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Serafini G, Gordon CM, Amalfitano J, Wings O, Esteban N, Stokes H, Giusberti L. First evidence of marine turtle gastroliths in a fossil specimen: Paleobiological implications in comparison to modern analogues. PLoS One 2024; 19:e0302889. [PMID: 38709805 PMCID: PMC11073738 DOI: 10.1371/journal.pone.0302889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/15/2024] [Indexed: 05/08/2024] Open
Abstract
Semi-articulated remains of a large chelonioid turtle from the Turonian strata (Upper Cretaceous; ca. 93.9-89.8 Myr) near Sant'Anna d'Alfaedo (Verona province, northeastern Italy) are described for the first time. Together with the skeletal elements, the specimen also preserves pebbles inside the thoracic area which are lithologically distinct from the surrounding matrix. These allochthonous clasts are here interpreted as geo-gastroliths, in-life ingested stones that resided in the digestive tract of the animal. This interpretation marks the first reported evidence of geophagy in a fossil marine turtle. SEM-EDS analysis, together with macroscopic petrological characterization, confirm the presence of both siliceous and carbonatic pebbles. These putative geo-gastroliths have morphometries and size ranges more similar to those of gastroliths in different taxa (fossils and extant) than allochthonous "dropstone" clasts from the same deposit that were carried by floating vegetation A dense pitted pattern of superficial erosion is microscopically recognizable on the carbonatic gastroliths, consistent with surface etching due to gastric acids. The occurrence of a similar pattern was demonstrated by the experimental etching of carbonatic pebbles with synthetic gastric juice. Gut contents of modern green sea turtles (Chelonia mydas) were surveyed for substrate ingestion, providing direct evidence of geophagic behavior in extant chelonioids. Comparison with modern turtle dietary habits may suggests that the pebbles were ingested as a way to supplement calcium after or in preparation for egg deposition, implying that the studied specimen was possibly a gravid female.
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Affiliation(s)
- Giovanni Serafini
- Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Modena, Emilia-Romagna, Italy
| | - Caleb M. Gordon
- Department of Earth & Planetary Sciences, Yale University, New Haven, CT, United States of America
| | - Jacopo Amalfitano
- Centro di Ateneo per i Musei, Università Degli Studi di Padova, Padova, Veneto, Italy
| | - Oliver Wings
- Naturkundemuseum Bamberg, Bamberg, Bavaria, Germany
- Staatliche Naturwissenschaftliche Sammlungen Bayerns, München, Germany
| | - Nicole Esteban
- Faculty of Science and Engineering, Swansea University, Swansea, Wales, United Kingdom
| | - Holly Stokes
- Faculty of Science and Engineering, Swansea University, Swansea, Wales, United Kingdom
| | - Luca Giusberti
- Dipartimento di Geoscienze, Università Degli Studi di Padova, Padova, Veneto, Italy
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Hays GC, Laloë JO, Mortimer JA, Rattray A, Tromp JJ, Esteban N. Remote submerged banks and mesophotic ecosystems can provide key habitat for endangered marine megafauna. SCIENCE ADVANCES 2024; 10:eadl2838. [PMID: 38381823 PMCID: PMC10881038 DOI: 10.1126/sciadv.adl2838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/18/2024] [Indexed: 02/23/2024]
Abstract
The importance of some ecosystems remains poorly understood. We showed that mesophotic ecosystems (30 to 150 m) are a key habitat for a critically endangered species, with strong evidence that a globally important population of adult hawksbill turtles (Eretmochelys imbricata) almost exclusively foraged at these depths on remote submerged banks. This discovery highlights the need for such areas to be included in conservation planning, for example, as part of the United Nations High Seas Treaty. We equipped nesting turtles with Fastloc-GPS (Global Positioning System) satellite tags at an Indian Ocean breeding area and they all traveled to deep foraging sites (6765 days of tracking data across 22 individuals including 183,921 dive-depth measurements) rather than shallow coral reef sites. Both chart depths and depth data relayed from the tags indicated that turtles foraged at mesophotic depths, the modal dive depths being between 35 and 40 m. We calculate that 55,554 km2 of the western Indian Ocean alone consists of submerged banks between 30 and 60 m.
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Affiliation(s)
- Graeme C. Hays
- Deakin Marine Research and Innovation Centre, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia
| | - Jacques-Olivier Laloë
- Deakin Marine Research and Innovation Centre, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia
| | - Jeanne A. Mortimer
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- PO Box 1443, Victoria, Mahé, Seychelles
| | - Alex Rattray
- Deakin Marine Research and Innovation Centre, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia
| | - Jared J. Tromp
- Deakin Marine Research and Innovation Centre, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia
| | - Nicole Esteban
- Department of Biosciences, Swansea University, Swansea SA2 8PP, Wales, UK
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Laloë JO, Hays GC. Can a present-day thermal niche be preserved in a warming climate by a shift in phenology? A case study with sea turtles. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221002. [PMID: 36778962 PMCID: PMC9905989 DOI: 10.1098/rsos.221002] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
How species respond to climate change may impact their extinction probability. Here we link climatology and ecology to tackle a globally important conservation question. For sea turtles, there are concerns that climate warming will cause both the feminization of populations as well as reduced hatchling survival. For 58 nesting sites across the world spanning all seven sea turtle species, we investigated whether warming might be avoided by shifts in nesting phenology to a cooler part of the year. We show that even with the most extreme phenological shift that has been reported to date-an 18-day advance in nesting per °C increase in sea surface temperature (SST)-temperatures will continue to increase at nesting sites with climate warming. We estimate that SST at nesting sites will rise by an average of 0.6°C (standard deviation = 0.9°C, n = 58) when we model a 1.5°C rise in SST combined with a best-case-scenario shift in nesting. Since sea turtles exhibit temperature-dependent sex determination, these temperature rises could lead to increasingly female-biased sex ratios as well as reduced hatchling production at sites across the world. These findings underscore concerns for the long-term survival of this iconic group.
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Salvarani PI, Vieira LR, Rendón-von Osten J, Morgado F. Hawksbill Sea Turtle ( Eretmochelys imbricata) Blood and Eggs Organochlorine Pesticides Concentrations and Embryonic Development in a Nesting Area (Yucatan Peninsula, Mexico). TOXICS 2023; 11:50. [PMID: 36668776 PMCID: PMC9865186 DOI: 10.3390/toxics11010050] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/21/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
Environmental contaminants with chemical origins, such as organochlorine pesticides (OCPs) have major impacts on the health of marine animals, including sea turtles, due to the bioaccumulation of those substances by transference throughout the food chain. The effects of environmental pollution on the health of marine turtles are very important for management strategies and conservation. During recent decades, the south Gulf of Mexico and the Yucatan Peninsula have suffered from increasingly frequent disturbances from continental landmasses, river systems, urban wastewater runoff, port areas, tourism, industrial activities, pesticides from agricultural use, and other pollutants, such as metals, persistent organic pollutants (POPs) and hydrocarbons (from the oil industry activities), which contaminate water and sediments and worsen the environmental quality of the marine ecosystem in this region. In this study, we assessed the concentrations of OCPs in the blood and eggs of 60 hawksbill turtles (Eretmochelys imbricata) nesting at the Punta Xen turtle camp, and their effects on the nesting population's reproductive performance: specifically, maternal transfer and embryonic development were analyzed. Hematologic characteristics, including packed cell volume, white blood cell count, red blood cell count, and haemoglobin levels, and plasma chemistry values, including creatinine, blood urea nitrogen, uric acid, triglyceride, total cholesterol and glucose, were also measured. The general health of the turtles in this study, as well as their levels of urea, serum creatinine, glucose, uric, acid, cholesterol, and triglyceride, fell within normal ranges and was similar to other normal values, which could indicate the turtles' good energy levels and body conditions for nest-building activity, with all of the turtles able to successfully come ashore to nest. All the same, the obtained results also indicate that OCPs affect the nesting and reproductive performance of the hawksbill turtles, as well as their fertility and the development of the population of eggs and reproductive performance, specifically in terms of maternal transference and embryonic development. There were significant differences in the concentrations of OCPs (ΣHCHs and ΣDienes) between maternal blood and eggs, indicating that these chemicals are transferred from nesting females to eggs and, ultimately, to hatchlings. OCPs may, therefore, have an effect on the health and reproductive performance of hawksbill turtles, both in terms of their fertility and egg development. Conservation strategies need to be species-specific, due to differences in feeding, and address the reasons for any decline, focusing on regional assessments. Thus, accurate and comparable monitoring data are necessary, which requires the standardization of monitoring protocols.
