Influence of Shading on the Behavioral Ecology of a Caribbean Alcyonacean Octocoral, Briareum asbestinum, in the Florida Keys, United States

Using a restricted set of behavioral responses, corals must obtain sufficient light to maximize photosynthesis while simultaneously avoiding predation and molecular damage from UV radiation. This study investigates the polyp behavioral response of the Caribbean octocoral Briareum asbestinum to shading, and how this response influences reactions to a simulated predator cue. In experiment I, we measured changes in polyp extension before and after a shade structure was placed over colonies on a shallow patch reef in the Florida Keys. In experiment II, changes in polyp extension were measured following a simulated predator cue for both shaded and un-shaded colonies. Experiment I demonstrates that B. asbestinum possesses a mechanism for detecting changes in light intensity and responds by manipulating the extension of its polyps. Following polyp retraction due to a predator cue in experiment II, the temporal pattern of polyp re-extension differed between shaded and non-shaded colonies, and at the end of the observation period, shaded colonies had a greater proportion of extended polyps than non-shaded colonies, consistent with the results of experiment I. This research provides novel and valuable insights into the behavior of a common and important Caribbean octocoral and will serve as a foundation for future research pertaining to the physiological processes involved.