Effect of Sand Types on the Early Swimming Performance of Green Turtle Hatchlings

Abstract The selection of the nest site is a critical factor whereby female turtles may choose to nest at the site that minimizes energy expenditure of hatchlings and time spent to construct the nest. Nest substrate such as grain size is hypothesized to influence hatchling fitness by affecting the amount of energy reserves used by the hatchlings during emergence. Throughout Malaysia more than half a million green turtle hatchlings are released from hatcheries annually, however the question of whether this practice is producing high-quality hatchlings remains unanswered. It is crucial to hatchery management to identify which types of sand are most suitable for egg incubation and beneficial for hatchlings during nest emergence. We measured the influence of sand types on hatchlings fitness in terms of self-righting ability and swimming performance which emerged from the coarse and fine grained sand. Ten nests which had reach 45 days of incubation duration were selected as the developing embryos would be robust enough to be transported from the nesting to the laboratory for further incubation. Eggs from each clutch were split and allowed to continuing incubating in two different experimental conditions, fine and coarse grain. After hatched, the morphological characteristics and self-righting ability of hatchlings were measured then placed inside the glass aquarium to test the swimming performance for 18 hours. Results revealed that sand types only influenced the straight carapace width (SCW) of hatchlings but had no effect on their swimming. Cooler nest temperatures and longer incubation periods in nests constructed in fine sand caused the hatchlings to have larger straight carapace width than hatchlings from coarse sand. We suggest that the relocation of eggs in the late incubation period within Chagar Hutang beach is fine. Hence, we concluded that green turtle hatchlings emerging from nests in either fine or coarse grain sands of Chagar Hutang beach did not have a significant impact on their swimming performance.