1
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Arendt MD, Schwenter JA, Owens DW. Climate-mediated population dynamics for the world's most endangered sea turtle species. Sci Rep 2023; 13:14444. [PMID: 37660203 PMCID: PMC10475092 DOI: 10.1038/s41598-023-41647-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 08/29/2023] [Indexed: 09/04/2023] Open
Abstract
Restricted range, and subsequently small population size, render Kemp's ridley sea turtles (Lepidochelys kempii) the most globally endangered sea turtle species. For at least two decades preceding conservation, high egg harvest rates reduced annual cohort recruitment. Despite > 50 years of dedicated conservation, annual nest counts remain well below a landmark 1947 level. Prior studies attribute less robust than anticipated nest count rebound to multiple contemporary concerns; however, analyses herein convey optimistic interpretation. In objective 1, improved analysis of the ratio of hatchlings to nests since 1966 suggested age structure stabilization as a more likely basis for nest count trends after 2005 than density-dependent effects. In objective 2, multiple regression revealed a lagged (≤ 13 years prior) climate influence on nests (adj. r2 = 0.82) and hatchlings per nest (adj. r2 = 0.94) during 2006-2022. In objectives 3 and 4, a simulator modeled population response to changes in a suite of demographic rates including survival. Across 32 models, high survival and dynamic cohort sex ratio, sexual maturity age, and the ratio of clutch frequency to remigration interval best explained nesting trends during 1966-2022. These novel findings provide alternative perspective for evaluating species recovery criteria and in turn refine future nest trend expectations.
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Affiliation(s)
- Michael D Arendt
- South Carolina Department of Natural Resources, Marine Resources Division, 217 Fort Johnson Road, Charleston, SC, 29412, USA.
| | - Jeffrey A Schwenter
- South Carolina Department of Natural Resources, Marine Resources Division, 217 Fort Johnson Road, Charleston, SC, 29412, USA
| | - David W Owens
- College of Charleston, Grice Marine Biology Laboratory (Retired), 205 Fort Johnson Road, Charleston, SC, 29412, USA
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2
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Del Monte-Luna P, Nakamura M, Guzmán-Hernández V, Cuevas E, López-Castro MC, Arreguín-Sánchez F. Multidecadal fluctuations in green turtle hatchling production related to climate variability. Sci Rep 2023; 13:1542. [PMID: 36707700 PMCID: PMC9883438 DOI: 10.1038/s41598-023-28574-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 01/20/2023] [Indexed: 01/28/2023] Open
Abstract
The state of Campeche, Mexico, harbors one of the largest green turtle (Chelonia mydas) rookeries of the Wider Caribbean Region. Since the 1970s, harvesting of this population was common practice, but it has since ceased, and the population is rebounding as a consequence. In this rookery, during the past 37 years (1984-2020), the positive relationship between the annual number of nesting females and the number of hatchlings they produce has revealed a long-term population signal that we postulate could be related to environmental factors. To investigate this relationship more deeply, we adopt a stock-recruitment (SR) approach, which is commonly used in fisheries. Regression analysis methods for the SR relationship, including a dynamic version of the model that incorporates the effect of sea surface temperature, show that the number of recruits produced and the number of hatchlings per unit nester were significantly and inversely correlated with a 26-year cycle of the Atlantic Multidecadal Oscillation (AMO) with a three year lag. A possible explanation for this finding is that environmental conditions during warming periods of the 26-year AMO cycle may negatively affect hatchling production by altering the nest moisture content during the incubation period, and increasing embryonic mortality, while the annual female abundance at nesting beaches may decrease due to trophic effects. The time series of abundance corresponding to other population units of green turtles as well as other species of sea turtles in the Gulf of Mexico present a similar behavior to that evaluated here, suggesting a basin-wide environmental effect.
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Affiliation(s)
- Pablo Del Monte-Luna
- Departamento de Pesquerías y Biología Marina, Instituto Politécnico Nacional, 23096, La Paz, Baja California Sur, Mexico.
| | - Miguel Nakamura
- Departamento de Probabilidad y Estadística, Centro de Investigación en Matemáticas, 36023, Guanajuato, Guanajuato, Mexico.
| | - Vicente Guzmán-Hernández
- Área de Protección de Flora y Fauna Laguna de Términos, Comisión Nacional de Áreas Naturales Protegidas, 24140, Ciudad del Carmen, Campeche, Mexico
| | - Eduardo Cuevas
- Recursos del Mar, CONACYT-Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 97310, Mérida, Yucatán, Mexico
| | - Melania C López-Castro
- Programa para la Conservación de Tortugas Marinas, Pronatura Península de Yucatán, A.C., 97205, Mérida, Yucatán, Mexico
| | - Francisco Arreguín-Sánchez
- Departamento de Pesquerías y Biología Marina, Instituto Politécnico Nacional, 23096, La Paz, Baja California Sur, Mexico
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3
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Putman NF, Richards PM, Dufault SG, Scott-Dention E, McCarthy K, Beyea RT, Caillouet CW, Heyman WD, Seney EE, Mansfield KL, Gallaway BJ. Modeling juvenile sea turtle bycatch risk in commercial and recreational fisheries. iScience 2023; 26:105977. [PMID: 36756371 PMCID: PMC9900512 DOI: 10.1016/j.isci.2023.105977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 11/16/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
Understanding the drivers of fisheries bycatch is essential for limiting its impacts on vulnerable species. Here we present a model to estimate the relative magnitude of sea turtle bycatch in major coastal fisheries across the southeastern US based on spatiotemporal variation in fishing effort and the simulated distributions of juvenile Kemp's ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtles recruiting from oceanic to nearshore habitats. Over the period modeled (1996-2017), bycatch in recreational fisheries was estimated to be greater than the sum of bycatch that occurred in commercial fisheries that have historically been considered high risks to turtles (e.g., those using trawls, gillnets, and bottom longlines). Prioritizing engagement with recreational anglers to reduce bycatch could be especially beneficial to sea turtle populations. Applying lessons learned from efforts to protect turtles in commercial fisheries may help meet the challenges that arise from the large, diffuse recreational fishing sector.
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Affiliation(s)
- Nathan F. Putman
- LGL Ecological Research Associates, Bryan, TX 77802, USA,Corresponding author
| | - Paul M. Richards
- NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Miami, FL 33149, USA
| | | | - Elizabeth Scott-Dention
- NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Galveston, TX 77551, USA
| | - Kevin McCarthy
- NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Miami, FL 33149, USA
| | | | | | | | - Erin E. Seney
- Marine Turtle Research Group, Department of Biology, University of Central Florida, Orlando, FL 32816, USA
| | - Katherine L. Mansfield
- Marine Turtle Research Group, Department of Biology, University of Central Florida, Orlando, FL 32816, USA
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4
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The secret life of baby turtles: A novel system to predict hatchling emergence, detect infertile nests, and remotely monitor sea turtle nest events. PLoS One 2022; 17:e0275088. [PMID: 36288397 PMCID: PMC9605334 DOI: 10.1371/journal.pone.0275088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 09/09/2022] [Indexed: 11/19/2022] Open
Abstract
Current understanding of sea turtle nesting, hatching, and emergence events has been largely limited to observable events on the surface of the sand, though recent approaches using audio or visual equipment have allowed scientists to better understand some underground nest phenomena. We used a technology-based approach to define motion-related Caretta caretta hatching and emergence nest events. We describe a novel low-cost, accelerometer-based system called TurtleSense that can detect movement and temperature within sea turtle nests remotely. TurtleSense is successfully able to specifically detect motion within sea turtle nests over the entire course of incubation. This system allows for the identification of infertile nests and the detection of four predictable sequential developmental activity patterns in viable nests, including a hatch and posthatch period, the timing of which can be used to tightly predict hatchling emergence events almost to the day. TurtleSense provides a much better understanding about what is happening in the nest before emergence and allows for the generation of a theory of the mechanism that triggers mass emergence. Our results suggest that motion plays a large role in hatchling communication and that the timing of emergence events may be related to the cessation of movement within the nest. Current management of sea turtle nesting events is primarily driven by counting the number of days since the nest was laid, with further safeguards placed at the nest upon subsequent visual observation of depression or emergence events. Use of TurtleSense technology can impact nest management and conservation efforts, allowing organizations to use this motion data to more tightly predict emergence dates for sea turtle hatchlings and to use viability data to inform nest management decisions.
