Ontogeny of Marine Turtle Gonads

AbstractDietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles (n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles (n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.

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Critical In-Water Habitats for Post-Nesting Sea Turtles from the Southern Gulf of Mexico

Journal of Marine Science and Engineering ◽

10.3390/jmse9080793 ◽

2021 ◽

Vol 9 (8) ◽

pp. 793

Author(s):

Abigail Uribe-Martínez ◽

María de los Angeles Liceaga-Correa ◽

Eduardo Cuevas

Keyword(s):

Gulf Of Mexico ◽

Marine Ecosystem ◽

Satellite Telemetry ◽

Marine Turtle ◽

Home Ranges ◽

The Bahamas ◽

Turtle Species ◽

Southern Gulf Of Mexico ◽

Large Marine Ecosystem ◽

Physical Features

Marine turtles are globally endangered species that spend more than 95% of their life cycle in in-water habitats. Nevertheless, most of the conservation, recovery and research efforts have targeted the on-land habitats, due to their easier access, where adult females lay their eggs. Targeting the large knowledge gaps on the in-water critical habitats of turtles, particularly in the Large Marine Ecosystem Gulf of Mexico, is crucial for their conservation and recovery in the long term. We used satellite telemetry to track 85 nesting females from their beaches after they nested to identify their feeding and residency habitats, their migratory corridors and to describe the context for those areas. We delimited major migratory corridors in the southern Gulf of Mexico and West Caribbean and described physical features of internesting and feeding home ranges located mainly around the Yucatan Peninsula and Veracruz, Mexico. We also contributed by describing general aggregation and movement patterns for the four marine turtle species in the Atlantic, expanding the knowledge of the studied species. Several tracked individuals emigrated from the Gulf of Mexico to as far as Nicaragua, Honduras, and the Bahamas. This information is critical for identifying gaps in marine protection and for deciphering the spatial connectivity in large ocean basins, and it provides an opportunity to assess potential impacts on marine turtle populations and their habitats.

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Plastic ingestion by freshwater turtles: a review and call to action

Scientific Reports ◽

10.1038/s41598-021-84846-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Adam G. Clause ◽

Aaron J. Celestian ◽

Gregory B. Pauly

Keyword(s):

Marine Species ◽

Marine Turtle ◽

Freshwater Turtle ◽

Freshwater Turtles ◽

Plastic Pollution ◽

Potential Threat ◽

Implementation Quality ◽

Turtle Species ◽

Marine Turtles ◽

Conservation Concern

AbstractPlastic pollution, and especially plastic ingestion by animals, is a serious global issue. This problem is well documented in marine systems, but it is relatively understudied in freshwater systems. For turtles, it is unknown how plastic ingestion compares between marine and non-marine species. We review the relevant turtle dietary literature, and find that plastic ingestion is reported for all 7 marine turtle species, but only 5 of 352 non-marine turtle species. In the last 10 years, despite marine turtles representing just 2% of all turtle species, almost 50% of relevant turtle dietary studies involved only marine turtles. These results suggest that the potential threat of plastic ingestion is poorly studied in non-marine turtles. We also examine plastic ingestion frequency in a freshwater turtle population, finding that 7.7% of 65 turtles had ingested plastic. However, plastic-resembling organic material would have inflated our frequency results up to 40% higher were it not for verification using Raman spectroscopy. Additionally, we showcase how non-native turtles can be used as a proxy for understanding the potential for plastic ingestion by co-occurring native turtles of conservation concern. We conclude with recommendations for how scientists studying non-marine turtles can improve the implementation, quality, and discoverability of plastic ingestion research.

