Jeanne A. Mortimer

Global Conservation Priorities for Marine Turtles

Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a “conservation priorities portfolio” system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the worlds 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.

Regional Management Units for Marine Turtles: A Novel Framework for Prioritizing Conservation and Research across Multiple Scales

Background Resolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques — including site-based monitoring, genetic analyses, mark-recapture studies and telemetry — can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges. Methodology/Principal Findings To address these issues for marine turtles, we collated all available studies on marine turtle biogeography, including nesting sites, population abundances and trends, population genetics, and satellite telemetry. We georeferenced this information to generate separate layers for nesting sites, genetic stocks, and core distributions of population segments of all marine turtle species. We then spatially integrated this information from fine- to coarse-spatial scales to develop nested envelope models, or Regional Management Units (RMUs), for marine turtles globally. Conclusions/Significance The RMU framework is a solution to the challenge of how to organize marine turtles into units of protection above the level of nesting populations, but below the level of species, within regional entities that might be on independent evolutionary trajectories. Among many potential applications, RMUs provide a framework for identifying data gaps, assessing high diversity areas for multiple species and genetic stocks, and evaluating conservation status of marine turtles. Furthermore, RMUs allow for identification of geographic barriers to gene flow, and can provide valuable guidance to marine spatial planning initiatives that integrate spatial distributions of protected species and human activities. In addition, the RMU framework — including maps and supporting metadata — will be an iterative, user-driven tool made publicly available in an online application for comments, improvements, download and analysis.

The Influence of Beach Sand Characteristics on the Nesting Behavior and Clutch Survival of Green Turtles (Chelonia mydas)

the thermal sensitivity of sprint speed in Anolis lizards. Evolution 40:594-604. WERNER, E. E. 1986. Amphibian metamorphosis: growth rate, predation risk, and the optimal size at transformation. Amer. Nat. 128:319-341. WHITEHEAD, P. J., J. T. PUCKRIDGE, C. M. LEIGH AND R. S. SEYMOUR. 1989. Effect of temperature on jump performance of the frog Limnodynastes tasmaniensis. Physiol. Zool. 62(4):937-949. WILBUR, H. M. 1980. Complex life cycles. Ann. Rev. Ecol. Syst. 11:67-93. ZUG, G. R. 1972. Anuran locomotion: structure and function. I. Preliminary observations on the relation between jumping and ostometrics of the appendicula and postaxial skeleton. Copeia 1972: 613-624. . 1978. Anuran locomotion-structure and function 2: jumping performance of semiaquatic, terrestrial, and arboreal frogs. Smithsonian Contrib. Zool., no. 276. -. 1985. Anuran locomotion: fatigue and jumping performance. Herpetologica 41:188-194.

Reproduction and migrations of the Ascension Island green turtle (Chelonia mydas)

TOME, M. A., AND F. H. POUGH. 1982. Responses of amphibians to acid precipitation, p. 245-254. In: Acid rain fisheries. R. E. Johnson (ed.). Proceedings of an International Symposium on Acid Precipitation and Fisheries Impacts in Northeastern North America, 2-5 August 1981, Ithaca, New York. American Fisheries Society, Bethesda, Maryland. (BAP) DEPARTMENT OF BIOLOGY, BAYLOR UNIVERSITY, WACO, TEXAS 76798 AND (JMH) DEPARTMENT OF ZOOLOGY, CONNECTICUT COLLEGE, NEW LONDON, CONNECTICUT 06320. Accepted 17 April 1986.

Reproductive biology of the Hawksbill Eretmochelys imbricata at Tortuguero, Costa Rica, with notes on the ecology of the species in the caribbean

Abstract From 1955 through 1983, 246 hawksbills Eretmochelys imbricata have been tagged as they came ashore to nest at Tortuguero, Costa Rica, a beach they share with a large colony of green turtles Chelonia mydas . Nesting hawksbills average 82 cm in straight carapace length and grow at a mean rate of 0·3 cm year −1 . Mean clutch size is 158 eggs; clutch size is poorly correlated with female body size. Average time from egg deposition to hatching emergence is 58·5 days. Mean emergence success ff hatchling is 58·3% in all clutches and 91·6% in clutches that produced hatchlings. The internesting interval averaged between 16 and 17 days. Site-fixity of females both within and between seasons was examined; a greater degree of site-fixity was exhibited between seasons than within. The distribution of hawksbill nesting activity at Tortuguero is spatially similar to, but temporally different from, that of the green turtle. There is increasing evidence from tag returns that the Tortuguero hawksbill may also share the feeding grounds of the Tortuguero green turtle in the Miskito Cays, Nicaragua. Notes on the movements and feeding habits of juveniles on their feeding grounds are included. Following a decline from 1956, there has been no consistent trend in the number of hawksbills nesting at Tortuguero since 1972. However, the mean carapace length of hawksbills has shown a steady decline, suggesting that the population is not demographically stable. The stability of an entire population cannot be determined from monitoring the number of nesting turtles each year.