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5
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Kettemer LE, Biastoch A, Wagner P, Coombs EJ, Penrose R, Scott R. Oceanic drivers of juvenile sea turtle strandings in the UK. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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6
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Horton KG, Van Doren BM, Albers HJ, Farnsworth A, Sheldon D. Near-term ecological forecasting for dynamic aeroconservation of migratory birds. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2021; 35:1777-1786. [PMID: 33826183 PMCID: PMC9290813 DOI: 10.1111/cobi.13740] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/06/2021] [Accepted: 03/12/2021] [Indexed: 05/08/2023]
Abstract
Near-term ecological forecasting has the potential to mitigate negative impacts of human modifications on wildlife by directing efficient action through relevant and timely predictions. We used the U.S. avian migration system to highlight ecological forecasting applications for aeroconservation. We used millions of observations from 143 weather surveillance radars to construct and evaluate a migration forecasting system for nocturnal bird migration over the contiguous United States. We identified the number of nights of mitigation required to reduce the risk of aerial hazards to 50% of avian migrants passing a given area in spring and autumn based on dynamic forecasts of migration activity. We also investigated an alternative approach, that is, employing a fixed conservation strategy based on time windows that historically capture 50% of migratory passage. In practice, during both spring and autumn, dynamic forecasts required fewer action nights compared with fixed window selection at all locations (spring: mean of 7.3 more alert days; fall: mean of 12.8 more alert days). This pattern resulted in part from the pulsed nature of bird migration captured in the radar data, where the majority (54.3%) of birds move on 10% of a migration season's nights. Our results highlight the benefits of near-term ecological forecasting and the potential advantages of dynamic mitigation strategies over static ones, especially in the face of increasing risks to migrating birds from light pollution, wind energy infrastructure, and collisions with structures.
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Affiliation(s)
- Kyle G. Horton
- Department of Fish, Wildlife, and Conservation BiologyColorado State UniversityFort CollinsColoradoUSA
| | - Benjamin M. Van Doren
- Edward Grey Institute, Department of ZoologyUniversity of OxfordOxfordUK
- Cornell Lab of OrnithologyCornell UniversityIthacaNew YorkUSA
| | - Heidi J. Albers
- Department of EconomicsUniversity of WyomingLaramieWyomingUSA
| | | | - Daniel Sheldon
- College of Information and Computer SciencesUniversity of MassachusettsAmherstMassachusettsUSA
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7
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Arendt MD, Schwenter JA, Owens DW, Valverde RA. Theoretical modeling and neritic monitoring of loggerhead Caretta caretta [Linnaeus, 1758] sea turtle sex ratio in the southeast United States do not substantiate fears of a male-limited population. GLOBAL CHANGE BIOLOGY 2021; 27:4849-4859. [PMID: 34273224 PMCID: PMC9291020 DOI: 10.1111/gcb.15808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Sea turtles are among several hundred species whose sex is determined by incubation conditions during critical developmental periods. Consequently, these marine reptiles may be vulnerable to global climate change, and under the assumption of continued climate warming, numerous studies pose dire predictions for future populations based primarily on hatchling sex ratio data. Alternatively, as long-lived species that take decades to reach maturity, without inherent coping mechanisms for such change, sea turtles could not have persisted across geological epochs. Globally, loggerhead Caretta caretta [Linnaeus, 1758] sea turtles occupy temperate zones, with ontogenetic development that spans the entirety of gyres associated with respective ocean basins. The largest rookery for this species occurs in the Northwest Atlantic Ocean (NWA) population, where a 30-year cycle in annual nest counts is reported through 2018. Complementary studies document a lagged association between these annual nest counts and the Atlantic Multidecadal Oscillation (AMO); however, the underlying mechanism for this association remains elusive. Therefore, objective 1 evaluated the effect of AMO-mediated cohort resonance on the demographic structure of a theoretical neritic assemblage under variable cohort abundance and female proportion but stable annual survival during 165-year runs (i.e., extent of AMO data). For objective 2, blood samples were used to assign sex to 2217 loggerhead sea turtles captured by research trawling (2000 to 2019) on the inner continental shelf from St. Augustine, FL (29.9°N) to Winyah Bay, SC (33.1°N). Shorter oceanic duration of less female-biased cohorts from the AMO cold phase synchronized peak adult male and adult female co-occurrence during subsequent warm phases three decades later. Grand sex ratio predicted from testosterone was 67% female (n = 1484), with a slight temporal female decline. Our findings suggest greater population sex ratio plasticity than predicted solely from terrestrial nesting data.
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Affiliation(s)
- Michael D. Arendt
- Marine Resources DivisionSouth Carolina Department of Natural ResourcesCharlestonSCUSA
| | - Jeffrey A. Schwenter
- Marine Resources DivisionSouth Carolina Department of Natural ResourcesCharlestonSCUSA
| | - David W. Owens
- Grice Marine LaboratoryCollege of CharlestonCharlestonSCUSA
| | - Roldán A. Valverde
- Department of Biological SciencesSoutheastern Louisiana UniversityHammondLAUSA
- Sea Turtle ConservancyGainesvilleFLUSA
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8
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Shamblott KM, Reneker JL, Kamel SJ. The thermal impacts of beach nourishment across a regionally important loggerhead sea turtle (
Caretta caretta
) rookery. Ecosphere 2021. [DOI: 10.1002/ecs2.3396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Kaitlynn M. Shamblott
- Department of Biology and Marine Biology Center for Marine Science University of North Carolina Wilmington Wilmington North Carolina28409USA
| | | | - Stephanie J. Kamel
- Department of Biology and Marine Biology Center for Marine Science University of North Carolina Wilmington Wilmington North Carolina28409USA
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9
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Cassill DL. Multiple maternal risk-management adaptations in the loggerhead sea turtle (Caretta caretta) mitigate clutch failure caused by catastrophic storms and predators. Sci Rep 2021; 11:2491. [PMID: 33510318 PMCID: PMC7844227 DOI: 10.1038/s41598-021-81968-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 01/11/2021] [Indexed: 01/30/2023] Open
Abstract
Maternal risk-management, an extension of r/K selection, is an indispensable tool for understanding the natural selection pressures that shape the evolution of reproduction. Central to the construct of maternal risk-management is its definition of reproductive success as replacement fitness (w = 2), the survival of one breeding daughter to replace the female and one outbreeding son to replace her mate. Here, I apply maternal risk-management as a theoretical framework to explain multiple reproductive adaptations by loggerhead sea turtles nesting on a barrier island off the southern coast of Florida, US, from 1988 to 2004. Extrapolated over a 30-year reproductive span, nesting females averaged 4000-4500 eggs. I show that, rather than "putting all their eggs in one basket," females divided eggs into 40 clutches of variable size (50-165 eggs). To deposit clutches, females migrated to the barrier island 10-12 times at unpredictable intervals of 2-8 years. Each nesting season, females deposited 1-7 clutches over diversified time intervals at diversified locations on the beach. Despite devastating clutch losses caused by ten catastrophic hurricanes, hundreds of erratic thunderstorms and dozens of predation events during this study, 72% of clutches produced by nesting females on this barrier island were undisturbed-median hatching success for these clutches was an astonishing 92%. I conclude that diversified maternal investments over time and space by nesting females are reproductive adaptations that have successfully offset clutch losses, thus enabling populations of loggerhead females to meet or exceed their reproductive goal of replacement fitness.