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Status of Marine Turtles in British Columbia Waters: A Reassessment

The Canadian Field-Naturalist ◽

10.22621/cfn.v118i1.885 ◽

2004 ◽

Vol 118 (1) ◽

pp. 72 ◽

Cited By ~ 3

Author(s):

Donald F. McAlpine ◽

Stan A. Orchard ◽

Kelly A. Sendall ◽

Rod Palm

Keyword(s):

British Columbia ◽

Marine Environment ◽

Chelonia Mydas ◽

Marine Turtle ◽

Dermochelys Coriacea ◽

Concerted Effort ◽

Leatherback Turtles ◽

Marine Turtles ◽

Green Turtles

Marine turtles in British Columbia have previously been considered off course stragglers. Here we document 20 new reports for Green Turtles, Chelonia mydas, and Leatherback Turtles, Dermochelys coriacea, for the province. Until recently there had been no concerted effort to acquire data on marine turtle abundance or frequency off British Columbia. Observations presented here allow a reassessment of marine turtle status in British Columbia waters. We suggest Green Turtles and Leatherbacks should be considered rare vagrants and uncommon seasonal residents, respectively, off British Columbia and that they are a natural part of the British Columbia marine environment.

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Hatchlings of the Marine Turtle Lepidochelys olivacea Display Signs of Prenatal Stress at Emergence after Being Incubated in Man-Made Nests: A Preliminary Report

Frontiers in Marine Science ◽

10.3389/fmars.2017.00400 ◽

2017 ◽

Vol 4 ◽

Cited By ~ 1

Author(s):

Ma. A. Herrera-Vargas ◽

Esperanza Meléndez-Herrera ◽

Gabriel Gutiérrez-Ospina ◽

Fany E. Bucio-Piña ◽

Armida Báez-Saldaña ◽

...

Keyword(s):

Prenatal Stress ◽

Preliminary Report ◽

Marine Turtle ◽

Lepidochelys Olivacea

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Natal foraging philopatry in eastern Pacific hawksbill turtles

Royal Society Open Science ◽

10.1098/rsos.170153 ◽

2017 ◽

Vol 4 (8) ◽

pp. 170153 ◽

Cited By ~ 6

Author(s):

Alexander R. Gaos ◽

Rebecca L. Lewison ◽

Michael P. Jensen ◽

Michael J. Liles ◽

Ana Henriquez ◽

...

Keyword(s):

Genetic Research ◽

Eastern Pacific ◽

Marine Turtle ◽

Natal Philopatry ◽

Eretmochelys Imbricata ◽

Turtle Species ◽

Marine Turtles ◽

Complex Processes ◽

Natal Homing ◽

Hawksbill Turtles

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

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Late Cretaceous non-marine turtles of Asia: a review of taxonomic diversity and paleobiogeography

10.7287/peerj.preprints.1087 ◽

2015 ◽

Author(s):

Igor Danilov ◽

Ekaterina Obraztsova ◽

Vladimir Sukhanov

Keyword(s):

