Nesting Ecology and Interactions Between Local and International Priorities for Hawksbill Sea Turtle (Eretmochelys Imbricata) Conservation on the Pacific Coast of Central America

Nesting Ecology and Interactions Between Local and International Priorities for Hawksbill Sea Turtle (Eretmochelys Imbricata) Conservation on the Pacific Coast of Central America
Author: Michael Joseph Liles
Publisher:
Total Pages:
Release: 2015
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ISBN:

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Despite human interaction with the biophysical environment since the beginning of human history, traditional research generally studied human and natural systems separately when addressing human-nature interactions. The purpose of my research is to better understand the nesting ecology and interactions between local and international priorities for hawksbill sea turtle (Eretmochelys imbricata) conservation in El Salvador and Nicaragua, where >90% of eastern Pacific hawksbill nesting occurs. In the first study, I explained the realities experienced by coastal residents who share habitat with hawksbills in El Salvador and then identified and clarified implications of discrepancies between these realities and international priorities for hawksbill conservation. The main findings were 1) primary importance of hawksbills is economic value attached to egg sales, but deeper cultural connections exist, 2) egg purchase by hatcheries benefits hawksbills and humans and 3) opportunities for local residents to participate in decision-making are limited and should be increased. In the second study, I characterized the microhabitat preferences and repeatability of nest-site choice by hawksbills, and then clarified the implications of doomed egg relocation programs on gene pools of hawksbills. I found 1) hawksbills preferred nest sites with abundant vegetation on dynamic beaches in mangrove estuaries, 2) female hawksbills exhibited local adaptations to differences in nesting habitat and 3) individual hawksbills consistently placed nests under high percentages of overstory vegetation, but were inconsistent in nest placement related to woody vegetation borders. In the third study, I generated and analyzed thermal profiles of hawksbill nest environments and estimated the sex ratios and physical condition of hatchling hawksbills under natural and artificial conditions. The primary findings were 1) minimal differences in temperature existed between sand depths, 2) adjustment of nest depth is unlikely to compensate for climate change, 3) in situ clutches incubated at higher temperatures and produced less fit offspring and 4) egg relocation can contribute to recovery efforts. The findings of these studies offer insight into interactions between hawksbill population dynamics and local community development on the Pacific coast of Central America, and demonstrate the value of implementing an evidence-based approach to guide public policy and conservation strategies. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155524

Assessing the Effect of Nesting Habitat on Hatch and Emergence Success of Hawksbill Sea Turtles Eretmochelys Imbricata on Buck Island St. Croix USVI

Assessing the Effect of Nesting Habitat on Hatch and Emergence Success of Hawksbill Sea Turtles Eretmochelys Imbricata on Buck Island St. Croix USVI
Author: Manouchehr D. Afshar
Publisher:
Total Pages:
Release: 2021
Genre: Hawksbill turtle
ISBN:

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Human-driven climate change is causing global temperatures to rise at an unprecedented rate, which poses a threat to several species around the globe. Hawksbill sea turtles (Eretmochelys imbricata) are susceptible to the effects of rising temperatures because of their terrestrial nesting behavior. High temperature can have a lethal effect on incubating their terrestrial nesting behavior. High temperature can have a lethal effect on incubating hatchlings and is known to influence the hatchling sex ratio. This study investigates the relationship between hawksbill nesting environment and hatch and emergence success on Buck Island Reef National Monument, St. Croix, USVI. The environmental variables distance to highwater mark (m), root density (g/cm3), canopy cover (% shade), organic carbon content of nest soil (%), the maximum mean daily incubation temperature (°C), mean three-day maximum incubation temperature (°C), and the number of days incubation temperature exceeded 34°C (NOD>34°C) were tested for effect on hatch and emergence success. Data was collected from 27 hawksbill nests during the 2018 field season. Historical nesting data was used to investigate possible shifting of habitat use over the 31 years of data collection on Buck Island Reef National monument, St. Croix, USVI. Multiple linear regression indicated a significant relationship between canopy cover and hatch success, and the number of days incubation temperature exceeded 34°C (NOD>34°C) and emergence success. Canopy cover was shown to have a positive linear relationship with hatch success, and NOD>34°C was shown to have a negative relationship with emergence success. In addition, the results from this study showed no significant shift in nest-site selection since 1988 on Buck Island.

Spatial Ecology of Hawksbill Turtles (Eretmochelys Imbricata) in the Eastern Pacific Ocean

Spatial Ecology of Hawksbill Turtles (Eretmochelys Imbricata) in the Eastern Pacific Ocean
Author:
Publisher:
Total Pages: 59
Release: 2011
Genre:
ISBN:

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Elucidating spatio-temporal movements of organisms is an integral component of wildlife management and life-history characterization. In the case of hawksbill turtles (Eretmochelys imbricata), adults have typically been described as coral reef dwellers, with females undertaking long post-nesting migrations. Until recently, hawksbills were thought to have been functionally extirpated in the eastern Pacific Ocean, a perspective changed by the identification of several substantial nesting rookeries. These discoveries provided new opportunities for research and conservation. Here we report on a region-wide satellite telemetry effort that has tracked thirteen adult female hawksbills in the eastern Pacific. In contrast to patterns of habitat use around coral reefs exhibited by their Caribbean conspecifics, the majority of hawksbills in the eastern Pacific occupied home ranges in mangrove estuaries. Post-nesting migrations for all turtles were relatively short (range = 18.1 km - 283.1 km) for the taxon, with several individuals remaining in local habitats after nesting. Also in contrast to previous research, dive computers indicated that adult hawksbills dove to and spent the majority of their time in the top 10 meters of the water column. Our findings suggest that common perceptions of hawksbill habitat use, dive behavior and migrations, largely Caribbean-based, have overlooked some key characteristics of this species displayed by other populations. Moreover, the consistent use of mangrove habitats, use of superficial waters and non-migratory behaviors represent a new life-history paradigm for the species and may explain why hawksbills went virtually undetected in the eastern Pacific for decades. From a conservation standpoint, the spatially restricted, shallow and neritic life cycles of hawksbills in the eastern Pacific present both threats to and conservation opportunities for the species. Although a large proportion (>60%) of turtle location points fell within protected areas, many of these sites lack enforcement and monitoring. Our results underscore the importance of strengthening protected area management, mangrove conservation and hawksbill research and conservation in the eastern Pacific. Furthermore, our findings highlight the variability in life-history strategies that sea turtles and other longlived marine wildlife may exhibit among ocean regions.