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Affiliation(s)
- Deby L. Cassill
- grid.170693.a0000 0001 2353 285XDepartment of Integrative Biology, USF, St. Petersburg campus, St. Petersburg, FL 33701 USA
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10
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Mashkour N, Jones K, Kophamel S, Hipolito T, Ahasan S, Walker G, Jakob-Hoff R, Whittaker M, Hamann M, Bell I, Elliman J, Owens L, Saladin C, Crespo-Picazo JL, Gardner B, Loganathan AL, Bowater R, Young E, Robinson D, Baverstock W, Blyde D, March D, Eghbali M, Mohammadi M, Freggi D, Giliam J, Hale M, Nicolle N, Spiby K, Wrobel D, Parga M, Mobaraki A, Rajakaruna R, Hyland KP, Read M, Ariel E. Disease risk analysis in sea turtles: A baseline study to inform conservation efforts. PLoS One 2020; 15:e0230760. [PMID: 33095793 PMCID: PMC7584443 DOI: 10.1371/journal.pone.0230760] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/16/2020] [Indexed: 12/03/2022] Open
Abstract
The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and "One Health" aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.
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Affiliation(s)
- Narges Mashkour
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Karina Jones
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
- College of Medicine and Dentistry, James Cook University, Townsville, Australia
| | - Sara Kophamel
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Teresa Hipolito
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Shamim Ahasan
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
- Faculty of Veterinary and Animal Science, Hajee Mohammad Danesh Science & Technology University, Dinjapur, Rangpur, Bangladesh
| | - Grant Walker
- North East Sea Turtles, Charlotteville, Tobago, Trinidad and Tobago
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland
| | - Richard Jakob-Hoff
- New Zealand Centre for Conservation Medicine, Auckland Zoo, Auckland, New Zealand
- School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Australia
| | - Maxine Whittaker
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Mark Hamann
- College of Science and Engineering, James Cook University, Townsville, Australia
| | - Ian Bell
- Faculty of Health and Behavioural Sciences, University of Queensland, Brisbane, Australia
| | - Jennifer Elliman
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Leigh Owens
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Claire Saladin
- Reserve Naturelle de Saint Barthelemy, Gustavia, Saint Barthelemy
- FWI/Reserve Naturelle de Saint Martin, Saint Martin, French West Indies
| | - Jose Luis Crespo-Picazo
- Veterinary Services & Research Department, Fundación Oceanogràfic, Avanqua Oceanogràfic-Ágora, Valencia, Spain
| | - Brett Gardner
- Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia
- Two Oceans Aquarium, Cape Town, South Africa
| | | | - Rachel Bowater
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
| | - Erina Young
- Conservation Medicine Program School of Veterinary and Life Sciences, College of Veterinary Medicine Murdoch University, Perth, Western Australia
| | - David Robinson
- The Aquarium & Dubai Turtle Rehabilitation Project, Burj Al Arab, Dubai, United Arab Emirates
| | - Warren Baverstock
- The Aquarium & Dubai Turtle Rehabilitation Project, Burj Al Arab, Dubai, United Arab Emirates
| | - David Blyde
- Sea World, Gold Coast, Queensland, Australia
| | - Duan March
- National Marine Science Centre & Centre for Coastal Biogeochemistry Research, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, NSW, Australia
- Dolphin Marine Rescue Animal Rehab Trust, Coffs Harbour, New South Wales, Australia
| | - Maryam Eghbali
- Ideh no doostdar_E- Hormozgan Ecotourism and NGO group, Iran
| | | | | | - Jane Giliam
- The Ark Animal Hospital, Northern Territory, Australia
| | - Mike Hale
- Yuku Baja Muliku Ranger Base, Archer Point, Australia
| | | | - Kevin Spiby
- Two Oceans Aquarium, Cape Town, South Africa
| | - Daphne Wrobel
- Fundação Pró-TAMAR, Rua Professor Ademir Francisco s/n–Barra da Lagoa, Florianópolis–SC, Brazil
| | - Mariluz Parga
- SUBMON—Marine Environmental Services, Barcelona, Spain
| | - Asghar Mobaraki
- Department of the Environment, Wildlife and Aquatic Affairs Bureau, Tehran, Iran
| | | | | | - Mark Read
- Field Management Unit, Great Barrier Reef Marine Park Authority, Queensland, Australia
| | - Ellen Ariel
- College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Australia
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11
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Charitonidou M, Stara K, Kougioumoutzis K, Halley JM. Implications of salep collection for the conservation of the Elder-flowered orchid ( Dactylorhiza sambucina) in Epirus, Greece. ACTA ACUST UNITED AC 2019; 26:18. [PMID: 31893195 PMCID: PMC6936056 DOI: 10.1186/s40709-019-0110-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/19/2019] [Indexed: 11/22/2022]
Abstract
Background In Epirus, Greece, orchids have been traditionally harvested for the production of salep, a beverage made from their tubers. Over-collection of orchids for salep is believed to be a growing threat to wild species, yet very little research has concentrated on orchid populations in the wild. Here, we studied the impact of salep collection on population demographic parameters and uniformity of distribution patterns of the Elder-flowered orchid, Dactylorhiza sambucina, the most commonly collected orchid in northern Greece. Methods We carried out fieldwork in four meadows where salep harvesting occurs, and conducted interviews in villages close to these sites. Fieldwork focused on the demographic parameters of orchid populations and on the characteristics of their habitat (natural-anthropogenic). We also measured population size and distribution, extent and multi-scale density, comparing distributions to Poisson and fractal models. Results According to interviews, salep collection by the local community has decreased, contrary to collection by people outside the community, which is increasing. Interviewees did not believe that orchid abundance was higher in the past; they claim that it can be very variable. None of the participants seemed aware of the legislation to conserve orchids. Demographic parameters did not seem to be strongly dependent on whether it was a harvested and non-harvested sites and population density was greatest in the site of highest collection pressure. Conclusions Our findings show that salep collection is still ongoing in Epirus. Our interview results and our population study indicate that current levels of collection are not significantly affecting the abundance of the Elder-flowered orchid in Epirus subalpine meadows. However, the expanding commercial collection could reach levels that threaten the species. There is a need for a longer-term monitoring of these orchid populations, and a more effective modeling of the species’ response to different harvesting pressures.
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Affiliation(s)
- Martha Charitonidou
- 1Laboratory of Ecology, Department of Biological Applications & Technology, University of Ioannina, 45110 Ioannina, Greece
| | - Kalliopi Stara
- 1Laboratory of Ecology, Department of Biological Applications & Technology, University of Ioannina, 45110 Ioannina, Greece
| | - Konstantinos Kougioumoutzis
- 1Laboratory of Ecology, Department of Biological Applications & Technology, University of Ioannina, 45110 Ioannina, Greece.,2Department of Ecology and Systematics, Faculty of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece
| | - John M Halley
- 1Laboratory of Ecology, Department of Biological Applications & Technology, University of Ioannina, 45110 Ioannina, Greece
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12
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Ceriani SA, Casale P, Brost M, Leone EH, Witherington BE. Conservation implications of sea turtle nesting trends: elusive recovery of a globally important loggerhead population. Ecosphere 2019. [DOI: 10.1002/ecs2.2936] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- S. A. Ceriani
- Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute Saint Petersburg Florida 33701 USA
| | - P. Casale
- Department of Biology University of Pisa Pisa Italy
| | - M. Brost
- Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute Saint Petersburg Florida 33701 USA
| | - E. H. Leone
- Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute 1105 SW Williston Road Gainesville Florida 32601 USA
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13
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Relative abundance of oceanic juvenile loggerhead sea turtles in relation to nest production at source rookeries: implications for recruitment dynamics. Sci Rep 2019; 9:13019. [PMID: 31506566 PMCID: PMC6737082 DOI: 10.1038/s41598-019-49434-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/23/2019] [Indexed: 11/08/2022] Open
Abstract
After hatching, juveniles of most sea turtle species undertake long migrations across ocean basins and remain in oceanic habitats for several years. Assessing population abundance and demographic parameters during this oceanic stage is challenging. Two long-recognized deficiencies in population assessment are (i) reliance on trends in numbers of nests or reproductive females at nesting beaches and (ii) ignorance of factors regulating recruitment to the early oceanic stage. To address these critical gaps, we examined 15 years of standardized loggerhead sighting data collected opportunistically by fisheries observers in the Azores archipelago. From 2001 to 2015, 429 loggerheads were sighted during 67,922 km of survey effort. We used a model-based approach to evaluate the influence of environmental factors and present the first estimates of relative abundance of oceanic-stage juvenile sea turtles. During this period, relative abundance of loggerheads in the Azores tracked annual nest abundance at source rookeries in Florida when adjusted for a 3-year lag. This concurrence of abundance patterns indicates that recruitment to the oceanic stage is more dependent on nest abundance at source rookeries than on stochastic processes derived from short term climatic variability, as previously believed.
