Abstract
Abstract Egg translocation and incubation in man-made nests (MMN) are common conservation practices through marine turtle hatcheries worldwide. These measures have been associated with reduced hatching rates, altered hatchling sex ratio, fetal dysmorphic anatomical features and feeble hatchlings health. Previous studies have shown that MMN and natural nests (NN) provide different incubatory conditions. Therefore, incubatory challenges imposed by MMN conditions on fetal development could induce stress responses affecting hatchlings functional morphology later on life. There is no evidence of incubatory stress associated with conservation measures in turtle fetuses or hatchlings. Thus, in this paper we tested the hypothesis that MMN incubation exposes turtle fetuses to stressing conditions. Given that the hypothalamic-pituitary-interrenal axis begins functioning by day 11 of incubation in reptiles, our experiments explored the effects of incubatory conditions, rather than those associated with translocation, on fetal stress responses. We showed that Lepidochelys olivacea hatchlings incubated in MMN displayed reduced body weight, hypertrophic inter-renal glands, testicular hypotrophy and hypotrophic dorso-medial cortical pyramidal neurons, when compared with hatchlings emerging from NN. Furthermore, MMN hatchlings had higher serum levels of corticosterone at emergence, and displayed an attenuated acute stress response after traversing the beach. Therefore, the relocation of nests to protect them could negatively impact the health and survival of sea turtles. Thus, this action should only be undertaken when no alternative is available.
Highlights
Sea turtle populations have been declining through the last century (Sarti et al, 2007; Seminoff and Shanker, 2008)
Neurons in the dorso-medial cortex of man-made nests (MMN) hatchlings showed a reduced cell area [Nested ANOVA F(1, 13) = 11.998, ∗p = 0.004, Figures 3A,B] and decreased dendritic arbor complexity [Nested ANOVA Wald χ2(108) = 539.900, ∗p < 0.001, Figure 3C] when compared to those observed in natural nests (NN) hatchlings
It has been reported that MMN humidity, temperature (e.g., Reece et al, 2002; Arzola-González, 2007) possibly and microbiological (Bézy et al, 2014) conditions differ from those recorded for NN
Summary
Sea turtle populations have been declining through the last century (Sarti et al, 2007; Seminoff and Shanker, 2008). The creation of hatcheries where turtle eggs are translocated from natural nests (NN) and incubated in man-made nests (MMN) is one of the main strategies currently used. Hatcheries protect turtle eggs from poaching, predation, and beach erosion, factor all that could reduce marine turtles’ reproductive success (Seminoff et al, 2003; Abreu-Grobois and Plotkin, 2008). Egg translocation to and incubation in MMN is associated with reduced hatching and emergence success (Limpus et al, 1979; Parmenter, 1980; Eckert and Eckert, 1990; McElroy et al, 2015; Ahles and Milton, 2016), weak hatchling health (Maulany et al, 2012), misbalance sex ratio (Pintus et al, 2009), and increased frequency of fetal dysmorphic anatomical features (Sönmez et al, 2011). The precise mechanism underlying these negative outcomes is unclear, it is possible that mechanical, humidity, thermal and microbiological conditions (Chan et al, 1985; Booth and Astill, 2001; Arzola-González, 2007; Tuttle and Rostal, 2010; DeGregorio and Southwood, 2011; PatinoMartinez et al, 2012) in MMN could induce fetal incubatory stress responses
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