Refuge choice specificity increases with predation risk in a rocky reef fish

Abstract

Abstract Reef ecosystems are structurally complex and characterized by an array of abiotic (e.g., rocks and crevices) and biotic (sessile benthic organisms) physical features, many of which having the potential to act as refuge for prey organisms. Small cryptic reef fish species, including the redlip blenny, Ophioblennius trinitatis, rely on refuges to survive against predators, suggesting that adequate refuge choice is an important part of this species antipredator strategy. Here we investigated blennies selectivity in refuge choice along its ontogeny simulating predation risk in the field and laboratory. Our results revealed that when exposures to a predator model in the field, blennies chiefly fled to only two refuge types, namely crevices and sea urchins, and these choices reflected blennies ontogeny. Furthermore, blennies densities and flight-initiation distances were positively and negatively correlated with sea urchin densities, respectively, underscoring the refuge role played by this benthic organism. On high risk conditions, the fish translated into faster retreat to shelter and to higher refuge selectivity, when compared to low risk. The choices observed in situ were partly similar among initial and terminal phases. These findings suggest that small reef fishes may be selective in their refuge choice even using habitats with high structural complexity. This choice selectivity may be part of an antipredator strategy that considers the relative level of protection offered by the physical features of habitats, along with their conspicuity within rocky reef ecosystems.