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Becker SL, Brainard RE, Van Houtan KS. Densities and drivers of sea turtle populations across Pacific coral reef ecosystems. PLoS One 2019; 14:e0214972. [PMID: 31017916 PMCID: PMC6481790 DOI: 10.1371/journal.pone.0214972] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 03/24/2019] [Indexed: 11/18/2022] Open
Abstract
Sea turtle populations are often assessed at the regional to sub-basin scale from discrete indices of nesting abundance. While this may be practical and sometimes effective, widespread in-water surveys may enhance assessments by including additional demographics, locations, and revealing emerging population trends. Here, we describe sea turtle observations from 13 years of towed-diver surveys across 53 coral islands, atolls, and reefs in the Central, West, and South Pacific. These surveys covered more than 7,300 linear km, and observed more than 3,400 green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles. From these data, we estimated sea turtle densities, described trends across space and time, and modelled the influence of environmental and anthropogenic drivers. Both species were patchily distributed across spatial scales, and green turtles were 11 times more abundant than hawksbills. The Pacific Remote Island Areas had the highest densities of greens (3.62 turtles km-1, Jarvis Island), while American Samoa had the most hawksbills (0.12 turtles km-1, Ta'u Island). The Hawaiian Islands had the lowest turtle densities (island ave = 0.07 turtles km-1) yet the highest annual population growth (μ = 0.08, σ = 0.22), suggesting extensive management protections can yield positive conservation results. Densities peaked at 27.5°C SST, in areas of high productivity and low human impact, and were consistent with patterns of historic overexploitation. Though such intensive surveys have great value, they are logistically demanding and therefore have an uncertain budget and programmatic future. We hope the methods we described here may be applied to future comparatively low-cost surveys either with autonomous vehicles or with environmental DNA.
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Affiliation(s)
- Sarah L. Becker
- Monterey Bay Aquarium, Monterey, California, United States of America
- * E-mail:
| | - Russell E. Brainard
- NOAA Pacific Islands Fisheries Science Center, Ecosystem Sciences Division, Honolulu, Hawaii United States of America
| | - Kyle S. Van Houtan
- Monterey Bay Aquarium, Monterey, California, United States of America
- Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina United States of America
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15
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Valdivia A, Wolf S, Suckling K. Marine mammals and sea turtles listed under the U.S. Endangered Species Act are recovering. PLoS One 2019; 14:e0210164. [PMID: 30650125 PMCID: PMC6334928 DOI: 10.1371/journal.pone.0210164] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 12/18/2018] [Indexed: 11/24/2022] Open
Abstract
The U.S. Endangered Species Act (ESA) is a powerful environmental law protecting imperiled plants and animals, and a growing number of marine species have been protected under this law as extinction risk in the oceans has increased. Marine mammals and sea turtles comprise 38% of the 163 ESA-listed marine "species", which includes subspecies and distinct population segments, yet analyses of recovery trends after listing are lacking. Here we gathered the best available annual abundance estimates for geographically delimited populations of all 62 marine mammal and sea turtle species listed under the ESA. Of these, we chose representative populations of species that were listed before 2012, occur and reproduce in U.S. waters, and have data of sufficient quality and timespan for trend analyses. Thus, we quantitatively analyzed population trends, magnitude of population change, and recovery status for 23 and 8 representative populations of 14 marine mammal and 5 sea turtle species, respectively. Using generalized linear and non-linear models, we found that 18 marine mammal (78%) and 6 sea turtle (75%) populations significantly increased after listing; 3 marine mammal (13%) and 2 sea turtle (25%) populations showed non-significant changes; while 2 marine mammal (9%), but no sea turtle populations declined after ESA protection. Overall, the 24 populations that increased in abundance were from species listed for 20 years or more (e.g., large whales, manatees, and sea turtles). Conservation measures triggered by ESA listing such as ending exploitation, tailored species management, and fishery regulations, and other national and international measures, appear to have been largely successful in promoting species recovery, leading to the delisting of some species and to increases in most populations. These findings underscore the capacity of marine mammal and sea turtle species to recover from substantial geographical population declines when conservation actions are implemented in a timely and effective manner.
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Affiliation(s)
- Abel Valdivia
- Center for Biological Diversity, Oakland, California, United States of America
| | - Shaye Wolf
- Center for Biological Diversity, Oakland, California, United States of America
| | - Kieran Suckling
- Center for Biological Diversity, Tucson, Arizona, United States of America
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16
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Halley JM, Van Houtan KS, Mantua N. How survival curves affect populations' vulnerability to climate change. PLoS One 2018; 13:e0203124. [PMID: 30188919 PMCID: PMC6126862 DOI: 10.1371/journal.pone.0203124] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 08/15/2018] [Indexed: 11/19/2022] Open
Abstract
Human activities are exposing organisms not only to direct threats (e.g. habitat loss) but also to indirect environmental pressures such as climate change, which involves not just directional global warming but also increasing climatic variability. Such changes will impact whole communities of organisms and the possible effects on population dynamics have raised concerns about increased extinction rates. Conservation-minded approaches to extinction risk vary from range shifts predicted by climate envelope models with no population dynamics to population viability analyses that ignore environmental variability altogether. Our modelling study shows that these extremes are modelling responses to a spectrum of environmental sensitivity that organisms may exhibit. We show how the survival curve plays a major role in how environmental variability leads to population fluctuations. While it is often supposed that low-fecundity organisms (those with high parental investment) will be the most vulnerable to climate change, it is those with high fecundity (low parental investment) that are likely to be more sensitive to such changes. We also find that abundance variations in high fecundity populations is driven primarily by fluctuations in the survival of early life stages, the more so if those environmental changes are autocorrelated in time. We show which types of conservation actions are most appropriate for a number of real populations. While the most effective conservation actions for organisms of low fecundity is to avoid killing them, for populations with high fecundity (and low parental investment), our study suggests conservation should focus more on protecting early life stages from hostile environments.
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Affiliation(s)
- John M. Halley
- Department of Biological Applications and Technology, School of Health Sciences, University of Ioannina, Ioannina, Greece
- * E-mail:
| | - Kyle S. Van Houtan
- Monterey Bay Aquarium, Monterey, CA, United States of America
- Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, United States of America
| | - Nate Mantua
- NOAA Fisheries, Southwest Fisheries Science Center, Santa Cruz, California, United States of America
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17
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Briscoe DK, Parker DM, Balazs GH, Kurita M, Saito T, Okamoto H, Rice M, Polovina JJ, Crowder LB. Active dispersal in loggerhead sea turtles (Caretta caretta) during the 'lost years'. Proc Biol Sci 2017; 283:rspb.2016.0690. [PMID: 27252021 DOI: 10.1098/rspb.2016.0690] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/09/2016] [Indexed: 11/12/2022] Open
Abstract
Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their 'lost years' at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1-3 year old turtles released off Japan (29.7-37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.