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Affiliation(s)
- Patricia I. Salvarani
- Department of Biology and the Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, Portugal
| | - Luis R. Vieira
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 2250-208 Matosinhos, Portugal
- School of Medicine and Biomedical Sciences (ICBAS), University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Jaime Rendón-von Osten
- Instituto Epomex, Universidad Autónoma de Campeche, Av Augustin de Melgar y Juan de la Barrera s/n, Campeche 24039, Mexico
| | - Fernando Morgado
- Department of Biology and the Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, Portugal
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Cassill DL, Watkins A. Nest-site choice by loggerhead sea turtles as a risk-management adaptation to offset hatching failure by unpredictable storms and predators. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.850091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
IntroductionAlong the coasts of Florida, United States, the nesting season of the loggerhead sea turtle, Caretta caretta, overlaps with the hurricane season. Nesting loggerhead females do not extend parental protection beyond depositing eggs in sandy, excavated nests in locations that provide a viable range of temperatures, moisture, and respiratory gas exchange. Thereafter, a female’s clutches are subjected to the uncertainties of desiccation, predation, flooding, or beach erosion.MethodsHere, we used data from a 1996-2004 study of 94 tagged loggerhead females nesting on a small barrier island off the Gulf Coast of south Florida, United States. We tested the hypothesis that the distribution of nest sites by loggerhead females was a randomized response to unpredictable hatching failure.ResultsWe show that nest site choice accounted for 19.2% of variation in hatching success whereas breeding year and breeding month accounted for the remaining 81.8% of variation in hatching success. We show that the emergence site along the beach-length axis, nest site choice along the beach-width axis, and distances between nest locations did not fit a uniform-random distribution or a normal distribution. Instead, we show that loggerhead females employed a “Goldilocks” distribution in which nest sites were “neither too clustered nor too dispersed.” Moreover, loggerhead females selected nest sites with limited overlap with nest sites from previous breeding seasons.DiscussionWe propose that nest site choice by this population of loggerhead females constitutes a significant maternal risk-management adaptation that deserves thoughtful consideration as we continue to assess the impacts of climate change on the future of loggerhead sea turtles.
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Lowe CD, Tregenza NJC, Allen CJ, Blow GE, Nuuttila H, Bertelli CM, Mendzil AF, Stamp T, Sheehan EV, Davies P, Gordon JCD, Bolland JD, Britton JR, Main R, Velterop R, Crundwell C, Schofield A, Clarke DRK. A novel method for identifying coded tags recorded on aquatic acoustic monitoring systems. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 194:806. [PMID: 36123542 PMCID: PMC9485084 DOI: 10.1007/s10661-022-10500-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 09/10/2022] [Indexed: 06/15/2023]
Abstract
Aquatic biotelemetry increasingly relies on using acoustic transmitters ('tags') that enable passive detection of tagged animals using fixed or mobile receivers. Both tracking methods are resource-limited, restricting the spatial area in which movements of highly mobile animals can be measured using proprietary detection systems. Transmissions from tags are recorded by underwater noise monitoring systems designed for other purposes, such as cetacean monitoring devices, which have been widely deployed in the marine environment; however, no tools currently exist to decode these detections, and thus valuable additional information on animal movements may be missed. Here, we describe simple hybrid methods, with potentially wide application, for obtaining information from otherwise unused data sources. The methods were developed using data from moored, acoustic cetacean detectors (C-PODs) and towed passive receiver arrays, often deployed to monitor the vocalisations of cetaceans, but any similarly formatted data source could be used. The method was applied to decode tag detections that were found to have come from two highly mobile fish species, bass (Dicentrarchus labrax) and Twaite shad (Alosa fallax), that had been tagged in other studies. Decoding results were validated using test tags; range testing data were used to demonstrate the relative efficiency of these receiver methods in detecting tags. This approach broadens the range of equipment from which acoustic tag detections can be decoded. Novel detections derived from the method could add significant value to past and present tracking studies at little additional cost, by providing new insights into the movement of mobile animals at sea.
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Affiliation(s)
| | | | - Claudia J Allen
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - Georgina E Blow
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - Hanna Nuuttila
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - Chiara M Bertelli
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - Anouska F Mendzil
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - Thomas Stamp
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Emma V Sheehan
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Peter Davies
- Department of Life and Environmental Sciences, Bournemouth University, Poole, BH12 5BB, UK
- Hull International Fisheries Institute, University of Hull, Hull, HU6 7RX, UK
| | - Jonathan C D Gordon
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
- Vanishing Point Marine, 8 Admiral's Hard, Stonehouse, Plymouth, PL1 3RJ, UK
| | - Jonathan D Bolland
- Hull International Fisheries Institute, University of Hull, Hull, HU6 7RX, UK
| | - J Robert Britton
- Department of Life and Environmental Sciences, Bournemouth University, Poole, BH12 5BB, UK
| | - Robert Main
- Marine Scotland Science, 375 Victoria Road, Aberdeen, AB11 9DB, UK
| | | | - Charles Crundwell
- Environment Agency, Riversmeet House, Northway Lane, Tewkesbury, Gloucestershire, GL20 8JG, UK
| | - Andrew Schofield
- Salar Environmental Services Ltd, Merthyr Mawr Rd, Bridgend, CF31 3NR, UK
| | - David R K Clarke
- SEACAMS, College of Science, Swansea University, Swansea, SA2 8PP, UK
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Mayne B, Mustin W, Baboolal V, Casella F, Ballorain K, Barret M, Vanderklift MA, Tucker AD, Korbie D, Jarman S, Berry O. Age prediction of green turtles with an epigenetic clock. Mol Ecol Resour 2022; 22:2275-2284. [DOI: 10.1111/1755-0998.13621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/29/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Benjamin Mayne
- Environomics Future Science Platform Indian Oceans Marine Research Centre Commonwealth Scientific and Industrial Research Organisation (CSIRO) Crawley Western Australia Australia
| | - Walter Mustin
- Cayman Turtle Conservation and Education Centre Grand Cayman KY1‐1301 Cayman Islands
| | - Vandanaa Baboolal
- Cayman Turtle Conservation and Education Centre Grand Cayman KY1‐1301 Cayman Islands
| | - Francesca Casella
- Cayman Turtle Conservation and Education Centre Grand Cayman KY1‐1301 Cayman Islands
| | - Katia Ballorain
- Centre d'Etude et de Découverte des Tortues Marines (CEDTM) 19 Cité des Frangipaniers 97424 Piton Saint‐Leu, La Réunion France
| | - Mathieu Barret
- Kélonia l’observatoire des tortues marines 46 Rue Général de Gaulle 97436 Saint‐Leu, La Réunion France
| | - Mathew A. Vanderklift
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Oceans and Atmosphere Crawley Western Australia Australia
| | - Anton D. Tucker
- Department of Biodiversity, Conservation and Attractions Marine Science Program Kensington Western Australia Australia
| | - Darren Korbie
- Australian Institute for Bioengineering and Nanotechnology The University of Queensland Brisbane Queensland Australia
| | - Simon Jarman
- School of Biological Sciences University of Western Australia 35 Stirling Highway Perth Western Australia Australia
| | - Oliver Berry
- Environomics Future Science Platform Indian Oceans Marine Research Centre Commonwealth Scientific and Industrial Research Organisation (CSIRO) Crawley Western Australia Australia
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Hamann M, Shimada T, Duce S, Foster A, To ATY, Limpus C. Patterns of nesting behaviour and nesting success for green turtles at Raine Island, Australia. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To understand how turtles use the nesting habitat at Raine Island across a nesting season, and how the turtles respond to the restoration of the island’s dune systems, we identified 534 nesting events for 39 green turtles Chelonia mydas across 2 breeding seasons using data derived from satellite tags. Tracked turtles laid between 4 and 10 clutches of eggs. Patterns of nesting success varied between individuals, within and between seasons. Nesting success was higher in 2018-19 (57%) than 2017-18 (45%), and in both years, nesting success was lowest between October and early January (<50%). In 2017-18, increased rainfall in January corresponded with increased nesting success (>50%). The density of female turtles ashore was lower in 2018-19, and likely explains higher nesting success in 2018-19 because competition for nest space was lower. In 2017-18, females had more attempts per clutch, and the attempts were around 90 min longer. Consequently, energy required to lay a clutch of eggs in 2017-18 was significantly higher than in 2018-19, highlighting potential costs of lower nesting success rates on reproductive output. The area of beach re-profiled as an intervention in 2014 and 2017 was a nesting hotspot in 2017-18. However, in 2018-19, the area was not used to the same extent, and the nesting hotspot occurred on the north-eastern unaltered beach. Collectively, the tracking of turtles across the whole nesting season enabled us to assess overall beach use and nesting site fidelity of green turtles at Raine Island. Results will aid future planning and management of beach restoration activities at turtle nesting sites.
