread damage to coral reefs, especially during periods of outbreaks. By determining whether A. planci prefers to prey on stressed or healthy coral colonies in a controlled aquarium setting, we can apply these findings to situations in the wild, relating them to the vulnerability of coral reefs after stressing events. This study was set up as a simple, two-choice, observational experiment, where an A. planci specimen was placed in a tank with a healthy colony of Pocillopora damicornis and a similar colony that had been submerged in freshwater several times. Out of 32 nights of trials, 1 trial resulted in A. planci choosing the healthy coral, 14 trials resulted in the starfish choosing the stressed coral, and no choice was made in 17 trials. Significant differences were found between the average proportion of trials resulting in the choice of healthy coral and those resulting in the choice of stressed coral (T-test for Independent Samples: p = 0.016; Chi-square test:p = 0.0011). This shows that A. planci selectively preys on stressed coral over healthy coral, opening up numerous questions as to what kind of motivations may be driving this preference, and how these findings will affect the persistence of coral reefs during increasingly frequent bleaching events.

Disciplines

Environmental Indicators and Impact Assessment | Terrestrial and Aquatic Ecology

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