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Affiliation(s)
- D K Briscoe
- Biology, Stanford University, Hopkins Marine Station, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA
| | - D M Parker
- Joint Institute for Marine and Atmospheric Research, National Oceanic and Atmospheric Administration, 2032 Southeast Oregon State University Drive, Newport, OR 97365, USA
| | - G H Balazs
- Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration Inouye Regional Center, National Marine Fisheries Service, 1845 WASP Boulevard Building 176, Honolulu, HI 96818, USA
| | - M Kurita
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - T Saito
- Usa Marine Biological Institute, Kochi University, Usa Tosa, Kochi 781-1164, Japan
| | - H Okamoto
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - M Rice
- Hawaii Preparatory Academy, 65-1692 Kohala Mountain Road, Kamuela, HI 96743, USA
| | - J J Polovina
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - L B Crowder
- Biology, Stanford University, Hopkins Marine Station, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA Center for Ocean Solutions, Stanford University, 99 Pacific Street, Suite 555E, Monterey, CA 93949, USA
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18
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Marn N, Jusup M, Legović T, Kooijman S, Klanjšček T. Environmental effects on growth, reproduction, and life-history traits of loggerhead turtles. Ecol Modell 2017. [DOI: 10.1016/j.ecolmodel.2017.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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Azanza-Ricardo J, Martín MEI, Sansón GG, Harrison E, Cruz YM, Bretos F. Possible Effect of Global Climate Change onCaretta caretta(Testudines, Cheloniidae) Nesting Ecology at Guanahacabibes Peninsula, Cuba. CHELONIAN CONSERVATION AND BIOLOGY 2017. [DOI: 10.2744/ccb-1241.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Julia Azanza-Ricardo
- Instituto Superior de Tecnología y Ciencias Aplicadas, CP 10400, Ciudad Habana, Cuba []
- Centro de Investigaciones Marinas, Universidad de La Habana. Calle 16 No. 114 e/1ra y 3ra, Playa, CP 11300, Ciudad Habana, Cuba
| | - María E. Ibarra Martín
- Centro de Investigaciones Marinas, Universidad de La Habana. Calle 16 No. 114 e/1ra y 3ra, Playa, CP 11300, Ciudad Habana, Cuba
| | - Gaspar González Sansón
- Centro de Investigaciones Marinas, Universidad de La Habana. Calle 16 No. 114 e/1ra y 3ra, Playa, CP 11300, Ciudad Habana, Cuba
- Departamento de Estudios para el Desarrollo Sustentable de Zonas Costeras, Universidad de Guadalajara, Gómez Farías 82, San Patricio-Melaque, Cihuatlán, Jalisco, CP 48980 []
| | | | | | - Fernando Bretos
- Cuba Marine Research & Conservation, Patricia and Phillip Frost Museum of Science, 3280 South Miami Avenue, Miami, Florida 33129 USA []
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20
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Marn N, Kooijman SALM, Jusup M, Legović T, Klanjšček T. Inferring physiological energetics of loggerhead turtle (Caretta caretta) from existing data using a general metabolic theory. MARINE ENVIRONMENTAL RESEARCH 2017; 126:14-25. [PMID: 28219019 DOI: 10.1016/j.marenvres.2017.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/18/2017] [Accepted: 01/19/2017] [Indexed: 05/14/2023]
Abstract
Loggerhead turtle is an endangered sea turtle species with a migratory lifestyle and worldwide distribution, experiencing markedly different habitats throughout its lifetime. Environmental conditions, especially food availability and temperature, constrain the acquisition and the use of available energy, thus affecting physiological processes such as growth, maturation, and reproduction. These physiological processes at the population level determine survival, fecundity, and ultimately the population growth rate-a key indicator of the success of conservation efforts. As a first step towards the comprehensive understanding of how environment shapes the physiology and the life cycle of a loggerhead turtle, we constructed a full life cycle model based on the principles of energy acquisition and utilization embedded in the Dynamic Energy Budget (DEB) theory. We adapted the standard DEB model using data from published and unpublished sources to obtain parameter estimates and model predictions that could be compared with data. The outcome was a successful mathematical description of ontogeny and life history traits of the loggerhead turtle. Some deviations between the model and the data existed (such as an earlier age at sexual maturity and faster growth of the post-hatchlings), yet probable causes for these deviations were found informative and discussed in great detail. Physiological traits such as the capacity to withstand starvation, trade-offs between reproduction and growth, and changes in the energy budget throughout the ontogeny were inferred from the model. The results offer new insights into physiology and ecology of loggerhead turtle with the potential to lead to novel approaches in conservation of this endangered species.
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Affiliation(s)
- Nina Marn
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia.
| | - S A L M Kooijman
- Vrije Universiteit Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
| | - Marko Jusup
- Center of Mathematics for Social Creativity, Hokkaido University, 12-7 Kita Ward, 060-0812 Sapporo, Japan.
| | - Tarzan Legović
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia
| | - Tin Klanjšček
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia
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21
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Ascani F, Van Houtan KS, Di Lorenzo E, Polovina JJ, Jones TT. Juvenile recruitment in loggerhead sea turtles linked to decadal changes in ocean circulation. GLOBAL CHANGE BIOLOGY 2016; 22:3529-3538. [PMID: 27126518 DOI: 10.1111/gcb.13331] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 04/05/2016] [Accepted: 04/05/2016] [Indexed: 06/05/2023]
Abstract
Given the threats of climate change, understanding the relationship of climate with long-term population dynamics is critical for wildlife conservation. Previous studies have linked decadal climate oscillations to indices of juvenile recruitment in loggerhead sea turtles (Caretta caretta), but without a clear understanding of mechanisms. Here, we explore the underlying processes that may explain these relationships. Using the eddy-resolving Ocean General Circulation Model for the Earth Simulator, we generate hatch-year trajectories for loggerhead turtles emanating from Japan over six decades (1950-2010). We find that the proximity of the high-velocity Kuroshio Current to the primary nesting areas in southern Japan is remarkably stable and that hatchling dispersal to oceanic habitats itself does not vary on decadal timescales. However, we observe a shift in latitudes of trajectories, consistent with the Pacific Decadal Oscillation (PDO). In a negative PDO phase, the Kuroshio Extension Current (KEC) is strong and acts as a physical barrier to the northward transport of neonates. As a result, hatch-year trajectories remain mostly below 35°N in the warm, unproductive region south of the Transition Zone Chlorophyll Front (TZCF). During a positive PDO phase, however, the KEC weakens facilitating the neonates to swim north of the TZCF into cooler and more productive waters. As a result, annual cohorts from negative PDO years may face a lack of resources, whereas cohorts from positive PDO years may find sufficient resources during their pivotal first year. These model outputs indicate that the ocean circulation dynamics, combined with navigational swimming behavior, may be a key factor in the observed decadal variability of sea turtle populations.
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Affiliation(s)
- François Ascani
- Pacific Islands Fisheries Science Center, NOAA Fisheries, 1845 Wasp Boulevard, Building 176, Honolulu, HI, 96818, USA.
| | - Kyle S Van Houtan
- Pacific Islands Fisheries Science Center, NOAA Fisheries, 1845 Wasp Boulevard, Building 176, Honolulu, HI, 96818, USA
- Nicholas School of the Environment and Earth Sciences, Duke University, 450 Research Drive, Durham, NC, 27708, USA
| | - Emanuele Di Lorenzo
- School of Earth & Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive Atlanta, Atlanta, GA, 30332-0340, USA
| | - Jeffrey J Polovina
- Pacific Islands Fisheries Science Center, NOAA Fisheries, 1845 Wasp Boulevard, Building 176, Honolulu, HI, 96818, USA
| | - T Todd Jones
- Pacific Islands Fisheries Science Center, NOAA Fisheries, 1845 Wasp Boulevard, Building 176, Honolulu, HI, 96818, USA
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22
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Van Houtan KS, Francke DL, Alessi S, Jones TT, Martin SL, Kurpita L, King CS, Baird RW. The developmental biogeography of hawksbill sea turtles in the North Pacific. Ecol Evol 2016; 6:2378-89. [PMID: 27110350 PMCID: PMC4834323 DOI: 10.1002/ece3.2034] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/30/2016] [Accepted: 02/04/2016] [Indexed: 12/14/2022] Open
Abstract
High seas oceanic ecosystems are considered important habitat for juvenile sea turtles, yet much remains cryptic about this important life‐history period. Recent progress on climate and fishery impacts in these so‐called lost years is promising, but the developmental biogeography of hawksbill sea turtles (Eretmochelys imbricata) has not been widely described in the Pacific Ocean. This knowledge gap limits the effectiveness of conservation management for this globally endangered species. We address this with 30 years of stranding observations, 20 years of bycatch records, and recent simulations of natal dispersal trajectories in the Hawaiian Archipelago. We synthesize the analyses of these data in the context of direct empirical observations, anecdotal sightings, and historical commercial harvests from the insular Pacific. We find hawksbills 0–4 years of age, measuring 8–34 cm straight carapace length, are found predominantly in the coastal pelagic waters of Hawaii. Unlike other species, we find no direct evidence of a prolonged presence in oceanic habitats, yet satellite tracks of passive drifters (simulating natal dispersal) and our small sample sizes suggest that an oceanic phase for hawksbills cannot be dismissed. Importantly, despite over 600 million hooks deployed and nearly 6000 turtle interactions, longline fisheries have never recorded a single hawksbill take. We address whether the patterns we observe are due to population size and gear selectivity. Although most sea turtle species demonstrate clear patterns of oceanic development, hawksbills in the North Pacific may by contrast occupy a variety of ecosystems including coastal pelagic waters and shallow reefs in remote atolls. This focuses attention on hazards in these ecosystems – entanglement and ingestion of marine debris – and perhaps away from longline bycatch and decadal climate regimes that affect sea turtle development in oceanic regions.