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Affiliation(s)
- M Hamann
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
| | - T Shimada
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
- Queensland Department of Environment and Science, Brisbane, Qld 4102, Australia
| | - S Duce
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
| | - A Foster
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
| | - ATY To
- College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia
| | - C Limpus
- Queensland Department of Environment and Science, Brisbane, Qld 4102, Australia
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Pritchard AM, Sanchez CL, Bunbury N, Burt AJ, Currie JC, Doak N, Fleischer-Dogley F, Metcalfe K, Mortimer JA, Richards H, van de Crommenacker J, Godley BJ. Green turtle population recovery at Aldabra Atoll continues after 50 yr of protection. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Green turtles Chelonia mydas have been subject to high levels of anthropogenic exploitation, with harvesting at their nesting sites especially pronounced throughout the late 19th and early 20th centuries, leading to worldwide declines. Due to their delayed sexual maturity, long-term protection and monitoring is crucial to allow and accurately demonstrate population recovery. Subsequent to their exploitation, Aldabra Atoll (Republic of Seychelles) has offered the longest continuous protection for nesting green turtles anywhere in the Western Indian Ocean, beginning in 1968. Here, we document the continuing recovery of that population by estimating clutch production within 12 mo nesting seasons over 50 yr of monitoring. An estimated mean of 15297 clutches were laid annually between December 2014 and November 2019. This represents an increase of 173% since Aldabra’s intensive monitoring programme was initiated in 1980, and 410-�665% since 1968. Clutch number increases were recorded at all but 1 of 6 monitored beach groups around the atoll but were most pronounced at Settlement Beach, where exploitation of nesting females was historically most intense. Seasonality data since 2000 showed a year-round nesting season, with elevated activity in April-June peaking on average in May, and a potential shift to later in the year over time. This study highlights the considerable contribution of Aldabra Atoll to regional green turtle numbers and the benefit of long-term protection and monitoring at what can be considered a global reference site for this species.
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Affiliation(s)
- AM Pritchard
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall TR10 9FE, UK
| | - CL Sanchez
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
- Department of Biology, University of Pisa, Via A. Volta 6, 56126 Pisa, Italy
| | - N Bunbury
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall TR10 9FE, UK
| | - AJ Burt
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
- Department of Plant Sciences, Oxford University, South Parks Road, OX1 3RB, UK
| | - JC Currie
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
- South African National Biodiversity Institute, Kirstenbosch Botanical Gardens, Claremont, Cape Town, Western Cape 7735, South Africa
- Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, 6031, South Africa
| | - N Doak
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
| | - F Fleischer-Dogley
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
| | - K Metcalfe
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall TR10 9FE, UK
| | - JA Mortimer
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA
| | - H Richards
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
| | - J van de Crommenacker
- Seychelles Islands Foundation, La Ciotat Building, Mont Fleuri, Victoria, PO Box 853, Seychelles
| | - BJ Godley
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall TR10 9FE, UK
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Jeantet L, Hadetskyi V, Vigon V, Korysko F, Paranthoen N, Chevallier D. Estimation of the Maternal Investment of Sea Turtles by Automatic Identification of Nesting Behavior and Number of Eggs Laid from a Tri-Axial Accelerometer. Animals (Basel) 2022; 12:ani12040520. [PMID: 35203228 PMCID: PMC8868198 DOI: 10.3390/ani12040520] [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: 01/19/2022] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary During the reproduction period, female sea turtles come several times onto the beaches to lay their eggs. Monitoring of the nesting populations is therefore important to estimate the state of a population and its future. However, measuring the clutch size and frequency of sea turtles is tedious work that requires rigorous monitoring of the nesting site throughout the breeding season. In order to support the fieldwork, we propose an automatic method to remotely record the behavior on land of the sea turtles from animal-attached sensors; an accelerometer. The proposed method estimates, with an accuracy of 95%, the behaviors on land of sea turtles and the number of eggs laid. This automatic method should therefore help researchers monitor nesting sea turtle populations and contribute to improving global knowledge on the demographic status of these threatened species. Abstract Monitoring reproductive outputs of sea turtles is difficult, as it requires a large number of observers patrolling extended beaches every night throughout the breeding season with the risk of missing nesting individuals. We introduce the first automatic method to remotely record the reproductive outputs of green turtles (Chelonia mydas) using accelerometers. First, we trained a fully convolutional neural network, the V-net, to automatically identify the six behaviors shown during nesting. With an accuracy of 0.95, the V-net succeeded in detecting the Egg laying process with a precision of 0.97. Then, we estimated the number of laid eggs from the predicted Egg laying sequence and obtained the outputs with a mean relative error of 7% compared to the observed numbers in the field. Based on deployment of non-invasive and miniature loggers, the proposed method should help researchers monitor nesting sea turtle populations. Furthermore, its use can be coupled with the deployment of accelerometers at sea during the intra-nesting period, from which behaviors can also be estimated. The knowledge of the behavior of sea turtle on land and at sea during the entire reproduction period is essential to improve our knowledge of this threatened species.
