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Understanding an organism’s niche and ecological role in its ecosystem is critical for conservation, especially for species that use multiple habitats at different life stages. The hawksbill sea turtle ( Eretmochelys imbricata ) is one such migratory animal that plays an ecologically important role in imperiled coral reef habitats. Hawksbill resource use strategies (e.g., generalism vs. specialism) in these foraging grounds are poorly understood, yet stable isotope analysis of carbon ( δ 13 C) and nitrogen ( δ 15 N) can provide information on the trophic niche and foraging location of consumers. Additionally, when a single sample is taken from a tissue that accretes through time, such as keratin, analyses can reveal information on the long-term foraging patterns of individuals. Here, we evaluate resource use strategies for 98 females within a nesting aggregation of hawksbills on the island of Antigua (17.159, -61.756) in the Eastern Caribbean. Stable isotope analysis of scute tissue collected from 2017 to 2019 revealed population-level generalism and varying degrees of individual specialization. Additionally, reproductive age was significantly related to niche width, with younger turtles showing higher variability in their isotopic record. Older turtles displayed overall smaller ranges in isotope values, indicating a narrowing of resource use with increased reproductive age amongst breeding adult females. These findings provide evidence of high variability in hawksbill diet, illustrate differences in ecological niche use across different ages, and highlight the necessity of evaluating multiple life stages to inform the conservation of this critically endangered species.

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.

Maneja, R.H..; Miller, J.D., Flandez, A.V.B., Alcaria, J.F.A., Basali, A.U., Asiri, Y.Y., Panickan, P., Alnuwairah, M.A., Qurban, M.A.B., Lozano Cortes, D.F., and Qasem, A., 2024. Sea turtle stranding survey reveals mortality risks along the Saudi waters of the Western Arabian Gulf. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 901-905. Charlotte (North Carolina), ISSN 0749-0208. Stranding surveys for sea turtles were carried out along the eastern coast of Saudi Arabia in the Arabian Gulf in 2017 and 2018. Three transects representing the northern (Ras Mishab, 25-km), middle (Abu Ali Island, 37-km) and southern (Uqair, 47-km) coasts of the Eastern Province were monitored. The three sites were all exposed to the prevailing southward flowing coastal currents. Thus, stranding of sea turtles were highly likely along the sites. The survey was carried out using a quadbike All-Terrain-Vehicle following the water line along the beach. Stranded sea turtles were measured, marked, and buried along the beach berm. A total of 44 green and 4 hawksbill sea turtles were recorded during the surveys. Ras Mishab and Abu Ali each had 16 stranded green turtles while Uqair had 12 green turtles. Hawksbill turtles were found in Abu Ali Island and Uqair. Size frequency distribution of stranded green turtles showed that juvenile turtles were observed in all areas with smaller individuals recorded more in Uqair. The smallest stranded green turtle recorded was 26.3 cm curved carapace length in Uqair. Stranded adult green sea turtles were observed in all sites with more stranding recorded in Ras Mishab and Abu Ali Island. Population distribution of sea turtles is deduced based on the patterns of stranded turtle occurrence. Potential sources of mortality risks and conservation measures will be discussed.

Evaluating wildlife population trends is necessary for the development of effective management strategies, which are particularly relevant for highly threatened species. Hawksbill marine turtles ( Eretmochelys imbricata ) are considered endangered globally and are rare in Hawai‘i. Remnant hawksbill nesting beaches were identified in Hawai‘i in the late 1980s and the primary sites have been monitored since that time. In this study we summarize all available hawksbill nesting activity around the Hawaiian Islands between 1988 and 2018, highlighting relevant demographic and geographic data for the species. Because monitoring effort varied substantially across space and time, we implemented a predictive modeling approach that accounted for varying effort to explore potential trends in annual number of nesting females and nests over time. Field monitoring efforts documented an annual average of 14 ± 4.3 (range: 5–26) nesting females and 48 ± 19.0 (range: 12–93) nests, with a cumulative total of 178 individual nesting females and 1,280 nests recorded across all years. Nesting has been documented on four Hawaiian Islands, with the overwhelming majority of nesting females (78.4%) and nests (86.5%) recorded at four beaches along the southern coast of Hawai‘i Island. Recent monitoring (2018) at a beach on Moloka‘i Island revealed numbers similar to the most important beaches on Hawai‘i Island. Despite difficulty discerning obvious trends when looking solely at the raw tabulated numbers from field monitoring, our analysis suggests both the number of nesting females and nests have been positively trending since 2006, and this is supported by a higher percentage (57.1% of annual cohorts) of neophyte (vs. remigrant) nesters over the second half of the monitoring timeframe. The masking of obvious trends in the tabulated numbers is likely due to decreased overall monitoring effort as a result of reduced funding in recent years, coupled with a shift in focal monitoring effort from the historical primary nesting site of Kamehame, to the more recently established nesting site of Pōhue. Although the positive trend is encouraging, our findings highlight the precarious state of hawksbills in Hawai‘i and the need to enhance monitoring across all sites to support more robust population assessments and management decision making.