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Affiliation(s)
- Kyle S Van Houtan
- NOAA Fisheries Pacific Islands Fisheries Science Center Honolulu Hawaii 96818; Nicholas School of the Environment Duke University Durham North Carolina 27708; Present address: Monterey Bay Aquarium Monterey California 93940
| | - Devon L Francke
- Joint Institute for Marine and Atmospheric Research University of Hawaii Honolulu Hawaii 96822
| | - Sarah Alessi
- Joint Institute for Marine and Atmospheric Research University of Hawaii Honolulu Hawaii 96822
| | - T Todd Jones
- NOAA Fisheries Pacific Islands Fisheries Science Center Honolulu Hawaii 96818
| | - Summer L Martin
- National Research Council National Academy of Sciences Washington District of Columbia 20001
| | - Lauren Kurpita
- Pacific Cooperative Studies Unit University of Hawaii Honolulu Hawaii 96822; World Turtle Trust Kailua Hawaii 96734
| | | | - Robin W Baird
- Cascadia Research Collective Olympia Washington 98501
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23
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Van Houtan KS, Halley JM, Marks W. Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns. Biol Lett 2015; 11:20140744. [PMID: 25589483 DOI: 10.1098/rsbl.2014.0744] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Naturalists as early as Darwin observed terrestrial basking in green turtles (Chelonia mydas), but the distribution and environmental influences of this behaviour are poorly understood. Here, we examined 6 years of daily basking surveys in Hawaii and compared them with the phenology of local sea surface temperatures (SST). Data and models indicated basking peaks when SST is coolest, and we found this timeline consistent with bone stress markings. Next, we assessed the decadal SST profiles for the 11 global green turtle populations. Basking generally occurs when winter SST falls below 23°C. From 1990 to 2014, the SST for these populations warmed an average 0.04°C yr(-1) (range 0.01-0.09°C yr(-1)); roughly three times the observed global average over this period. Owing to projected future warming at basking sites, we estimated terrestrial basking in green turtles may cease globally by 2100. To predict and manage for future climate change, we encourage a more detailed understanding for how climate influences organismal biology.
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Affiliation(s)
- Kyle S Van Houtan
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Honolulu, HI 96818, USA Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
| | - John M Halley
- Department of Biological Applications and Technology, University of Ioannina, 451 10 Ioannina, Greece
| | - Wendy Marks
- NOAA Fisheries, Pacific Islands Fisheries Science Center, Honolulu, HI 96818, USA
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24
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Tomaszewicz CNT, Seminoff JA, Avens L, Goshe LR, Peckham SH, Rguez-Baron JM, Bickerman K, Kurle CM. Age and residency duration of loggerhead turtles at a North Pacific bycatch hotspot using skeletochronology. BIOLOGICAL CONSERVATION 2015; 186:134-142. [PMID: 25848136 PMCID: PMC4384431 DOI: 10.1016/j.biocon.2015.03.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For migratory marine animals, like sea turtles, effective conservation can be challenging because key demographic information such as duration of life stages and exposure to spatially explicit threats in different habitats are often unknown. In the eastern Pacific near the Baja California Peninsula (BCP), Mexico, tens of thousands of endangered North Pacific loggerhead sea turtles (Caretta caretta) concentrate at a foraging area known to have high rates of fishery bycatch. Because stage survivorship of loggerheads in the BCP will vary significantly depending on the number of years spent in this region, we applied skeletochronology to empirically estimate residency duration in this loggerhead hotspot. The observed age distribution obtained from skeletochronology analysis of 146 dead-stranded loggerheads ranged from three to 24 years old, suggesting a BCP residency of >20 years. Given the maximum estimated age and a one-year migration to western Pacific nesting beaches, we infer age-at-maturation for BCP loggerheads at ~25 years old. We also examine survivorship at varying BCP residency durations by applying our findings to current annual mortality estimates. Predicted survivorship of loggerheads spending over 20 years in this BCP foraging habitat is less than 10%, and given that ~43,000 loggerhead turtles forage here, a significant number of turtles are at extreme risk in this region. This is the first empirical evidence supporting estimated age-at-maturation for BCP North Pacific loggerheads, and the first estimates of BCP stage survivorship. Our findings emphasize the urgent need for continued and effective international conservation efforts to minimize bycatch of this endangered species.
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Affiliation(s)
- Calandra N. Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, CA 92093-0116, USA
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, California 92037, USA
- Corresponding Author: CTT, , 858-334-2842 Address: University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0116
| | - Jeffrey A. Seminoff
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, California 92037, USA
| | - Larisa Avens
- Southeast Fisheries Science Center, NOAA, National Marine Fisheries Service, Beaufort, North Carolina 28516, USA
| | - Lisa R. Goshe
- Southeast Fisheries Science Center, NOAA, National Marine Fisheries Service, Beaufort, North Carolina 28516, USA
| | - S. Hoyt Peckham
- Center for Ocean Solutions, Stanford University, Pacific Grove, California 93940, USA
| | - Juan M. Rguez-Baron
- Marine Biology Department, Universidad Autonoma de Baja California Sur., La Paz, Baja California Sur, Mexico
| | - Kalyn Bickerman
- School of Biology and Ecology, University of Maine, Orono, Maine 04469, USA
| | - Carolyn M. Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, CA 92093-0116, USA
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25
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Sim EL, Booth DT, Limpus CJ. Incubation temperature, morphology and performance in loggerhead (Caretta caretta) turtle hatchlings from Mon Repos, Queensland, Australia. Biol Open 2015; 4:685-92. [PMID: 26002933 PMCID: PMC4467188 DOI: 10.1242/bio.20148995] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Marine turtles are vulnerable to climate change because their life history and reproduction are tied to environmental temperatures. The egg incubation stage is arguably the most vulnerable stage, because marine turtle eggs require a narrow range of temperatures for successful incubation. Additionally, incubation temperature affects sex, emergence success, morphology and locomotor performance of hatchlings. Hatchlings often experience high rates of predation in the first few hours of their life, and increased size or locomotor ability may improve their chances of survival. Between 2010 and 2013 we monitored the temperature of loggerhead (Caretta caretta; Linnaeus 1758) turtle nests at Mon Repos Rookery, and used these data to calculate a mean three day maximum temperature (T3dm) for each nest. We calculated the hatching and emergence success for each nest, then measured the mass, size and locomotor performance of hatchlings that emerged from those nests. Nests with a T3dm greater than 34°C experienced a lower emergence success and produced smaller hatchlings than nests with a T3dm lower than 34°C. Hatchlings from nests with a T3dm below 34°C performed better in crawling and swimming trials than hatchlings from nests with a T3dm above 34°C. Thus even non-lethal increases in global temperatures have the potential to detrimentally affect fitness and survival of marine turtle hatchlings.
