Marine Ecology Progress Series 511:193
This authors' personal copy may not be publicly or systematically copied or distributed, or posted on the Open Web, except with written permission of the copyright holder(s). It may be distributed to interested individuals on request. Vol. 511: 193–207, 2014 MARINE ECOLOGY PROGRESS SERIES Published September 24 doi: 10.3354/meps10921 Mar Ecol Prog Ser Predation risk, competition, and territorial damselfishes as drivers of herbivore foraging on Caribbean coral reefs Laura B. Catano*, Andrew A. Shantz, Deron E. Burkepile Marine Science Program, Department of Biological Sciences, Florida International University, 3000 NE 151st Street, North Miami, FL 33181, USA ABSTRACT: Food availability, competition, habitat complexity, and territorial damselfish shape foraging decisions of herbivorous coral reef fishes. However, relatively little is known about how predators affect herbivore diet selection. We examined diets of 2 common reef herbivores, Sparisoma aurofrenatum and Acanthurus coeruleus, in the Florida Keys, across sites of varying predator biomass. We used stable isotope analysis to understand the importance of predation risk relative to other known drivers of herbivore foraging decisions. For S. aurofrenatum, we found that greater predator biomass was associated with an increase in the diversity of resources con- sumed within populations. In contrast, increasing densities of damselfishes, which aggressively defend resource-rich algal gardens, were associated with lower diet diversity. However, within A. coeruleus populations, diet diversity increased with damselfish abundance, but was unrelated to predator biomass. Stomach content analyses and direct observation of diet selection in the field corroborated the stable isotope analysis. Importantly, both predator and damselfish abundance impacted diet diversity in different ways for these 2 fishes, which may be linked to differences in sociality and group foraging.
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