Abstract
Relatively few details of hawksbill turtle (Eretmochelys imbricata) nesting ecology exist within the Arabian Gulf. Moreover, little is known about how their nesting dynamics compare to nesting populations throughout the rest of the world. Due to the extreme environmental setting, nesting ecology of hawksbills in the Arabian Gulf is of significant interest to researchers and conservationists. The current research reports on a long-term tagging and monitoring program undertaken at Fuwairit beach, Qatar. To investigate nesting behavior, site surveys and tagging were employed from 2010 to 2016. Presence of nests and clutch sizes were confirmed by excavation. Over the entire study period, nesting hawksbills had a mean curved carapace length of 70.8 cm (SD±2.8). A total 187 nests were confirmed, which contained a mean 78.9 eggs per clutch (SD±17.1), over an annual nesting season that lasted an average of 52.2 days (SD±6.3) from the start of April to the start of June. Meta-analysis with other global regions showed these characteristics to be significantly reduced when compared to nesting hawksbills from other populations. Meteorological data analysis showed air temperatures in the Arabian Gulf to increase on average 13.2°C (SD±0.26) from start to the end of nesting annually, which is significantly greater than other global nesting regions. Their smaller body size and reduced fecundity coupled with the extreme change in ambient air temperatures support the hypothesis that hawksbills in the region are more at risk than the already critically endangered hawksbill populations elsewhere in the world.
Highlights
Hawksbill sea turtles (E. imbricata), listed as critically endangered by the IUCN (International Union for the Conservation of Nature), have a well-documented circum-global distribution [1,2,3,4,5,6,7]
Curved Carapace Length and Carapace Width (CCW) showed no significant variation with year (CCL Analysis of Variance (ANOVA): F 1,89 = 1.819, p = 0.18 and ANOVA: F 1,89 = 0.027,p = 0.87 respectively)
A mean observed Internesting Interval (OII) of 14.8 days (SD± 1.9) was observed, which coincided with a mean Observed Clutch Frequency (OCF) and Estimated Clutch Frequency (ECF) of 1.4 (SD± 0.7) and 1.5 (SD± 0.9), respectively (S1 Fig)
Summary
Hawksbill sea turtles (E. imbricata), listed as critically endangered by the IUCN (International Union for the Conservation of Nature), have a well-documented circum-global distribution [1,2,3,4,5,6,7]. Nesting aggregations have been recorded throughout tropical and, to a lesser extent, subtropical waters of the Atlantic, Indian, and Pacific Oceans [1,3,8,9,10]. Research throughout these locations has shown variations in nesting ecology which may be driven by regional environmental differences [3,4,11,12]. Recent evidence has suggested that hawksbills in the region are smaller and lay smaller clutches [13,14], to date, limited work has focused on comparing nesting dynamics of these populations to their tropical counterparts. No work has used statistical analysis to confirm whether apparent differences reproductive ecology are significant
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