Sea turtles face significant threats from plastic ingestion, yet their behavioral responses to plastics remain poorly understood. We observed the responses of eight 4-year-old juvenile and twenty-seven 10-week-old post-hatchling captive-bred hawksbill turtles ( Eretmochelys imbricata ) to single-use plastic films with different colors and toughness, types commonly found in the digestive tracts of wild turtle carcasses. Each turtle’s biting or touching toward the introduced plastic item was recorded. Juveniles frequently bit or touched light-colored (transparent or white) packaging and plastic bags, black plastic bags, and yellow snack packaging, but ignored blue bottle labels. Their preference may reflect sensitivity to light colors (e.g., white), and to softer materials (i.e., plastic bags over packaging). These findings align with previous studies on sea turtle responses to undyed or dyed jellyfish ( Rhopilema esculentum ), and plastics in the digestive tracts of carcasses. However, post-hatchlings showed no significant differences in responses, likely due to limited prey recognition at an early life stage. This study represents the first assessment of sea turtle behavioral responses to single-use plastics as visual cues. While post-hatchlings may ingest plastic randomly, older turtles are vulnerable to light-colored, soft plastics, putting sea turtles at risk of plastic ingestion throughout all life stages. Action is needed for targeted management of high-risk debris.

While most studies assessing the ecological impacts of climate change have examined impacts from warming temperatures, less attention has been given to other parameters such as increased rainfall events. At a nesting rookery in the northern Great Barrier Reef, Australia, we used data loggers to examine the impact of heavy rainfall and shade on the nest temperatures for green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles clutches, which have temperature-dependent sex determination. In the middle of the nesting season (December–March), on 21 January 2019, 125 mm of rain fell over two days, causing the temperature to initially decrease by an average of ~ 3.6 °C in hawksbill turtle nests (n = 18) and ~ 3.5 °C in green turtle nests (n = 9). For shaded clutches during the 20-day cooling period after the rainfall event, we report average nest temperatures of ~ 27.9 °C and ~ 28.2 °C for hawksbill and green turtle clutches respectively, falling well into the male-producing range for sex determination. This was profoundly cooler than the average nest temperatures of clutches without shade and prior to the heavy rainfall, which was ~ 31.3 °C for both species. Extreme rainfall events are predicted to increase around Australia due to climate change but may help counteract impacts of atmospheric warming on sea turtle offspring sex-ratios. Our results also show the potential for artificially cooling nests by applying a combination of shade and irrigation, to counter the expected increases in the feminisation of sea turtle hatchling production worldwide.

Hatching season on the Caribbean island of Barbados is a busy time for Carla Daniel. Hatching season on the Caribbean island of Barbados is a busy time for Carla Daniel.

Little is known about the post-nesting migration and foraging areas of hawksbill turtles ( Eretmochelys imbricata ) nesting on St. Kitts and Nevis, an important nesting site for hawksbills in the eastern Caribbean. To elucidate internesting, migration and foraging patterns of hawksbills from Nevis, we satellite tagged 28 post-nesting turtles between 2006 and 2022. Internesting, migrating and foraging activity periods were determined using a switching state–space model to estimate the behavioral state of the turtle’s locations. Twenty-five turtles (83–2,171 tracking days) established a foraging area, migrating between 5.3 and 2,799.5 km from the nesting beach. Twenty-one turtles were tracked during internesting movements with internesting areas ranging between 1.9 and 28.2 km 2 . Nearly half of the internesting centroids were located closer to a different beach than the beach where the turtle was originally encountered nesting. Hawksbills crossed through 29 different Exclusive Economic Zones (EEZs), including zones with legal sea turtle fisheries or traditional subsistence use. Core foraging areas (KDE 50%) ranged between 3.8 and 69.0 km 2 . Nearly a third of foraging centroids were within a Marine Protected Area (MPA), while nearly a quarter were within a legal sea turtle fishery EEZ. Hawksbills nesting on Nevis disperse to local, regional, and Caribbean wide foraging grounds, emphasizing the necessity of cooperative efforts to protect turtles and their habitats to ensure support of the recovery of hawksbill turtles throughout the wider Caribbean.

Coastal areas provide critical nesting habitat for marine turtles. Understanding how artificial light might impact populations is key to guide management strategies. Here we assess the extent to which nesting populations of four marine turtle species—leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata) and two subpopulations of loggerhead (Caretta caretta) turtles—are exposed to light pollution across 604 km of the Brazilian coast. We used yearly night-time satellite images from two 5-year periods (1992–1996 and 2008–2012) from the US Air Force Defense Meteorological Satellite Programme (DMSP) to determine the proportion of nesting areas that are exposed to detectable levels of artificial light and identify how this has changed over time. Over the monitored time-frame, 63.7% of the nesting beaches experienced an increase in night light levels. Based on nest densities, we identified 54 reproductive hotspots: 62.9% were located in areas potentially exposed to light pollution. Light levels appeared to have a significant effect on nest densities of hawksbills and the northern loggerhead turtle stock, however high nest densities were also seen in lit areas. The status of all species/subpopulations has improved across the time period despite increased light levels. These findings suggest that (1) nest site selection is likely primarily determined by variables other than light and (2) conservation strategies in Brazil appear to have been successful in contributing to reducing impacts on nesting beaches. There is, however, the possibility that light also affects hatchlings in coastal waters, and impacts on population recruitment may take longer to fully manifest in nesting numbers. Recommendations are made to further this work to provide deeper insights into the impacts of anthropogenic light on marine turtles.