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Affiliation(s)
- Lorène Jeantet
- Institut Pluridisciplinaire Hubert Curien, CNRS–Unistra, 67087 Strasbourg, France;
- Correspondence:
| | - Vadym Hadetskyi
- UFR Math-Info, Université de Strasbourg, 7 rue Descartes, CEDEX, 67081 Strasbourg, France; (V.H.); (V.V.)
| | - Vincent Vigon
- UFR Math-Info, Université de Strasbourg, 7 rue Descartes, CEDEX, 67081 Strasbourg, France; (V.H.); (V.V.)
| | - François Korysko
- Office Français de la Biodiversité, Direction des Outre-mer, Délégation Guyane, 44 rue Pasteur, BP 10808, 97338 Cayenne, France; (F.K.); (N.P.)
| | - Nicolas Paranthoen
- Office Français de la Biodiversité, Direction des Outre-mer, Délégation Guyane, 44 rue Pasteur, BP 10808, 97338 Cayenne, France; (F.K.); (N.P.)
| | - Damien Chevallier
- Institut Pluridisciplinaire Hubert Curien, CNRS–Unistra, 67087 Strasbourg, France;
- BOREA Research Unit, National Museum of Natural History (MNHN), UMR CNRS 7208, Sorbonne Université, French Institute for Research and Development (IRD 207), University of Caen Normandie, University of Antilles, CEDEX 05, 75231 Paris, France
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van de Geer CH, Bourjea J, Broderick AC, Dalleau M, Fernandes RS, Harris LR, Inteca GE, Kiponda FK, Louro CMM, Mortimer JA, Msangameno D, Mwasi LD, Nel R, Okemwa GM, Olendo M, Pereira MAM, Rees AF, Silva I, Singh S, West L, Williams JL, Godley BJ. Marine turtles of the African east coast: current knowledge and priorities for conservation and research. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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12
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Abstract
AbstractOne of the largest nesting colonies of the Vulnerable loggerhead sea turtle Caretta caretta is in Cabo Verde. Here we present the first comprehensive study of loggerhead turtle nesting on the island of Maio in Cabo Verde. During 2016–2019 we monitored 38 km of undeveloped sandy beaches that have minimal artificial lighting and where all nesting on Maio takes place. We counted 4,063 nests in 2016, 5,429 in 2017, 14,364 in 2018 and 7,937 in 2019. The estimated total number of females was 1,016, 1,357, 3,591 and 1,984 in each of these years, respectively. Our findings suggest there are more loggerhead turtles nesting in Cabo Verde than previously estimated, and that this could be the species’ largest nesting subpopulation (followed by Florida, USA and Oman). The inter-annual hatching success (the proportion of eggs producing hatchlings) was 29–38% for the whole island but varied between sites. Our study of 250 clutches showed that flooding affected 38–61% and predation by crabs 40–42%, with hatching success on different beaches in the range of 1–59%. Poaching of eggs was rare (< 2% of clutches), but dogs predated 68.4% of all clutches on the beach nearest the largest human settlement. We evaluated different nest management strategies at multiple sites and estimated productivity of hatchlings (the number of hatchlings that would reach the sea for each management strategy), finding that hatcheries are not always the best option for nest management. As the beaches on Maio are relatively undisturbed, and there is a high abundance and density of turtle nests, the island should be protected as a globally important site for the conservation of the loggerhead turtle, and of coastal biodiversity more broadly.
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13
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Hays GC, Mortimer JA, Rattray A, Shimada T, Esteban N. High accuracy tracking reveals how small conservation areas can protect marine megafauna. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02418. [PMID: 34278636 DOI: 10.1002/eap.2418] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/01/2021] [Accepted: 03/03/2021] [Indexed: 06/13/2023]
Abstract
Space use estimates can inform conservation management but relaying high-accuracy locations is often not straightforward. We used Fastloc-GPS Argos satellite tags with the innovation of additional data relay via a ground station (termed a "Mote") to record high volumes (typically >20 locations per individual per day) of high accuracy tracking data. Tags were attached in the Chagos Archipelago (Indian Ocean) in 2018-2019 to 23 immature turtles of two species for which there have been long-standing conservation concerns: 21 hawksbill turtles (Eretmochelys imbricata) and two green turtles (Chelonia mydas). Over long tracking durations (mean 227.6 d per individual), most turtles moved very little. For example, 17 of 21 hawksbill turtles remained continuously in the lagoon where they were equipped, with 95% and 50% utilization distributions (UDs) averaging only 1.03 and 0.18 km2 , respectively. Many individuals, and both species, could use the same small spaces, i.e., individuals did not maintain unique home ranges. However, three hawksbill turtles travelled hundreds of kilometers from the tagging site. Our results show that, for some large marine vertebrates, even small protected areas of only a few square kilometers can encompass the movements of a large proportion of individuals over long periods. High accuracy tracking may likewise reveal the details of space use for many other animals that move little and/or use important focal areas and where previous low-accuracy tracking techniques have tended to overestimate space use.
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Affiliation(s)
| | - Jeanne A Mortimer
- Department of Biology, University of Florida, Gainesville, Florida, 32611, USA
- P.O. Box 1443, Victoria, Mahé, Seychelles
| | | | - Takahiro Shimada
- Department of Environment and Science, Queensland Government, GPO Box 2454, Dutton Park, Brisbane, Queensland, 4001, Australia
| | - Nicole Esteban
- Department of Biosciences, Swansea University, Swansea, Wales, SA2 8PP, United Kingdom
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14
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Schofield G, Dickson LCD, Westover L, Dujon AM, Katselidis KA. COVID-19 disruption reveals mass-tourism pressure on nearshore sea turtle distributions and access to optimal breeding habitat. Evol Appl 2021; 14:2516-2526. [PMID: 34548882 PMCID: PMC8444759 DOI: 10.1111/eva.13277] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/30/2022] Open
Abstract
Quantifying the extent to which animals detect and respond to human presence allows us to identify pressure (disturbance) and inform conservation management objectively; however, obtaining baselines against which to compare human impact is hindered in areas where human activities are already well established. For example, Zakynthos Island (Greece, Mediterranean) receives around 850,000 visitors each summer, while supporting an important loggerhead sea turtle rookery (~300 individuals/season). The coronavirus (COVID-19)-driven absence of tourism in May-June 2020 provided an opportunity to evaluate the distribution dynamics of this population in the absence (2020) vs. presence (2018 and 2019) of visitors using programmed unmanned aerial system (UAS) surveys. Ambient sea temperature transitioned from suboptimal for breeding in May to optimal in late June, with turtle distribution appearing to shift from shallow (to benefit from waters 3-5°C above ambient) to deeper waters in 2018 and 2019, but not 2020. The 2020 data set demonstrated that increased tourism pressure, not temperature, drives turtles offshore. Specifically, >50% of turtles remained within 100 m of shore at densities of 25-50 visitors/km, even when sea temperature rose, with 2018 and 2019 data supporting this trend. Reduced access to warmer, nearshore waters by tourism could delay the onset of nesting and increase the length of the egg maturation period between nesting events (internesting interval) at this site. A coastal refuge zone could be delimited in May-June where touristic infrastructure is minimal, but also where turtles frequently aggregate. In conclusion, sea turtles appear capable of perceiving changes in the level of human pressure at fine spatial and temporal scales and adjusting their distribution accordingly.
