Study site and sample collection
Sampling was conducted on Tetiaroa atoll (16°59’ S, 149°34’ E), French
Polynesia, during eleven nesting seasons from 2010/11 to 2020/21. Sample
collection was authorized and coordinated by the Direction of the
Environment of French Polynesia. Tetiaroa atoll has a total surface of 6
sq. km, about 585 hectares of sand, and is divided into 12 islets
(Figure 1). Between 2010/11 and 2017/18, 53 to 1316 nesting events per
season (July - April) were recorded by the local NGO Te mana o te
moana (Touron et al., 2018). Biopsies of approximately
0.5cm3 of skin and muscle tissues were collected from
the posterior fin of all the observed females and on all dead hatchlings
and embryos found. For a total of 6 nests, more than 10 hatchlings were
sampled. The laying date was either recorded when laying was directly
observed, or estimated when the nest was discovered. In this case, a
confidence interval of ± 3 days was applied to all of the estimations.
Since 2010/11, monitoring has gradually increased and by 2016/17, almost
all nests were sampled each season. However, nesting females were not
always observed. (Touron et al., 2018). Nest parameters such as clutch
size, number of hatchlings (estimated from empty eggshells), and number
of dead embryos were recorded for each nest. Samples were stored in 90%
ethanol and kept at 4°C or -20°C until processing.