Finding of a two-headed green turtle embryo during nest monitoring in Baa Atoll, Maldives

Green sea turtles are one of the two species of marine turtles known to nest in the Maldives. The prevalent time of nesting seems to be inconsistent throughout the island nation. In this study, sea turtle nesting activity was monitored on the island of Coco Palm Dhuni Kolhu in Baa Atoll over a period of 12 months. A total of 13 nests were confirmed with a median hatching success rate of 89.58% as ascertained by nest excavation. In one of the nests, a severely deformed hatchling with polycephaly, an opening in the neck area and a lordotic spine was found, and we investigated in detail with radiographic images and a necropsy. Our findings support the importance of consistent nesting activity and nest monitoring efforts in the country as a basis for conservation efforts.

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The Effect of Invertebrate Infestation on Green Turtle (Chelonia mydas) Nests on Kazanlı Beach, Mersın, Turkey

Russian Journal of Herpetology ◽

10.30906/1026-2296-2020-27-5-245-256 ◽

2020 ◽

Vol 27 (5) ◽

pp. 245-256

Author(s):

Cemil Aymak ◽

Aşkın Hasan Uçar ◽

Yusuf Katılmış ◽

Eyup Başkale ◽

Serap Ergene

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Negative Relationship ◽

Chelonia Mydas ◽

Sea Turtle ◽

Faunal Composition ◽

Independent Variables ◽

Invertebrate Species ◽

First Time ◽

Nesting Season

In this study invertebrate infestation in green turtle (Chelonia mydas) nests were recorded for the first time for Kazanlı beach, Mersin, Turkey. For this aim, in 2006 nesting season, 294 natural intact green turtle nests were sampled to examine their contents and invertebrate infestation was found in 76 (25.85% of the total sampling green turtle nests). These infested nests were examined in terms of the invertebrate faunal composition. The specimens found in the green sea turtle nests were identified to order, family or genus levels and they were represented in 5 orders. These invertebrate groups are Elater sp. larvae (Elateridae; Coleoptera), Pimelia sp. larvae (Tenebrionidae; Coleoptera), Enchytraeidae (Oligochaeta), Cyrptostigmata (Acari), Oniscidae (Isopoda), Formicidae (Hymenoptera). Elater sp. was the most common invertebrate group in the green turtle nests. According to student t test, we found statistically significant differences between 7 independent variables and invertebrate species presence. Furthermore, logistic regression analysis explained that there is a negative relationship between hatching success rate and invertebrate species presence.

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Chelonicola and Poulinea, two new gomphonemoid diatom genera (Bacillariophyta) living on marine turtles from Costa Rica

Phytotaxa ◽

10.11646/phytotaxa.233.3.2 ◽

2015 ◽

Vol 233 (3) ◽

pp. 236 ◽

Cited By ~ 21

Author(s):

Roksana Majewska ◽

J. P. Kociolek ◽

Evan W. Thomas ◽

Mario De Stefano ◽

Mario Santoro ◽

...

Keyword(s):

Costa Rica ◽

Marine Mammals ◽

Sea Turtles ◽

Sea Turtle ◽

New Genera ◽

Olive Ridley ◽

Lepidochelys Olivacea ◽

Marine Turtles ◽

The Family ◽

Long Time

Marine mammals such as whales and dolphins have been known for a long time to host a very specific epizoic community on their skin. Less known however is the presence of a similar community on the carapaces of sea turtles. The present study is the first describing new taxa inhabiting sea turtle carapaces. Samples, collected from nesting olive ridley sea turtles (Lepidochelys olivacea) on Ostional Beach (Costa Rica), were studied using light and scanning electron microscopy. Two unknown small-celled gomphonemoid taxa were analysed in more detail and are described as two new genera, closely related to other gomphonemoid genera with septate girdle bands, such as Tripterion, Cuneolus and Gomphoseptatum. Chelonicola Majewska, De Stefano & Van de Vijver gen. nov. has a flat valve face, uniseriate striae composed of more than three areolae, simple external raphe endings, internally a siliceous flap over the proximal raphe endings and lives on mucilaginous stalks. Poulinea Majewska, De Stefano & Van de Vijver gen. nov. has at least one concave valve, uniseriate striae composed of only two elongated areolae, external distal raphe endings covered by thickened siliceous flaps and lives attached to the substrate by a mucilaginous pad. Chelonicola costaricensis Majewska, De Stefano & Van de Vijver sp. nov. and Poulinea lepidochelicola Majewska, De Stefano & Van de Vijver sp. nov. can be separated based on stria structure, girdle structure composed of more than 10 copulae, raphe structure and general valve outline. A cladistics analysis of putative members of the Rhoicospheniaceae indicates that the family is polyphyletic. Chelonicola and Poulinea are sister taxa, and form a monophyletic group with Cuneolus and Tripterion, but are not closely related to Rhoicosphenia, or other genera previously assigned to this family. Features used to help diagnose the family such as symmetry and presence of septa and pseudosepta are homoplastic across the raphid diatom tree of life.