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Affiliation(s)
- Gail Schofield
- School of Biological and Chemical Sciences Queen Mary University of London London UK
| | - Liam C D Dickson
- School of Biological and Chemical Sciences Queen Mary University of London London UK
| | - Lucy Westover
- School of Biological Sciences University of Bristol Bristol UK
| | - Antoine M Dujon
- Centre for Integrative Ecology School of Life and Environmental Sciences Deakin University Geelong Vic. Australia
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15
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Hays GC, Laloë J, Rattray A, Esteban N. Why do Argos satellite tags stop relaying data? Ecol Evol 2021; 11:7093-7101. [PMID: 34141278 PMCID: PMC8207149 DOI: 10.1002/ece3.7558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/17/2021] [Accepted: 03/22/2021] [Indexed: 11/18/2022] Open
Abstract
Satellite tracking of animals is very widespread across a range of marine, freshwater, and terrestrial taxa. Despite the high cost of tags and the advantages of long deployments, the reasons why tracking data from tags stop being received are rarely considered, but possibilities include shedding of the tag, damage to the tag (e.g., the aerial), biofouling, battery exhaustion, or animal mortality.We show how information relayed via satellite tags can be used to assess why tracking data stop being received. As a case study to illustrate general approaches that are broadly applicable across taxa, we examined data from Fastloc-GPS Argos tags deployed between 2012 and 2019 on 78 sea turtles of two species, the green turtle (Chelonia mydas) and the hawksbill turtle (Eretmochelys imbricata).Tags transmitted for a mean of 267 days (SD = 113 days, range: 26-687 days, median = 251 days). In 68 of 78 (87%) cases, battery failure was implicated as the reason why tracking data stopped being received. Some biofouling of the saltwater switches, which synchronize transmissions with surfacing, was evident in a few tags but never appeared to be the reason that data reception ceased.Objectively assessing why tags fail will direct improvements to tag design, setup, and deployment regardless of the study taxa. Assessing why satellite tags stop transmitting will also inform on the fate of tagged animals, for example, whether they are alive or dead at the end of the study, which may allow improved estimates of survival rates.
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Affiliation(s)
- Graeme C. Hays
- School of Life and Environmental SciencesDeakin UniversityGeelongVic.Australia
| | | | - Alex Rattray
- School of Life and Environmental SciencesDeakin UniversityGeelongVic.Australia
| | - Nicole Esteban
- Faculty of Science and EngineeringSwansea UniversitySwanseaUK
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16
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Omeyer LCM, Stokes KL, Beton D, Çiçek BA, Davey S, Fuller WJ, Godley BJ, Sherley RB, Snape RTE, Broderick AC. Investigating differences in population recovery rates of two sympatrically nesting sea turtle species. Anim Conserv 2021. [DOI: 10.1111/acv.12689] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- L. C. M. Omeyer
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
| | - K. L. Stokes
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
- Department of Biosciences Swansea University Singleton Park Swansea UK
| | - D. Beton
- Society for the Protection of Turtles Gönyeli North Cyprus
| | - B. A. Çiçek
- Faculty of Arts and Sciences Eastern Mediterranean University Famagusta North Cyprus
| | - S. Davey
- Society for the Protection of Turtles Gönyeli North Cyprus
| | - W. J. Fuller
- Society for the Protection of Turtles Gönyeli North Cyprus
- Faculty of Veterinary Medicine Near East University Nicosia North Cyprus
| | - B. J. Godley
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
| | - R. B. Sherley
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
| | - R. T. E. Snape
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
- Society for the Protection of Turtles Gönyeli North Cyprus
| | - A. C. Broderick
- Centre for Ecology and Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
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17
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Harrison CS, Luo JY, Putman NF, Li Q, Sheevam P, Krumhardt K, Stevens J, Long MC. Identifying global favourable habitat for early juvenile loggerhead sea turtles. J R Soc Interface 2021; 18:20200799. [PMID: 33622144 DOI: 10.1098/rsif.2020.0799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Loggerhead sea turtles (Caretta caretta) nest globally on sandy beaches, with hatchlings dispersing into the open ocean. Where these juveniles go and what habitat they rely on remains a critical research question for informing conservation priorities. Here a high-resolution Earth system model is used to determine the biophysical geography of favourable ocean habitat for loggerhead sea turtles globally during their first year of life on the basis of ocean current transport, thermal constraints and food availability (defined here as the summed lower trophic level carbon biomass). Dispersal is simulated from eight major nesting sites distributed across the globe in four representative years using particle tracking. Dispersal densities are identified for all turtles, and for the top 15% 'best-fed' turtles that have not encountered metabolically unfavourable temperatures. We find that, globally, rookeries are positioned to disperse to regions where the lower trophic biomass is greatest within loggerheads' thermal range. Six out of the eight nesting sites are associated with strong coastal boundary currents that rapidly transport hatchlings to subtropical-subpolar gyre boundaries; narrow spatial migratory corridors exist for 'best-fed' turtles associated with these sites. Two other rookeries are located in exceptionally high-biomass tropical regions fuelled by natural iron fertilization. 'Best-fed' turtles tend to be associated with lower temperatures, highlighting the inverse relationship between temperature and lower trophic biomass. The annual mean isotherms between 20°C and the thermal tolerance of juvenile loggerheads are a rough proxy for favourable habitat for loggerheads from rookeries associated with boundary currents. Our results can be used to constrain regions for conservation efforts for each subpopulation, and better identify foraging habitat for this critical early life stage.
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Affiliation(s)
- Cheryl S Harrison
- National Center for Atmospheric Research, Boulder, CO 80305, USA.,Institute of Alpine and Arctic Research, University of Colorado, Boulder, CO 80303, USA.,School of Earth Environmental and Marine Science, University of Texas, Rio Grande Valley, Port Isabel, TX 78578, USA
| | - Jessica Y Luo
- National Center for Atmospheric Research, Boulder, CO 80305, USA.,NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA
| | | | | | - Pooja Sheevam
- Institute of Alpine and Arctic Research, University of Colorado, Boulder, CO 80303, USA.,Department of Geological Sciences and Engineering, University of Nevada, Reno, NV 89557, USA
| | - Kristen Krumhardt
- National Center for Atmospheric Research, Boulder, CO 80305, USA.,Institute of Alpine and Arctic Research, University of Colorado, Boulder, CO 80303, USA
| | - Jessica Stevens
- School of Earth Environmental and Marine Science, University of Texas, Rio Grande Valley, Port Isabel, TX 78578, USA
| | - Matthew C Long
- National Center for Atmospheric Research, Boulder, CO 80305, USA
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18
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Barr CE, Hamann M, Shimada T, Bell I, Limpus CJ, Ferguson J. Post-nesting movements and feeding ground distribution by the hawksbill turtle (Eretmochelys imbricata) from rookeries in the Torres Strait. WILDLIFE RESEARCH 2021. [DOI: 10.1071/wr20183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ContextHawksbill sea turtles (Eretmochelys imbricata) are conservation-dependent species in many areas of the world. A key component to ensuring successful conservation initiatives for the species is understanding their distribution and habitat use, in particular, knowing the nesting sites, migration routes and foraging areas for each genetic stock, and how these might overlap with threats.
AimsInvestigate the post-nesting movements of hawksbill sea turtles nesting in the Torres Strait, including migration movements and foraging ground size and distribution.
MethodsNine nesting hawksbill turtles of the north-eastern Australian genetic stock were satellite-tagged between the 2010 and 2019 nesting seasons for 182 ± 143 days (mean ± s.d.).
Key resultsThree turtles continued to nest on adjacent islands before commencing their post-nesting migrations. From the nine tracked turtles, the following three migration movement strategies were identified: (1) direct migration between the nesting beach and foraging ground, (2) non-direct movements with a period of meandering, and (3) establishment of two foraging areas separated by direct movement pathways. Foraging grounds were distributed across the Torres Strait and north-eastern Australia and varied in size between 0.54 km2 and 3.31 km2 (95% UD). None of the turtles migrated outside of Australian waters.
ConclusionsThe localisation of these movements and habitats within Australian waters provides a unique conservation opportunity, whereby protection efforts involve multiple life stages and potentially preserve turtles from multiple genetic stocks. The variety of inter-nesting, migration and home range strategies used by the tracked turtles in the present study highlight the broad scope of hawksbill movements.
