Meeting Abstract
The outcome of interactions between predators and prey can depend critically on the environmental context in which they take place. Certain aspects of habitats may give predators an advantage by inhibiting the ability of prey to detect or evade predation attempts. In fishes, one of these habitat features could be water flow. Our previous lab studies of juvenile Hawaiian stream gobies found that prey fish respond less frequently to simulated attacks occurring in the same direction as the dominant flow of water. We sought to test whether predators take advantage of this ‘blind spot’ during actual attacks in the field. We used an array of GoPro cameras to film instream attacks on juvenile gobies by Eleotris sandwichensis, ambush hunters that sit on the bottom of the steam and attack juvenile gobies as they migrate upstream from the ocean. From these videos, we calculated three measurements. First, we measured the angle between the attacking predator relative to the prey’s upstream orientation, the pre-strike angle. Second, we measured the predator orientation relative to the stream bottom, the perch orientation. Third, we measured the success rates of predator’s strikes. Our results indicate that E. sandwichensis, are successful in approximately one-third of their attacks. There was no preferential association of attacks with a particular direction, suggesting that predators are not targeting their attacks with the ‘blind spot’ of their prey. However, when predators do strike from the same direction as stream flow, they are more likely to successfully capture prey. Our study of these interspecific interactions in the natural environment where they occur provided an outstanding opportunity to test lab-based hypotheses under ecologically relevant conditions.