Reproductive homing and internesting behavior of the green turtle (Chelonia mydas) at Ascension Island, South Atlantic Ocean

Female green turtles (Chelonia mydas) were tagged while nesting on the 32 cove-head beaches distributed in four clusters along the leeward shoreline of Ascension Island. The turtles showed high nesting site fidelity, returning to the same beach cluster during at least 70% of consecutive observed renesting emergences. Stronger site fidelity to beach clusters and also to points within the boundaries of a beach was more evident in emergences separated by less than 7 d (assumed to be repeated attempts to lay one clutch of eggs) than in nestings separated by longer time intervals, involving separate egg clutches. These differences correlate with predictable patterns of behavior observed in females, the movements of which were visually tracked during their internesting intervals. After successful oviposition, most of the tracked females traveled to a shallow area off the northwest coast of the island. Those that did not lay eggs remained in the vicinity of the beach just abandoned, traveling back and forth in nearshore waters until daylight when they moved into deeper water. The rates, patterns and periodicities of travel by Ascension turtles in their internesting habitat after successful and aborted nestings are compared with those of internesting female turtles at other breeding grounds; possible explanations for observed differences are discussed.

Whose turtles are they, anyway?

The hawksbill turtle (Eretmochelys imbricata), listed since 1996 by the IUCN as Critically Endangered and by the Convention on International Trade in Endangered Species (CITES) as an Appendix I species, has been the subject of attention and controversy during the past 10 years due to the efforts of some nations to re‐open banned international trade. The most recent debate has centred on whether it is appropriate for Cuba to harvest hawksbills from shared foraging aggregations within her national waters. In this issue of Molecular Ecology, Bowen et al. have used molecular genetic data to show that such harvests are likely to have deleterious effects on the health of hawksbill populations throughout the Caribbean.

Nesting phenology of marine turtles: insights from a regional comparative analysis on green turtle (Chelonia mydas).

Changes in phenology, the timing of seasonal activities, are among the most frequently observed responses to environmental disturbances and in marine species are known to occur in response to climate changes that directly affects ocean temperature, biogeochemical composition and sea level. We examined nesting seasonality data from long-term studies at 8 green turtle (Chelonia mydas) rookeries that include 21 specific nesting sites in the South-West Indian Ocean (SWIO). We demonstrated that temperature drives patterns of nesting seasonality at the regional scale. We found a significant correlation between mean annual Sea Surface Temperature (SST) and dates of peak nesting with rookeries exposed to higher SST having a delayed nesting peak. This supports the hypothesis that temperature is the main factor determining peak nesting dates. We also demonstrated a spatial synchrony in nesting activity amongst multiple rookeries in the northern part of the SWIO (Aldabra, Glorieuses, Mohéli, Mayotte) but not with the eastern and southern rookeries (Europa, Tromelin), differences which could be attributed to females with sharply different adult foraging conditions. However, we did not detect a temporal trend in the nesting peak date over the study period or an inter-annual relation between nesting peak date and SST. The findings of our study provide a better understanding of the processes that drive marine species phenology. The findings will also help to predict their ability to cope with climate change and other environmental perturbations. Despite demonstrating this spatial shift in nesting phenology, no trend in the alteration of nesting dates over more than 20 years was found.

Recovery of green turtles on Aldabra

The numbers of green turtles that nest on Aldabras beaches have increased significantly in the past 20 years. The author, who studied the turtles between 1981 and 1984, suggests explanations for the recovery. It is likely that the Aldabra population is still well below that which thrived there before exploitation began, and with sustained conservation efforts turtle numbers could continue to increase.

Phylogeography, Genetic Diversity, and Management Units of Hawksbill Turtles in the Indo-Pacific

Hawksbill turtle (Eretmochelys imbricata) populations have experienced global decline because of a history of intense commercial exploitation for shell and stuffed taxidermied whole animals, and harvest for eggs and meat. Improved understanding of genetic diversity and phylogeography is needed to aid conservation. In this study, we analyzed the most geographically comprehensive sample of hawksbill turtles from the Indo-Pacific Ocean, sequencing 766 bp of the mitochondrial control region from 13 locations (plus Aldabra, n = 4) spanning over 13500 km. Our analysis of 492 samples revealed 52 haplotypes distributed in 5 divergent clades. Diversification times differed between the Indo-Pacific and Atlantic lineages and appear to be related to the sea-level changes that occurred during the Last Glacial Maximum. We found signals of demographic expansion only for turtles from the Persian Gulf region, which can be tied to a more recent colonization event. Our analyses revealed evidence of transoceanic migration, including connections between feeding grounds from the Atlantic Ocean and Indo-Pacific rookeries. Hawksbill turtles appear to have a complex pattern of phylogeography, showing a weak isolation by distance and evidence of multiple colonization events. Our novel dataset will allow mixed-stock analyses of hawksbill turtle feeding grounds in the Indo-Pacific by providing baseline data needed for conservation efforts in the region. Eight management units are proposed in our study for the Indo-Pacific region that can be incorporated in conservation plans of this critically endangered species.