ImplicationsOur findings are useful for the implementation of future marine conservation areas and shed light into the nesting, migratory and foraging behaviours of hawkbills from this genetic stock. An understanding of the movement tracks and habitats used by a genetic pool is essential for well grounded implementation of conservation areas and management regulations.
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19
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Hatase H, Omuta K. Trophically polymorphic loggerhead sea turtles show similar interannual variability in clutch frequencies: implications for estimating population size of iteroparous animals. J Zool (1987) 2020. [DOI: 10.1111/jzo.12830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- H. Hatase
- Atmosphere and Ocean Research Institute The University of Tokyo Kashiwa Chiba Japan
| | - K. Omuta
- Yakushima Sea Turtle Research Group Yakushima Kagoshima Japan
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20
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Hays GC, Rattray A, Esteban N. Addressing tagging location bias to assess space use by marine animals. J Appl Ecol 2020. [DOI: 10.1111/1365-2664.13720] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Putman NF, Hawkins J, Gallaway BJ. Managing fisheries in a world with more sea turtles. Proc Biol Sci 2020; 287:20200220. [PMID: 32605516 DOI: 10.1098/rspb.2020.0220] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
For decades, fisheries have been managed to limit the accidental capture of vulnerable species and many of these populations are now rebounding. While encouraging from a conservation perspective, as populations of protected species increase so will bycatch, triggering management actions that limit fishing. Here, we show that despite extensive regulations to limit sea turtle bycatch in a coastal gillnet fishery on the eastern United States, the catch per trip of Kemp's ridley has increased by more than 300% and green turtles by more than 650% (2001-2016). These bycatch rates closely track regional indices of turtle abundance, which are a function of increased reproductive output at distant nesting sites and the oceanic dispersal of juveniles to near shore habitats. The regulations imposed to help protect turtles have decreased fishing effort and harvest by more than 50%. Given uncertainty in the population status of sea turtles, however, simply removing protections is unwarranted. Stock-assessment models for sea turtles must be developed to determine what level of mortality can be sustained while balancing continued turtle population growth and fishing opportunity. Implementation of management targets should involve federal and state managers partnering with specific fisheries to develop bycatch reduction plans that are proportional to their impact on turtles.
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22
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Page-Karjian A, Chabot R, Stacy NI, Morgan AS, Valverde RA, Stewart S, Coppenrath CM, Manire CA, Herbst LH, Gregory CR, Ritchie BW, Perrault JR. Comprehensive health assessment of green turtles Chelonia mydas nesting in southeastern Florida, USA. ENDANGER SPECIES RES 2020. [DOI: 10.3354/esr01036] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Important indicators of population health needed for large-scale sea turtle population recovery efforts include demographics, disease and mortality trends, condition indices, and baseline blood data. With this comprehensive health assessment of adult female green sea turtles Chelonia mydas nesting on Juno Beach, Florida, USA, we (1) established comprehensive baseline health indices; (2) identified individuals with evidence of infection by chelonid alphaherpesviruses 5 and 6 (ChHV5, ChHV6), which are implicated in fibropapillomatosis and respiratory and skin disease, respectively; and (3) compared measured health indices between turtles that did versus those that did not test positive for ChHV5 and/or ChHV6. All 60 turtles included in the study were in good body condition with no external fibropapillomatosis tumors. Hematological and biochemical reference intervals were established. Via quantitative PCR (qPCR), 5/60 turtles (8%) tested positive for ChHV5, and all turtles were negative for ChHV6. Of 41 turtles tested for antibodies to ChHV5 and ChHV6, 29% and 15% tested positive, respectively, and 10% tested positive for antibodies to both viruses. Notably, there were no statistically significant differences between health variables for nesting turtles that tested positive for ChHV5 DNA versus those that tested negative; and also no differences between turtles that tested positive for ChHV5 or ChHV6 antibodies and those that did not. This suggests that these viruses are enzootically stable in Florida’s adult green turtles. This study provides a health profile of nesting green turtles in southeastern Florida applicable to temporal and spatial investigations of this and other populations.
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Affiliation(s)
- A Page-Karjian
- Florida Atlantic University, Harbor Branch Oceanographic Institute, Fort Pierce, Florida 34946, USA
| | - R Chabot
- Inwater Research Group, Jensen Beach, Florida 34957, USA
| | - NI Stacy
- Aquatic, Amphibian, and Reptile Pathology Program, Department of Comparative, Diagnostic, and Population Medicine, University of Florida College of Veterinary Medicine, Gainesville, Florida 32608, USA
| | - AS Morgan
- Florida Atlantic University, Harbor Branch Oceanographic Institute, Fort Pierce, Florida 34946, USA
| | - RA Valverde
- Southeastern Louisiana University, Hammond, Louisiana 70402, USA
- Sea Turtle Conservancy, Gainesville, Florida 32609, USA
| | - S Stewart
- Southeastern Louisiana University, Hammond, Louisiana 70402, USA
| | - CM Coppenrath
- Loggerhead Marinelife Center, Juno Beach, Florida 33408, USA
| | - CA Manire
- Loggerhead Marinelife Center, Juno Beach, Florida 33408, USA
| | - LH Herbst
- Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - CR Gregory
- Infectious Diseases Laboratory, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, USA
| | - BW Ritchie
- Infectious Diseases Laboratory, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, USA
| | - JR Perrault
- Loggerhead Marinelife Center, Juno Beach, Florida 33408, USA
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23
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Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago. ORYX 2020. [DOI: 10.1017/s0030605319001108] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AbstractGlobal marine turtle population assessments highlight the importance of the south-west Indian Ocean region, despite data gaps for the Chagos Archipelago. The archipelago hosts nesting hawksbill Eretmochelys imbricata and green turtles Chelonia mydas, both heavily exploited for 2 centuries until protection in 1968–1970. We assessed available nesting habitat and spatial distribution of nesting activity during rapid surveys of 90% of the archipelago's coastline in 1996, 1999, 2006 and 2016. We quantified seasonality and mean annual egg clutch production from monthly track counts during 2006–2018 along a 2.8 km index beach on Diego Garcia island. An estimated 56% (132 km) of coastline provided suitable nesting habitat. Diego Garcia and Peros Banhos atolls accounted for 90.4% of hawksbill and 70.4% of green turtle nesting. Hawksbill turtles showed distinct nesting peaks during October–February, and green turtles nested year-round with elevated activity during June–October. Estimates of 6,300 hawksbill and 20,500 green turtle clutches laid annually during 2011–2018 indicate that nesting on the Chagos Archipelago has increased 2–5 times for hawksbill turtles and 4–9 times for green turtles since 1996. Regional estimates indicate green turtles produce 10 times more egg clutches than hawksbill turtles, and the Chagos Archipelago accounts for 39–51% of an estimated 12,500–16,000 hawksbill and 14–20% of an estimated 104,000–143,500 green turtle clutches laid in the south-west Indian Ocean. The improved status may reflect > 40 years without significant exploitation. Long-term monitoring is needed to captureinterannual variation in nesting numbers and minimize uncertainty in population estimates.
