23 research outputs found
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 world's 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
Coastal development at sea turtles nesting ground: Efforts to establish a tool for supporting conservation and coastal management in northeastern Brazil
Pivotal temperature and predicted sex ratios for hatchling hawksbill turtles from
Abstract: Like all other species of sea turtle, the hawksbill turtle (Eretmochelys imbricaid) exhibits temperaturedependent sexual differentiation, with high incubation temperatures producing females and low temperatures producing males. Relatively little is known about the sex ratios of hatchlings produced by nesting populations of hawksbill turtles. Here we estimate the overall seasonal sex ratios of hatchling hawksbill turtles produced in Bahia, Brazil, during 6 nesting seasons, based on incubation durations, pivotal temperature, and pivotal incubation duration. The overall sex ratio of hatchlings produced in Bahia fro
Warmer and wetter conditions will reduce offspring production of hawksbill turtles in Brazil under climate change.
Climate change is expected to impact animals that are heavily reliant on environmental factors, such as sea turtles, since the incubation of their eggs, hatching success and sex ratio are influenced by the environment in which eggs incubate. As climate change progresses it is therefore important to understand how climatic conditions influence their reproductive output and the ramifications to population stability. Here, we examined the influences of five climatic variables (air temperature, accumulated and average precipitation, humidity, solar radiation, and wind speed) at different temporal scales on hawksbill sea turtle (Eretmochelys imbricata) hatchling production at ten nesting beaches within two regions of Brazil (five nesting beaches in Rio Grande do Norte and five in Bahia). Air temperature and accumulated precipitation were the main climatic drivers of hawksbill hatching success (number of eggs hatched within a nest) across Brazil and in Rio Grande do Norte, while air temperature and average precipitation were the main climatic drivers of hatching success at Bahia. Solar radiation was the main climatic driver of emergence success (number of hatchlings that emerged from total hatched eggs within a nest) at both regions. Warmer temperatures and higher solar radiation had negative effects on hatchling production, while wetter conditions had a positive effect. Conservative and extreme climate scenarios show air temperatures are projected to increase at this site, while precipitation projections vary between scenarios and regions throughout the 21st century. We predicted hatching success of undisturbed nests (no recorded depredation or storm-related impacts) will decrease in Brazil by 2100 as a result of how this population is influenced by local climate. This study shows the determining effects of different climate variables and their combinations on an important and critically endangered marine species
Data from: First satellite tracks of South Atlantic sea turtle ‘lost years’: seasonal variation in trans-equatorial movement
In the South Atlantic Ocean, few data exist regarding the dispersal of young oceanic sea turtles. We characterized the movements of laboratory-reared yearling loggerhead turtles from Brazilian rookeries using novel telemetry techniques, testing for differences in dispersal during different periods of the sea turtle hatching season that correspond to seasonal changes in ocean currents. Oceanographic drifters deployed alongside satellite-tagged turtles allowed us to explore the mechanisms of dispersal (passive drift or active swimming). Early in the hatching season turtles transited south with strong southward currents. Late in the hatching season, when currents flowed in the opposite direction, turtles uniformly moved northwards across the Equator. However, the movement of individuals differed from what was predicted by surface currents alone. Swimming velocity inferred from track data and an ocean circulation model strongly suggest that turtles' swimming plays a role in maintaining their position within frontal zones seaward of the continental shelf. The long nesting season of adults and behaviour of post-hatchlings exposes young turtles to seasonally varying ocean conditions that lead some individuals further into the South Atlantic and others into the Northern Hemisphere. Such migratory route diversity may ultimately buffer the population against environmental changes or anthropologic threats, fostering population resiliency
Deeper Mitochondrial Sequencing Reveals Cryptic Diversity and Structure in Brazilian Green Turtle Rookeries
Many-to-many mixed stock analysis estimates for Brazilian populations.
<p>(a) shows feeding ground-centric estimates, and (b) rookery-centric estimates. MSA outputs for all other areas are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088746#pone.0088746.s001" target="_blank">Figures S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088746#pone.0088746.s002" target="_blank">S2</a>. BS = Bahia/Sergipe, PI = Pipa, PP = Principe, BB = Barbados, GU = Guadeloupe, AB = Antigua & Barbuda, UV = U.S. Virgin Islands, PR = Puerto Rico, DR = Dominican Republic, CR = Costa Rica, NI = Nicaragua, CU = Cuba, MX = Mexico, SP = São Pedro and São Paulo, CE = Ceará coast, BA = Bahia coast, AP = Abrolhos Park, SB = South Brazil, NR = Noronha/Rocas, PP = Principe, CV = Cape Verde, TC = Turks & Caicos, BH = Bahamas, FL = Florida, CY = Cayman Islands, TX = Texas, FL = Florida, UN = Unknown.</p
Natal origins for <i>E. imbricata</i> in Brazilian waters as estimated by drifters.
<p>SPSP = São Pedro and São Paulo Archipelago; NR/CE = Noronha/Ceará; BA/AP/SB = Bahia, Abrolhos, South Brazil.</p