Meeting Abstract
The cues used by sea turtles to locate foraging areas in the open ocean are largely unknown but satellite tracks suggest that they often accomplish that feat. One possibility is that they locate those sites using chemical cues carried downwind in the air. Previous studies have shown that loggerheads (Caretta caretta) are capable of detecting airborne odors from synthetic food, as well as natural odors from mud and dimethyl sulfide (DMS), a substance that is found in high concentrations in highly productive oceanic areas. In this study, our goal was to determine if juvenile loggerhead and leatherback (Dermochelys coriacea) sea turtles, swimming in a water-filled tank, would orient into a laminar flow of air above the water that contained the odor of DMS or odors associated with particular prey items they are known to consume (shrimp, jellyfish, Sargassum, and squid). None of the turtles oriented into the air current. In other experiments, we examined how the turtles responded to air- and waterborne odors when a neutral visual stimulus (a small plastic ball) was suspended inside the water-filled tank. There was once again no response evoked by airborne DMS, but a food odor (squid) presented either in the water or in air induced both juvenile loggerheads and green turtles (Chelonia mydas) to orient toward the visual stimulus and attack it. We conclude that (i) air currents carrying either DMS or food do not induce turtles to orient upwind, (ii) turtles can detect and respond to food odors in air and underwater, and (iii) behavioral responses to food odors differ from those shown to DMS. None of our results provide support for the hypothesis that turtles locate productive areas in the ocean from long distances using odor cues.