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24
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Casale P, Ceriani SA. Sea turtle populations are overestimated worldwide from remigration intervals: correction for bias. ENDANGER SPECIES RES 2020. [DOI: 10.3354/esr01019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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25
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Shimada T, Limpus CJ, Hamann M, Bell I, Esteban N, Groom R, Hays GC. Fidelity to foraging sites after long migrations. J Anim Ecol 2019; 89:1008-1016. [PMID: 31785174 DOI: 10.1111/1365-2656.13157] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/20/2019] [Indexed: 11/28/2022]
Abstract
Patterns of animal movement associated with foraging lie at the heart of many ecological studies and often animals face decisions of staying in an environment they know versus relocating to new sites. The lack of knowledge of new foraging sites means there is risk associated with a decision to relocate (e.g. poor foraging) as well as a potential benefit (e.g. improved foraging). Using a unique long-term satellite tracking dataset for several sea turtle species, combined with capture-mark-recapture data extending over 50 years, we show how, across species, individuals generally maintain tight fidelity to specific foraging sites after extended (up to almost 10,000 km) migration to and from distant breeding sites as well as across many decades. Migrating individuals often travelled through suitable foraging areas en route to their 'home' site and so extended their journeys to maintain foraging site fidelity. We explore the likely mechanistic underpinnings of this trait, which is also seen in some migrating birds, and suggest that individuals will forgo areas of suitable forage encountered en route during migration when they have poor knowledge of the long-term suitability of those sites, making relocation to those sites risky.
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Affiliation(s)
- Takahiro Shimada
- College of Science and Engineering, James Cook University, Townsville, Qld, Australia.,Australian Institute of Marine Science, Crawley, WA, Australia
| | - Colin J Limpus
- Threatened Species Unit, Department of Environment and Science, Queensland Government, Brisbane, Qld, Australia
| | - Mark Hamann
- College of Science and Engineering, James Cook University, Townsville, Qld, Australia
| | - Ian Bell
- Threatened Species Unit, Department of Environment and Science, Queensland Government, Brisbane, Qld, Australia
| | - Nicole Esteban
- Department of Biosciences, Swansea University, Swansea, UK
| | - Rachel Groom
- Department of Environment and Natural Resources, Northern Territory Government of Australia, Palmerston, NT, Australia
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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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27
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Clyde-Brockway C, Robinson NJ, Blanco GS, Morreale SJ, Spotila JR, Tomillo PS, Paladino FV. Local Variation in the Internesting Behavior of Green Turtles in the Gulf of Papagayo, Costa Rica. CHELONIAN CONSERVATION AND BIOLOGY 2019. [DOI: 10.2744/ccb-1352.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Chelsea Clyde-Brockway
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana 47907 USA []
| | | | - Gabriela S. Blanco
- Instituto de Biología de Organismos Marinos, CCT CONICET-CENPAT, Puerto Madryn, Argentina []
| | - Stephen J. Morreale
- Department of Natural Resources, Cornell University, Ithaca, New York 14853 USA []
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28
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Conservation importance of previously undescribed abundance trends: increase in loggerhead turtle numbers nesting on an Atlantic island. ORYX 2019. [DOI: 10.1017/s0030605318001497] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AbstractFor many species abundance data from across their entire range are incomplete, and therefore it is difficult to accurately assess their conservation status. Even for species that are large, charismatic and relatively easy to study, conservation assessments are often hampered by lack of data. Here we report a marked, previously undescribed, increase in numbers at a breeding colony of the loggerhead turtle Caretta caretta, a species that is Critically Endangered in several parts of its range, and place this report in the global context for this species. We present a 10-year (2008–2017) dataset of nesting activities for this species on the island of Sal, one of the Cape Verde islands in the Atlantic Ocean. Foot patrols recorded 21,938 nests during the study period. We estimate that the annual number of nests on Sal increased from 506 in 2008 to 7,771 in 2017. Taking into account that there are only two known loggerhead turtle rookeries (on Masirah Island, Oman, and in Florida, USA) with > 50,000 nests reported annually, and few with > 1,000 nests per year, our results suggest that Sal is one of the 10 largest loggerhead turtle rookeries globally. Our work highlights the conservation significance of reporting trends in abundance at breeding sites for marine turtles and other taxa.
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Piacenza SE, Richards PM, Heppell SS. Fathoming sea turtles: monitoring strategy evaluation to improve conservation status assessments. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01942. [PMID: 31267602 PMCID: PMC6851787 DOI: 10.1002/eap.1942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 04/18/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Population monitoring must be accurate and reliable to correctly classify population status. For sea turtles, nesting beach surveys are often the only population-level surveys that are accessible. However, process and observation errors, compounded by delayed maturity, obscure the relationship between trends on the nesting beach and the population. We present a simulation-based tool, monitoring strategy evaluation (MoSE), to test the relationships between monitoring data and assessment accuracy, using green sea turtles, Chelonia mydas, as a case study. To explore this first application of MoSE, we apply different treatments of population impacts to virtual true populations, and sample the nests or nesters, with observation error, to test if the observation data can be used to diagnose population status accurately. Based on the observed data, we examine population trend and compare it to the known values from the operating model. We ran a series of scenarios including harvest impacts, cyclical breeding probability, and sampling biases, to see how these factors impact accuracy in estimating population trend. We explored the necessary duration of monitoring for accurate trend estimation and the probability of a false trend diagnosis. Our results suggest that disturbance type and severity can have important and persistent effects on the accuracy of population assessments drawn from monitoring nesting beaches. The underlying population phase, age classes disturbed, and impact severity influenced the accuracy of estimating population trend. At least 10 yr of monitoring data is necessary to estimate population trend accurately, and >20 yr if juvenile age classes were disturbed and the population is recovering. In general, there is a greater probability of making a false positive trend diagnosis than a false negative, but this depends on impact type and severity, population phase, and sampling duration. Improving detection rates to 90% does little to lower probability of a false trend diagnosis with shorter monitoring spans. Altogether, monitoring strategies for specific populations may be tailored based on the impact history, population phase, and environmental drivers. The MoSE is an important framework for analysis through simulation that can comprehensively test population assessments for accuracy and inform policy recommendations regarding the best monitoring strategies.
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Affiliation(s)
- Susan E. Piacenza
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon97330USA
- Present address:
Department of BiologyUniversity of West FloridaPensacolaFlorida32514USA
| | - Paul M. Richards
- NOAA NMFS, Southeast Fisheries Science CenterMiamiFlorida33149USA
| | - Selina S. Heppell
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon97330USA
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Sequeira AMM, Heupel MR, Lea MA, Eguíluz VM, Duarte CM, Meekan MG, Thums M, Calich HJ, Carmichael RH, Costa DP, Ferreira LC, Fernandéz-Gracia J, Harcourt R, Harrison AL, Jonsen I, McMahon CR, Sims DW, Wilson RP, Hays GC. The importance of sample size in marine megafauna tagging studies. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01947. [PMID: 31183944 DOI: 10.1002/eap.1947] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/10/2019] [Accepted: 04/17/2019] [Indexed: 06/09/2023]
Abstract
Telemetry is a key, widely used tool to understand marine megafauna distribution, habitat use, behavior, and physiology; however, a critical question remains: "How many animals should be tracked to acquire meaningful data sets?" This question has wide-ranging implications including considerations of statistical power, animal ethics, logistics, and cost. While power analyses can inform sample sizes needed for statistical significance, they require some initial data inputs that are often unavailable. To inform the planning of telemetry and biologging studies of marine megafauna where few or no data are available or where resources are limited, we reviewed the types of information that have been obtained in previously published studies using different sample sizes. We considered sample sizes from one to >100 individuals and synthesized empirical findings, detailing the information that can be gathered with increasing sample sizes. We complement this review with simulations, using real data, to show the impact of sample size when trying to address various research questions in movement ecology of marine megafauna. We also highlight the value of collaborative, synthetic studies to enhance sample sizes and broaden the range, scale, and scope of questions that can be answered.
