Behavior of the Princess parrotfish (Scarus taeniopterus): a comparison between daylight and sunset

Most animals are active either during the day or night, and at twilight, nocturnal and diurnal animals alike engage in behaviors to avoid predators, seek shelter, defend territory, or feed. Herbivorous fishes on coral reefs, such as parrotfishes, forage throughout daylight periods due to reliance on light and low nutrient content of algae. At sunset, parrotfishes seek cover to avoid predation during the night, resulting in less feeding and more aggressive behavior. This study compared how initial phase (IP) and terminal phase (TP) Princess parrotfish (Scarus taeniopterus) allocate time between daylight and sunset periods, specifically regarding feeding and aggressive behavior, on the fringing reefs of Bonaire, Dutch Caribbean. Using SCUBA, individual S. taeniopterus between 11 and 14 m depth were followed for 5 min after a 1 min acclimatization period, and time spent on each behavior was recorded. A two-way analysis of variance (ANOVA) was used to compare the amount of time S. taeniopterus spent feeding and in aggressive interactions between day and sunset periods, with phase and time of day as factors. Fish of both phases had a higher mean percent time feeding and a lower mean percent time being aggressive in the morning than at sunset. There was a significant difference in mean percent time feeding between phases, and TP fish had a significantly higher mean percent time being aggressive than IP fish. The changes in behavior found in this study increase the success of S. taeniopterus finding and keeping quality nighttime resting locations.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 45-51 from CIEE Bonaire.