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Affiliation(s)
- Elizabeth L Sim
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David T Booth
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Colin J Limpus
- Department of Environment and Heritage Protection, PO Box 2454, Brisbane, QLD 4001, Australia
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Schoeman DS, Schlacher TA, Defeo O. Climate-change impacts on sandy-beach biota: crossing a line in the sand. GLOBAL CHANGE BIOLOGY 2014; 20:2383-92. [PMID: 25121188 DOI: 10.1111/gcb.12505] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Sandy ocean beaches are iconic assets that provide irreplaceable ecosystem services to society. Despite their great socioeconomic importance, beaches as ecosystems are severely under-represented in the literature on climate-change ecology. Here, we redress this imbalance by examining whether beach biota have been observed to respond to recent climate change in ways that are consistent with expectations under climate change. We base our assessments on evidence coming from case studies on beach invertebrates in South America and on sea turtles globally. Surprisingly, we find that observational evidence for climate-change responses in beach biota is more convincing for invertebrates than for highly charismatic turtles. This asymmetry is paradoxical given the better theoretical understanding of the mechanisms by which turtles are likely to respond to changes in climate. Regardless of this disparity, knowledge of the unique attributes of beach systems can complement our detection of climate-change impacts on sandy-shore invertebrates to add rigor to studies of climate-change ecology for sandy beaches. To this end, we combine theory from beach ecology and climate-change ecology to put forward a suite of predictive hypotheses regarding climate impacts on beaches and to suggest ways that these can be tested. Addressing these hypotheses could significantly advance both beach and climate-change ecology, thereby progressing understanding of how future climate change will impact coastal ecosystems more generally.
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27
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Seminoff JA, Eguchi T, Carretta J, Allen CD, Prosperi D, Rangel R, Gilpatrick JW, Forney K, Peckham SH. Loggerhead sea turtle abundance at a foraging hotspot in the eastern Pacific Ocean: implications for at-sea conservation. ENDANGER SPECIES RES 2014. [DOI: 10.3354/esr00601] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Historical versus contemporary climate forcing on the annual nesting variability of loggerhead sea turtles in the Northwest Atlantic Ocean. PLoS One 2013; 8:e81097. [PMID: 24339901 PMCID: PMC3855202 DOI: 10.1371/journal.pone.0081097] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 10/16/2013] [Indexed: 11/19/2022] Open
Abstract
A recent analysis suggested that historical climate forcing on the oceanic habitat of neonate sea turtles explained two-thirds of interannual variability in contemporary loggerhead (Caretta caretta) sea turtle nest counts in Florida, where nearly 90% of all nesting by this species in the Northwest Atlantic Ocean occurs. Here, we show that associations between annual nest counts and climate conditions decades prior to nest counts and those conditions one year prior to nest counts were not significantly different. Examination of annual nest count and climate data revealed that statistical artifacts influenced the reported 31-year lag association with nest counts. The projected importance of age 31 neophytes to annual nest counts between 2020 and 2043 was modeled using observed nest counts between 1989 and 2012. Assuming consistent survival rates among cohorts for a 5% population growth trajectory and that one third of the mature female population nests annually, the 41% decline in annual nest counts observed during 1998–2007 was not projected for 2029–2038. This finding suggests that annual nest count trends are more influenced by remigrants than neophytes. Projections under the 5% population growth scenario also suggest that the Peninsular Recovery Unit could attain the demographic recovery criteria of 106,100 annual nests by 2027 if nest counts in 2019 are at least comparable to 2012. Because the first year of life represents only 4% of the time elapsed through age 31, cumulative survival at sea across decades explains most cohort variability, and thus, remigrant population size. Pursuant to the U.S. Endangered Species Act, staggered implementation of protection measures for all loggerhead life stages has taken place since the 1970s. We suggest that the 1998–2007 nesting decline represented a lagged perturbation response to historical anthropogenic impacts, and that subsequent nest count increases since 2008 reflect a potential recovery response.
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McClure MM, Alexander M, Borggaard D, Boughton D, Crozier L, Griffis R, Jorgensen JC, Lindley ST, Nye J, Rowland MJ, Seney EE, Snover A, Toole C, VAN Houtan K. Incorporating climate science in applications of the US endangered species act for aquatic species. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2013; 27:1222-1233. [PMID: 24299088 DOI: 10.1111/cobi.12166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 05/27/2013] [Indexed: 06/02/2023]
Abstract
Aquatic species are threatened by climate change but have received comparatively less attention than terrestrial species. We gleaned key strategies for scientists and managers seeking to address climate change in aquatic conservation planning from the literature and existing knowledge. We address 3 categories of conservation effort that rely on scientific analysis and have particular application under the U.S. Endangered Species Act (ESA): assessment of overall risk to a species; long-term recovery planning; and evaluation of effects of specific actions or perturbations. Fewer data are available for aquatic species to support these analyses, and climate effects on aquatic systems are poorly characterized. Thus, we recommend scientists conducting analyses supporting ESA decisions develop a conceptual model that links climate, habitat, ecosystem, and species response to changing conditions and use this model to organize analyses and future research. We recommend that current climate conditions are not appropriate for projections used in ESA analyses and that long-term projections of climate-change effects provide temporal context as a species-wide assessment provides spatial context. In these projections, climate change should not be discounted solely because the magnitude of projected change at a particular time is uncertain when directionality of climate change is clear. Identifying likely future habitat at the species scale will indicate key refuges and potential range shifts. However, the risks and benefits associated with errors in modeling future habitat are not equivalent. The ESA offers mechanisms for increasing the overall resilience and resistance of species to climate changes, including establishing recovery goals requiring increased genetic and phenotypic diversity, specifying critical habitat in areas not currently occupied but likely to become important, and using adaptive management. Incorporación de las Ciencias Climáticas en las Aplicaciones del Acta Estadunidense de Especies en Peligro para Especies Acuáticas.
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Affiliation(s)
- Michelle M McClure
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard, East, Seattle, WA, 98112, U.S.A..
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Seney EE, Rowland MJ, Lowery RA, Griffis RB, McClure MM. Climate change, marine environments, and the US Endangered species act. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2013; 27:1138-1146. [PMID: 24299080 DOI: 10.1111/cobi.12167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 04/11/2013] [Indexed: 06/02/2023]
Abstract
Climate change is expected to be a top driver of global biodiversity loss in the 21st century. It poses new challenges to conserving and managing imperiled species, particularly in marine and estuarine ecosystems. The use of climate-related science in statutorily driven species management, such as under the U.S. Endangered Species Act (ESA), is in its early stages. This article provides an overview of ESA processes, with emphasis on the mandate to the National Marine Fisheries Service (NMFS) to manage listed marine, estuarine, and anadromous species. Although the ESA is specific to the United States, its requirements are broadly relevant to conservation planning. Under the ESA, species, subspecies, and "distinct population segments" may be listed as either endangered or threatened, and taking of most listed species (harassing, harming, pursuing, wounding, killing, or capturing) is prohibited unless specifically authorized via a case-by-case permit process. Government agencies, in addition to avoiding take, must ensure that actions they fund, authorize, or conduct are not likely to jeopardize a listed species' continued existence or adversely affect designated critical habitat. Decisions for which climate change is likely to be a key factor include: determining whether a species should be listed under the ESA, designating critical habitat areas, developing species recovery plans, and predicting whether effects of proposed human activities will be compatible with ESA-listed species' survival and recovery. Scientific analyses that underlie these critical conservation decisions include risk assessment, long-term recovery planning, defining environmental baselines, predicting distribution, and defining appropriate temporal and spatial scales. Although specific guidance is still evolving, it is clear that the unprecedented changes in global ecosystems brought about by climate change necessitate new information and approaches to conservation of imperiled species. El Cambio Climático, los Ecosistemas Marinos y el Acta Estadunidense de Especies en Peligro.
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Affiliation(s)
- Erin E Seney
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Science and Technology, 1315 East-West Highway, Silver Spring, MD, 20910, U.S.A.; Erin Seney Consulting, LLC, Woodbridge, VA, 22192, U.S.A
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31
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Nel R, Punt AE, Hughes GR. Are coastal protected areas always effective in achieving population recovery for nesting sea turtles? PLoS One 2013; 8:e63525. [PMID: 23671683 PMCID: PMC3643975 DOI: 10.1371/journal.pone.0063525] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 04/08/2013] [Indexed: 11/21/2022] Open
Abstract
Sea turtles are highly migratory and usually dispersed, but aggregate off beaches during the nesting season, rendering them vulnerable to coastal threats. Consequently, coastal Marine Protection Areas (MPAs) have been used to facilitate the recovery of turtle populations, but the effectiveness of these programs is uncertain as most have been operating for less than a single turtle generation (or<20 yr). South Africa, however, hosts one of the longest running conservation programs, protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles since 1963 in a series of coastal MPAs. This provides a unique opportunity to evaluate the long-term effect of spatial protection on the abundance of two highly migratory turtle species with different life history characteristics. Population responses were assessed by modeling the number of nests over time in an index area (13 km) and an expanded monitoring area (53 km) with varying survey effort. Loggerhead abundance increased dramatically from∼250 to>1700 nests pa (index area) especially over the last decade, while leatherback abundance increased initially∼10 to 70 nests pa (index area), but then stabilized. Although leatherbacks have higher reproductive output per female and comparable remigration periods and hatching success to loggerheads, the leatherback population failed to expand. Our results suggest that coastal MPAs can work but do not guarantee the recovery of sea turtle populations as pressures change over time. Causes considered for the lack of population growth include factors in the MPA (expansion into unmonitored areas or incubation environment) of outside of the MPA (including carrying capacity and fishing mortality). Conservation areas for migratory species thus require careful design to account for species-specific needs, and need to be monitored to keep track of changing pressures.
