Meeting Abstract

2.4  Saturday, Jan. 4 08:45  Risk vs. reward effects on reef fish herbivory GIL, MA; University of Florida m.gil@ufl.edu

Perceived risk of predation drives species distributions and key interactions across terrestrial and aquatic ecosystems. Optimal foraging theory posits that decisions to forage are determined by an individual’s perception of the trade-off between risk and reward. Many reef fishes are known to prefer close proximity to structural habitats (e.g., corals) that provide a refuge from predators, but the effects isolation from reef habitat on key ecological processes are poorly understood. In this study, I examined the relationship between distance from reef habitat and herbivory, and whether this relationship depends on the quality of the ‘reward’ (food) being offered. I measured algae loss over time from turf and macroalgae “platters” on cinderblocks at 5 levels of isolation (within reef, as well as 5, 10, 20, and 30 m from the reef edge) and 2 levels of quality (1 thallus versus 4 thalli per algal species per plot) across 6 study sites. My results indicated that distance had a significant negative effect on the proportion of algae consumed but no significant interaction was detected between distance and quality. These results suggest that habitat isolation could be an important factor weakening top-down control of algae on reefs, especially those receiving nutrient enrichment. Using video analyses of the experimental trials, I am now exploring consumer behaviors that could be driving the herbivory patterns observed.