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Affiliation(s)
- A M M Sequeira
- IOMRC and The University of Western Australia Oceans Institute, School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - M R Heupel
- Australian Institute of Marine Science, PMB No 3, Townsville, Queensland, 4810, Australia
| | - M-A Lea
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Hobart, Tasmania, 7000, Australia
| | - V M Eguíluz
- Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC - UIB), E-07122, Palma de Mallorca, Spain
| | - C M Duarte
- Red Sea Research Centre (RSRC), King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - M G Meekan
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre (M096), University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - M Thums
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre (M096), University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - H J Calich
- IOMRC and The University of Western Australia Oceans Institute, Oceans Graduate School, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - R H Carmichael
- Dauphin Island Sea Lab and, University of South Alabama, 101 Bienville Boulevard, Dauphin Island, Alabama, 36528, USA
| | - D P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, 95060, USA
| | - L C Ferreira
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre (M096), University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - J Fernandéz-Gracia
- Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC - UIB), E-07122, Palma de Mallorca, Spain
| | - R Harcourt
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - A-L Harrison
- Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, PO Box 37012 MRC 5503 MBC, Washington, D.C., 20013, USA
| | - I Jonsen
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - C R McMahon
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
- Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, 2088, New South Wales, Australia
| | - D W Sims
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, United Kingdom
- Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton, Southampton, SO14 3ZH, United Kingdom
| | - R P Wilson
- Department of Biosciences, Swansea University, Swansea, United Kingdom
| | - G C Hays
- Deakin University, Geelong, Victoria, Australia
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Esteban N, Unsworth RKF, Gourlay JBQ, Hays GC. The discovery of deep-water seagrass meadows in a pristine Indian Ocean wilderness revealed by tracking green turtles. MARINE POLLUTION BULLETIN 2018; 134:99-105. [PMID: 29573811 DOI: 10.1016/j.marpolbul.2018.03.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 01/30/2018] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
Our understanding of global seagrass ecosystems comes largely from regions characterized by human impacts with limited data from habitats defined as notionally pristine. Seagrass assessments also largely focus on shallow-water coastal habitats with comparatively few studies on offshore deep-water seagrasses. We satellite tracked green turtles (Chelonia mydas), which are known to forage on seagrasses, to a remote, pristine deep-water environment in the Western Indian Ocean, the Great Chagos Bank, which lies in the heart of one of the world's largest marine protected areas (MPAs). Subsequently we used in-situ SCUBA and baited video surveys to survey the day-time sites occupied by turtles and discovered extensive monospecific seagrass meadows of Thalassodendron ciliatum. At three sites that extended over 128 km, mean seagrass cover was 74% (mean range 67-88% across the 3 sites at depths to 29 m. The mean species richness of fish in seagrass meadows was 11 species per site (mean range 8-14 across the 3 sites). High fish abundance (e.g. Siganus sutor: mean MaxN.site-1 = 38.0, SD = 53.7, n = 5) and large predatory shark (Carcharhinus amblyrhynchos) (mean MaxN.site-1 = 1.5, SD = 0.4, n = 5) were recorded at all sites. Such observations of seagrass meadows with large top predators, are limited in the literature. Given that the Great Chagos Bank extends over approximately 12,500 km2 and many other large deep submerged banks exist across the world's oceans, our results suggest that deep-water seagrass may be far more abundant than previously suspected.
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Affiliation(s)
- N Esteban
- Swansea University, Seagrass Ecosystem Research Group, Department of Biosciences, Swansea SA2 8PP, UK.
| | - R K F Unsworth
- Swansea University, Seagrass Ecosystem Research Group, Department of Biosciences, Swansea SA2 8PP, UK
| | - J B Q Gourlay
- Swansea University, Seagrass Ecosystem Research Group, Department of Biosciences, Swansea SA2 8PP, UK
| | - G C Hays
- Deakin University, Centre for Integrative Ecology, Warrnambool campus, Victoria, Australia
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Hatase H, Omuta K. Nest site selection in loggerhead sea turtles that use different foraging areas: do less fecund oceanic foragers nest at safer sites? J Zool (1987) 2018. [DOI: 10.1111/jzo.12557] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- H. Hatase
- Atmosphere and Ocean Research Institute The University of Tokyo Kashiwa Chiba Japan
| | - K. Omuta
- Yakushima Sea Turtle Research Group Yakushima Kagoshima Japan
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Robinson DP, Jabado RW, Rohner CA, Pierce SJ, Hyland KP, Baverstock WR. Satellite tagging of rehabilitated green sea turtles Chelonia mydas from the United Arab Emirates, including the longest tracked journey for the species. PLoS One 2017; 12:e0184286. [PMID: 28873453 PMCID: PMC5584959 DOI: 10.1371/journal.pone.0184286] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 08/20/2017] [Indexed: 11/21/2022] Open
Abstract
We collected movement data for eight rehabilitated and satellite-tagged green sea turtles Chelonia mydas released off the United Arab Emirates between 2005 and 2013. Rehabilitation periods ranged from 96 to 1353 days (mean = 437 ± 399 days). Seven of the eight tagged turtles survived after release; one turtle was killed by what is thought to be a post-release spear gun wound. The majority of turtles (63%) used shallow-water core habitats and established home ranges between Dubai and Abu Dhabi, the same area in which they had originally washed ashore prior to rescue. Four turtles made movements across international boundaries, highlighting that regional cooperation is necessary for the management of the species. One turtle swam from Fujairah to the Andaman Sea, a total distance of 8283 km, which is the longest published track of a green turtle. This study demonstrates that sea turtles can be successfully reintroduced into the wild after sustaining serious injury and undergoing prolonged periods of intense rehabilitation.
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Affiliation(s)
| | | | | | - Simon J. Pierce
- Marine Megafauna Foundation, Truckee, California, United States of America
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Mazaris AD, Schofield G, Gkazinou C, Almpanidou V, Hays GC. Global sea turtle conservation successes. SCIENCE ADVANCES 2017; 3:e1600730. [PMID: 28948215 PMCID: PMC5606703 DOI: 10.1126/sciadv.1600730] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/24/2017] [Indexed: 05/19/2023]
Abstract
We document a tendency for published estimates of population size in sea turtles to be increasing rather than decreasing across the globe. To examine the population status of the seven species of sea turtle globally, we obtained 299 time series of annual nesting abundance with a total of 4417 annual estimates. The time series ranged in length from 6 to 47 years (mean, 16.2 years). When levels of abundance were summed within regional management units (RMUs) for each species, there were upward trends in 12 RMUs versus downward trends in 5 RMUs. This prevalence of more upward than downward trends was also evident in the individual time series, where we found 95 significant increases in abundance and 35 significant decreases. Adding to this encouraging news for sea turtle conservation, we show that even small sea turtle populations have the capacity to recover, that is, Allee effects appear unimportant. Positive trends in abundance are likely linked to the effective protection of eggs and nesting females, as well as reduced bycatch. However, conservation concerns remain, such as the decline in leatherback turtles in the Eastern and Western Pacific. Furthermore, we also show that, often, time series are too short to identify trends in abundance. Our findings highlight the importance of continued conservation and monitoring efforts that underpin this global conservation success story.
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Affiliation(s)
- Antonios D. Mazaris
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Gail Schofield
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3280, Australia
| | - Chrysoula Gkazinou
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Vasiliki Almpanidou
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Graeme C. Hays
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3280, Australia
- Corresponding author.
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35
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Piacenza SE, Richards PM, Heppell SS. An agent-based model to evaluate recovery times and monitoring strategies to increase accuracy of sea turtle population assessments. Ecol Modell 2017. [DOI: 10.1016/j.ecolmodel.2017.05.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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