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Affiliation(s)
- Ronel Nel
- Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa.
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Fuentes MMPB, Pike DA, Dimatteo A, Wallace BP. Resilience of marine turtle regional management units to climate change. GLOBAL CHANGE BIOLOGY 2013; 19:1399-1406. [PMID: 23505145 DOI: 10.1111/gcb.12138] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
Enhancing species resilience to changing environmental conditions is often suggested as a climate change adaptation strategy. To effectively achieve this, it is necessary first to understand the factors that determine species resilience, and their relative importance in shaping the ability of species to adjust to the complexities of environmental change. This is an extremely challenging task because it requires comprehensive information on species traits. We explored the resilience of 58 marine turtle regional management units (RMUs) to climate change, encompassing all seven species of marine turtles worldwide. We used expert opinion from the IUCN-SSC Marine Turtle Specialist Group (n = 33 respondents) to develop a Resilience Index, which considered qualitative characteristics of each RMU (relative population size, rookery vulnerability, and genetic diversity) and non climate-related threats (fisheries, take, coastal development, and pollution/pathogens). Our expert panel perceived rookery vulnerability (the likelihood of functional rookeries becoming extirpated) and non climate-related threats as having the greatest influence on resilience of RMUs to climate change. We identified the world's 13 least resilient marine turtle RMUs to climate change, which are distributed within all three major ocean basins and include six of the world's seven species of marine turtle. Our study provides the first look at inter- and intra-species variation in resilience to climate change and highlights the need to devise metrics that measure resilience directly. We suggest that this approach can be widely used to help prioritize future actions that increase species resilience to climate change.
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Tapilatu RF, Dutton PH, Tiwari M, Wibbels T, Ferdinandus HV, Iwanggin WG, Nugroho BH. Long-term decline of the western Pacific leatherback,Dermochelys coriacea: a globally important sea turtle population. Ecosphere 2013. [DOI: 10.1890/es12-00348.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Jones TT, Bostrom BL, Hastings MD, Van Houtan KS, Pauly D, Jones DR. Resource requirements of the Pacific leatherback turtle population. PLoS One 2012; 7:e45447. [PMID: 23071518 PMCID: PMC3465295 DOI: 10.1371/journal.pone.0045447] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 08/22/2012] [Indexed: 11/23/2022] Open
Abstract
The Pacific population of leatherback sea turtles (Dermochelys coriacea) has drastically declined in the last 25 years. This decline has been linked to incidental capture by fisheries, egg and meat harvesting, and recently, to climate variability and resource limitation. Here we couple growth rates with feeding experiments and food intake functions to estimate daily energy requirements of leatherbacks throughout their development. We then estimate mortality rates from available data, enabling us to raise food intake (energy requirements) of the individual to the population level. We place energy requirements in context of available resources (i.e., gelatinous zooplankton abundance). Estimated consumption rates suggest that a single leatherback will eat upward of 1000 metric tonnes (t) of jellyfish in its lifetime (range 924–1112) with the Pacific population consuming 2.1×106 t of jellyfish annually (range 1.0–3.7×106) equivalent to 4.2×108 megajoules (MJ) (range 2.0–7.4×108). Model estimates suggest 2–7 yr-old juveniles comprise the majority of the Pacific leatherback population biomass and account for most of the jellyfish consumption (1.1×106 t of jellyfish or 2.2×108 MJ per year). Leatherbacks are large gelatinous zooplanktivores with consumption to biomass ratios of 96 (up to 192 if feeding strictly on low energy density Cnidarians); they, therefore, have a large capacity to impact gelatinous zooplankton landscapes. Understanding the leatherback's needs for gelatinous zooplankton, versus the availability of these resources, can help us better assess population trends and the influence of climate induced resource limitations to reproductive output.
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Affiliation(s)
- T Todd Jones
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
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Pajuelo M, Bjorndal KA, Reich KJ, Vander Zanden HB, Hawkes LA, Bolten AB. Assignment of nesting loggerhead turtles to their foraging areas in the Northwest Atlantic using stable isotopes. Ecosphere 2012. [DOI: 10.1890/es12-00220.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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36
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Van Houtan KS, Kittinger JN, Lawrence AL, Yoshinaga C, Born VR, Fox A. Hawksbill Sea Turtles in the Northwestern Hawaiian Islands. CHELONIAN CONSERVATION AND BIOLOGY 2012. [DOI: 10.2744/ccb-0984.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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37
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Heaslip SG, Iverson SJ, Bowen WD, James MC. Jellyfish support high energy intake of leatherback sea turtles (Dermochelys coriacea): video evidence from animal-borne cameras. PLoS One 2012; 7:e33259. [PMID: 22438906 PMCID: PMC3306388 DOI: 10.1371/journal.pone.0033259] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 02/12/2012] [Indexed: 11/18/2022] Open
Abstract
The endangered leatherback turtle is a large, highly migratory marine predator that inexplicably relies upon a diet of low-energy gelatinous zooplankton. The location of these prey may be predictable at large oceanographic scales, given that leatherback turtles perform long distance migrations (1000s of km) from nesting beaches to high latitude foraging grounds. However, little is known about the profitability of this migration and foraging strategy. We used GPS location data and video from animal-borne cameras to examine how prey characteristics (i.e., prey size, prey type, prey encounter rate) correlate with the daytime foraging behavior of leatherbacks (n = 19) in shelf waters off Cape Breton Island, NS, Canada, during August and September. Video was recorded continuously, averaged 1:53 h per turtle (range 0:08–3:38 h), and documented a total of 601 prey captures. Lion's mane jellyfish (Cyanea capillata) was the dominant prey (83–100%), but moon jellyfish (Aurelia aurita) were also consumed. Turtles approached and attacked most jellyfish within the camera's field of view and appeared to consume prey completely. There was no significant relationship between encounter rate and dive duration (p = 0.74, linear mixed-effects models). Handling time increased with prey size regardless of prey species (p = 0.0001). Estimates of energy intake averaged 66,018 kJ•d−1 but were as high as 167,797 kJ•d−1 corresponding to turtles consuming an average of 330 kg wet mass•d−1 (up to 840 kg•d−1) or approximately 261 (up to 664) jellyfish•d-1. Assuming our turtles averaged 455 kg body mass, they consumed an average of 73% of their body mass•d−1 equating to an average energy intake of 3–7 times their daily metabolic requirements, depending on estimates used. This study provides evidence that feeding tactics used by leatherbacks in Atlantic Canadian waters are highly profitable and our results are consistent with estimates of mass gain prior to southward migration.
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Affiliation(s)
- Susan G. Heaslip
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (SGH); (MCJ)
| | - Sara J. Iverson
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W. Don Bowen
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Fisheries and Oceans, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
| | - Michael C. James
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Fisheries and Oceans, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
- * E-mail: (SGH); (MCJ)
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Richards PM, Epperly SP, Heppell SS, King RT, Sasso CR, Moncada F, Nodarse G, Shaver DJ, Medina Y, Zurita J. Sea turtle population estimates incorporating uncertainty: a new approach applied to western North Atlantic loggerheads Caretta caretta. ENDANGER SPECIES RES 2011. [DOI: 10.3354/esr00379] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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