19 July 2019
Arabian hawksbill turtles vulnerable to rising temperatures
Published online 22 September 2018
Their fertility and offspring are at stake.
Come April, Fuwairit beach in Qatar becomes home to its seasonal guests, the Arabian Gulf hawksbill turtles. Lingering there till early June, the female hawksbills lay and incubate eggs, giving birth to baby turtles.
On their way to sea, most of the newborns fall prey to poachers and predators. Now, they also face increasing sea surface temperatures and hotter sands.
A recent study has found that rising temperatures are affecting the hawksbills’ hatching potential and the birth of their hatchlings, ultimately reducing their fertility.
Low fertility makes the Arabian hawksbills more vulnerable than their already endangered counterparts elsewhere in the world, says lead author Mark Chatting from Qatar University.
To date, little is known how the hawksbills thrive in extreme sub-tropical environments where summer sea surface temperatures rise to 35°C, accelerating evaporation and making the seawater highly saline.
Chatting and colleagues in Qatar and the USA tagged individual female hawksbills that came to lay eggs on Fuwairit beach. They monitored the turtles throughout the nesting season, which usually lasts from the start of April to early June.
After monitoring the tagged turtles for a period of seven years, they found that the average length of the females was 74 cm, which is smaller than female sea turtles living in other parts of the world. Air temperatures showed a drastic rise from the start to end of each nesting season, which is why the nesting season in the region is shorter than that in other parts of the world.
“A short nesting season coupled with a harsh marine environment affects the size of the female hawksbills, making them smaller than other female sea turtles,” says Chatting. They also lay fewer eggs per clutch than turtles elsewhere in the world, he adds.
Rising temperatures could also affect their adult sex ratio. Since heat determines the sex of developing embryos, higher temperatures in nests are associated with female-skewed hatchling sex ratios. This could significantly change adult sex ratios in the region resulting in a population with fewer males, explains Chatting.
Jeanette Wyneken, an expert on sea turtles from Florida Atlantic University in the USA appreciates the value of this preliminary research on the hawksbills. However, “the study lacks data on hatchling emergence success and the number of nests per individual; two facts important for assessing the fecundity and survival strategy of the hawksbills,” she points out.
Chatting, M. et al. Nesting ecology of hawksbill turtles, Eretmochelys imbricata, in an extreme environmental setting. PLOS ONE https://doi.org/10.1371/journal.pone.0203257 (2018).