The influence of structural complexity and reef habitat types on flight initiation distance and escape behaviors in labrid fishes

Structural complexity is a key parameter for fish on reef habitats. Several studies have investigated the influence of this variable on aspects of reef fish population and community dynamics. However, there is a lack of knowledge on the influence of structural complexity on antipredator behavior. Here we studied the effect of habitat type and structural complexity on flight initiation distance (FID) and the escape behaviors of four labrid fishes (Halichoeres brasiliensis, H. penrosei, H. poeyi and Sparisoma axillare) on two different reef habitats (coral and rocky reefs). Habitat type influenced the FID of three of the studied species (H. brasiliensis, H. penrosei and S. axillare), and structural complexity negatively influenced the FID of two species (H. brasiliensis and S. axillare). The frequency of escape behaviors varied between species. All of them showed high frequency of the 'run away' behavior and low frequency of the 'leave the habitat' behavior. On coral reefs, structural complexity influenced the 'fled to the holes' for S. axillare only. Reef ecosystems worldwide are being modified by anthropogenic activities. Our results suggest that if such activities reduce structural complexity, then 'seascapes of fear' for labrid fishes will become more widespread, which could lead to negative consequences in the reef ecosystems.