Predators can exert strong direct and indirect effects on ecological communities by intimidating their prey. The nature of predation risk effects is often context dependent, but in some ecosystems these contingencies are often overlooked. Risk effects are often not uniform across landscapes or among species. Indeed, they can vary widely across gradients of habitat complexity and with different prey escape tactics. These context-dependencies may be especially important for ecosystems such as coral reefs that vary widely in habitat complexity and have species-rich predator and prey communities. With field experiments using predator decoys of the black grouper (Mycteroperca bonaci), we investigated how reef complexity interacts with predation risk to affect the foraging behavior and herbivory rates of large herbivorous fishes (e.g., parrotfishes and surgeonfishes) across four coral reefs in the Florida Keys (USA). In both high and low complexity areas of the reef we measured how herbivory changed with increasing distance from the predator decoy to examine how herbivorous fishes reconcile the conflicting demands of avoiding predation vs. foraging within a reefscape context. We show that with increasing risk, herbivorous fishes consumed dramatically less food (ca. 90 %) but fed at a faster rate when they did feed (ca. 26 %). Furthermore, we show that fishes foraging closest to the predator decoy were 40 % smaller than those that foraged at further distances. Thus, smaller individuals showed muted response to predation risk compared to their larger counterparts, potentially due to their decreased risk to predation or lower reproductive value (i.e., the asset protection principle). Habitat heterogeneity mediated risk effects differently for different species of herbivores, with predation risk more strongly suppressing herbivore feeding in more complex areas and for individuals at higher risk of predation. Predators appear to create a reefscape of fear that changes the size structure of herbivores towards smaller individuals, increases individual feeding rates, but suppresses overall amounts of primary producers consumed, potentially altering patterns of herbivory, an ecosystem process critical for healthy coral reefs.

JAE_Grouper_Decoy_DataThis dataset includes the five foraging metrics quantified during predator and control trials including: (a) percentage of seagrass consumed/hour, (b) bites on seagrass/hour, (c) bites on benthos/hour, (d) individual feeding rates (bites/minute) and (e) forager size (cm). The data is aggregated by plot and by distance from the predator decoy. Additionally, we include the number of natural predators observed from video footage aggregated at the site level and at the distance level. Metadata is included in the file describing each column.JAE_Video_DataThis dataset includes observations from video footage during both predator and control treatments. Each line in the datasheet is a single foraging episode by a herbivore on either the seagrass assay or on the benthos surrounding the assay. The foray number and bites taken are entered in separate columns and the individual foraging rate (bites/second) was calculated and included in another column. Predators and mesopredators that were observed in the field of view are recorded on separate rows. The number of territorial damselfish observed in the area surrounding the seagrass assay at each distance from the predator decoy is shown in a separate column. Metadata describing the data is included in the file.