Bleaching corals of two species appear to feed from neighboring algal turfs
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KeywordsMicroalgae Coral Reef Macroalgae Dinoflagellate Coral Bleaching
Turf algae are known to exude glucose and other photosynthetic products from their tissues (Haas et al. 2010). The bleaching corals may have used their extended mesenteries to feed on this photosynthate, on the diatoms, microalgae, and heterotrophic bacteria shown to be associated with the macroalgae at this same study site (Barott et al. 2011), and/or on the microfauna sheltered within the turfs. Colpophyllia natans is known to fight neighboring corals using its relatively long mesenterial filaments; however, neither C. natans nor M. faveolata is known to “fight” algal turfs. Furthermore, this behavior was observed only during an extended coral bleaching event and never in 30 preceding hours of nighttime observation or 100+ total hours of observation at this site (Water Factory, Curaçao, 12°10′91″N, 68°95′49″W). Thus, the behavior described here is most likely a feeding strategy used by corals undergoing an extended period of bleaching. Because most research on coral bleaching is conducted during the day, the generality of this behavior is not known. More broadly, this observation highlights the fact that simultaneous changes to reef health and community structure (such as more frequent coral bleaching events and long-term increases in turf algal cover) may occur for different reasons and at different rates but may nevertheless act together to reveal previously unknown acclimatization behaviors in coral reef organisms.