Intraspecific variation in sand-diving and predator avoidance behavior of green razorfish, Xyrichtys splendens (Pisces, Labridae): effect on courtship and mating success

Abstract

Green razorfish are Caribbean wrasses that live in harems on shallow sand or seagrass beds, which offer little cover for predator avoidance (PA). Field observations showed that non-conspecific fishes that intruded were either attacked, ignored, or actively avoided. Food competitors and small piscivores were attacked by male razorfish. Razorfish PA behaviors varied among three habitats with different substratum compositions, suggesting that these fish possess phenotypic plasticity for PA behavior. In a rocky-rubble habitat, razorfish dove into the coarse sand for PA, but most sand dives observed there were to soften a small site for future PA. In a sandbed habitat, they hid among coral branches and dove into the sand when attacked; few maintenance dives were observed as soft sand was widespread. In a seagrass habitat, they hid among blades of grass for PA, and dove into the sand less frequently than at the other sites. Some female razorfish that were transferred among habitats adopted PA behaviors similar to those of females in the new site, while others did not, suggesting that behavioral plasticity is not universal in this species. Razorfish spawned lower in the water column in the presence of natural predators and a predator model, than when these were absent. When the predator model was introduced into a male’s territory during spawning periods, there was a reduction in his courtship rate, but not in the number of spawns he achieved. Predation pressure may reduce males’ long-term fitness by causing decreased courtship rates which can facilitate sex change in harem females.