Predator Avoidance in Seagrass Meadows: Prey Behavior, Microhabitat Selection, and Cryptic Coloration

Abstract

Behavioral responses to predators may influence distribution and abundance patterns of prey. Earlier predator—preference experiments and analyses of natural diets revealed that the caridean shrimp Tozeuma carolinense is underrepresented in the diet of pinfish, Lagodon rhomboides, the dominant predatory fish in marine seagrass meadows in the southeastern USA. I examined the influence of prey behavioral responses, microhabitat shifts, and cryptic coloration on prey accessibility to Lagodon with a combination of field observations and laboratory experiments. Tozeuma's behavior and microhabitat choice were extremely similar in the field and the laboratory and were tightly coupled to the seagrasses Tozeuma inhabits. In the presence of predatory fishes, Tozeuma increased the time spent in some otherwise rare behaviors. In particular, laboratory experiments revealed that the behavioral response of moving around the grass blade, to which a shrimp was clinging, resulted in a significant increase in shrimp survival, and thus is strongly adaptive. In addition, Tozeuma shifted microhabitats in response to predators; individuals that did not respond were often consumed. For the shrimp, predator—avoidance behaviors were far more important than cryptic coloration in eluding predatory fish. The presence of a physical structure alone did not necessarily provide protection for shrimp from these visual predators; the combination of active predator—avoidance behaviors and the presence of a structurally complex, opaque substrates resulted in a visual barrier between predator and prey. Such prey behavior—microhabitat links can be more important than physical interference of the habitat as factors affecting foraging success of visual predators.