Seleção de habitat baseada em pistas quimiossensoriais em filhotes de Tartarugas Cabeçudas (Caretta caretta Linnaeus, 1758)

Abstract

After hatching on land, hatchling sea turtles need to reach the marine realm. However, whether hatchlings orient themselves to reach a preferred habitat at sea, which may vary among species from coastal (inshore) to oceanic (offshore), and whether this process is mediated by chemoreception, is almost entirely unknown. Given that adult turtles may rely on chemoreception for guidance at sea, it is possible that hatchlings’ first migration is likewise based on this sensory mechanism. However, chemoreception is often impaired by chemical pollution, which may lead to exposure to contaminants. In one endangered sea turtles species, Caretta caretta, based on chemoreception, we determined whether this species preferred chemical cues from two distinct habitats (coastal or oceanic), and whether coastal chemical pollution is avoided. In a flume, we concomitantly presented distinct seawater flows (coastal vs. oceanic [Exp. 1] and coastal vs. polluted-coastal [Exp. 2]). Hatchlings had free access to these flows for a period of 10 min. In the first experiment, hatchlings spent significantly more time in oceanic seawater flow, with nearly 70% of the time. In the second experiment, when hatchlings had to choose between coastal and polluted-coastal water (collected from a urban sewage outlet), these did not distinguish between flows, suggesting that this polluted water was not recognized and avoided. Thus, it appears that hatchlings are abled to recognize between distinct habitats based on chemical cues, but not to evolutively more recent cues associated with anthropogenic chemical pollution, suggesting a propensity to contamination that may put turtle populations at risk.