Late Cretaceous ◽

Environmental Conditions ◽

Geographical Area ◽

Temporal Distribution ◽

Taxonomic Diversity ◽

Coastal Areas ◽

Marine Turtle ◽

Marine Turtles ◽

Middle Asia ◽

Different Ages

Background. This report reviews data on taxonomic diversity and paleobiogeography of Late Cretaceous (K2) non-marine turtles of Asia accumulated since latest reviews in 2000s. K2 non-marine turtles of Asia are known from four main geographical areas: Middle Asia-Kazakhstan (MAK), Mongolia (MO), China (CH) and Japan (JA). Methods. We critically reviewed composition of non-marine turtle assemblages of the K2 for each of the mentioned geographical area to make estimates of taxonomic diversity for different ages of the K2. Based on these data we analyzed temporal distribution of taxa of non-marine turtles and change in taxonomic diversity of turtle assemblages. Results. K2 turtles of MAK are represented by eight suprageneric taxa – Adocidae (Ad), Carettochelyidae (Ca), Lindholmemydidae (Li), Macrobaenidae (Ma), Nanhsiungchelyidae (Na), Trionychidae (Tr), Eucryptodira indet. (Eu), and Testudines indet. (Te), of which Ad, Li, Ma and Tr are known from the Cenomanian(CE) – early Campanian(CA), whereas other taxa only from the CE-early Turonian(TU). Taxonomic diversity changes from 10–12 species and genera, 6–8 suprageneric taxa in the CE to 7 species and genera, 4 families in the late TU early CA. K2 turtles of MO are represented by seven suprageneric taxa – Ad, Ca, Li, Ma, Meiolaniformes (Me), Na, and Tr, of which Li, Na and Tr are known from the CE-Maastrichtian(MA), Ad, Ca, and Ma, from the CE-Santonian(SA), and Me, only from the MA. Taxonomic diversity changes from 12 species, 10 genera, 6 families in the CE – SA, 8–9 species, 7–9 genera, 3 families in the CA, and 9 species, 7–8 genera, and 4 suprageneric taxa in the MA. K2 turtles of CH are represented by three suprageneric taxa (Li, Na, and Tr), but their precise temporal distribution is poorly known. Taxonomic diversity in the K2 is 12 species, 11–12 genera, and 3 families. K2 turtles of JA are represented by six suprageneric taxa (Ad, Ca, Na, Tr, Eu, and Te), of which Na are known from the CE-SA, Tr from the Coniacian(CO)-CA, and other taxa from the CO-SA. Taxonomic diversity changes from 1 species, genus, and family in the CE-TU to 7 species and genera, and 5–6 suprageneric taxa in the CO-SA. Discussion. In MAK, most significant transformation of turtle assemblages occurred in the CE-TU, whereas transformation in the SA-CA was less significant. On the contrary, in MO, most significant transformation occurred in the SA-CA, and less significant in the CA-MA.The patterns of transformation of the K2 turtle assemblages of CH and JA are not clear. The differences in the patterns of diversity and transformations of the K2 turtle assemblages in different geographical areas of Asia may be explained by different environmental conditions in these areas at that time and influence of such factors as transgressions in coastal areas (MAK and JA) and cooling and aridizations in inland areas (MO and CH).

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The Olive Ridley Project (ORP): A successful example of how to engage researchers, conservation practitioners and civil society

Research for All ◽

10.14324/rfa.05.2.17 ◽

2021 ◽

Vol 5 (2) ◽

Author(s):

Martin Stelfox ◽

Mercedes Martin-Cereceda ◽

Karim Vahed ◽

Jillian Hudgins ◽

Stephanie Köhnk ◽

...

Keyword(s):

Spatial Ecology ◽

Community Education ◽

Knowledge Exchange ◽

Sustainable Use ◽

Sea Turtle ◽

Marine Turtle ◽

Olive Ridley ◽

Turtle Species ◽

Research Engagement ◽

The Uk

The Olive Ridley Project (ORP) was set up to protect sea turtles and their habitats. The project was formed in 2013, and it became a registered charity in the UK in 2016. From its inception, ORP took a multidisciplinary approach to achieve its goals. Part of its objectives, and the reason why the charity came to fruition, are related to the issue of olive ridley sea turtle (Lepidochelys olivacea) entanglement in abandoned, lost or discarded fishing gear (also known as ‘ghost gear’ or ‘ghost nets’), and the search for ghost gear and turtle entanglement ‘hot spots’ throughout the Indian Ocean. The initial ORP research questions were soon challenged by societal interests to develop inclusive educational programmes in local communities and tourist resorts that could raise awareness about the need for conservation of all sea turtle species. In February 2017, ORP opened the first veterinarian-run, fully equipped Marine Turtle Rescue Centre in the Maldives, bringing together the work of researchers, citizen scientists, volunteers, environmentalists, marine biologists and veterinarians. The present work of ORP sits on a strong and scientifically robust collaborative plan. Current ORP research projects range from sea turtle population analyses, spatial ecology, rehabilitation of injured and sick individuals, epibiont parasite analyses, precise turtle identification through photo-ID research, linking ghost gear to responsible fisheries, and analyses of ghost gear drift patterns. The programme enhances community education and outreach by engaging schoolchildren, organizing workshops, promoting sustainable use of ghost gear waste, and training citizen scientists and local fishing communities. The ORP programme encompasses many principles of research engagement, effectively combining scientific knowledge, education and action. This article explores all stages of the process (from research planning and design, to knowledge exchange and inter- and trans-disciplinary impact assessments), describing the active engagement originated by the ORP initiative. A reflective insight into the learning, enrichment and challenges of engaging researchers and community actors is also included, considering the current social and scientific framework.

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