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Hatching Success Rather Than Temperature-Dependent Sex Determination as the Main Driver of Olive Ridley (Lepidochelys olivacea) Nesting Activity in the Pacific Coast of Central America

Animals ◽

10.3390/ani11113168 ◽

2021 ◽

Vol 11 (11) ◽

pp. 3168

Author(s):

Alejandra Morales Mérida ◽

Aude Helier ◽

Adriana A. Cortés-Gómez ◽

Marc Girondot

Keyword(s):

Solar Radiation ◽

Central America ◽

Pacific Coast ◽

Hatching Success ◽

Temperature Dependent ◽

Lepidochelys Olivacea ◽

Marine Turtles ◽

The Pacific ◽

Main Driver ◽

Nesting Activity

In marine turtles, sex is determined during a precise period during incubation: males are produced at lower temperatures and females at higher temperatures, a phenomenon called temperature-dependent sex determination. Nest temperature depends on many factors, including solar radiation. Albedo is the measure of the proportion of reflected solar radiation, and in terms of sand color, black sand absorbs the most energy, while white sand reflects more solar radiation. Based on this observation, darker sand beaches with higher temperatures should produce more females. As marine turtles show a high degree of philopatry, including natal homing, dark beaches should also produce more female hatchlings that return to nest when mature. When sand color is heterogeneous in a region, we hypothesize that darker beaches would have the most nests. Nevertheless, the high incubation temperature on beaches with a low albedo may result in low hatching success. Using Google Earth images and the SWOT database of nesting olive ridleys (Lepidochelys olivacea) in the Pacific coast of Mexico and Central America, we modeled sand color and nesting activity to test the hypothesis that darker beaches host larger concentrations of females because of feminization on darker beaches and female philopatry. We found the opposite result: the lower hatching success at beaches with a lower albedo could be the main driver of nesting activity heterogeneity for olive ridleys in Central America.

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The Effects of Nest Location and Beach Environment on Hatching Success for Leatherback (Dermochelys Coriacea) and Green (Chelonia Mydas) Sea Turtles on Bioko Island, Equatorial Guinea

10.21203/rs.3.rs-317848/v1 ◽

2021 ◽

Author(s):

Callie A. Veelenturf ◽

Elizabeth M. Sinclair ◽

Peter Leopold ◽

Frank V. Paladino ◽

Shaya Honarvar

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Sea Turtles ◽

Chelonia Mydas ◽

Dermochelys Coriacea ◽

Equatorial Guinea ◽

Leatherback Turtles ◽

Nest Location ◽

Bioko Island ◽

Elevation Range

Abstract Hatching success in sea turtles is hindered by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average clutch hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of experimental nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between -0.286 m to -0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development.

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Red blood cell osmotic fragility in healthy loggerhead and green sea turtles

Journal of Veterinary Diagnostic Investigation ◽

10.1177/1040638720957117 ◽

2020 ◽

Vol 32 (6) ◽

pp. 908-911

Author(s):

Rebecca Radisic ◽

Sean D. Owens ◽

Charles A. Manire ◽

Nicole Montgomery ◽

Doug Mader ◽

...

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Sea Turtles ◽

Osmotic Fragility ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Sea Turtles ◽

Nacl Concentration ◽

Life Threatening ◽

Rehabilitation Facilities

Loggerhead ( Caretta caretta; Cc) and green sea ( Chelonia mydas; Cm) turtles admitted to rehabilitation facilities may require blood transfusions for supportive treatment of disorders resulting in life-threatening anemia, but, considering the unique erythrocyte chemistry of sea turtles, standardized donor red blood cell (RBC) storage protocols have not been established. Prolonged cold storage and the effects of various anticoagulant-preservative solutions have been associated with increased RBC osmotic fragility across a broad range of species. Increased RBC fragility in stored RBC products has been associated with acute transfusion reactions. The osmotic fragility test is used to measure erythrocyte resistance to hemolysis while being exposed to a series of dilutions of a saline solution. We obtained baseline measurements for osmotic fragility in healthy Cc and Cm. Osmotic fragility testing was performed on samples from 10 Cc to 10 Cm. Fifty percent (50%) RBC hemolysis was identified at a mean NaCl concentration of 0.38% in both species. Results of our study will help guide future studies evaluating optimal storage solutions for sea turtle blood products.

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Predation on green sea turtle, Chelonia mydas, hatchlings by invasive rats

Pacific Conservation Biology ◽

10.1071/pc18087 ◽

2019 ◽

Vol 25 (4) ◽

pp. 423 ◽

Cited By ~ 2

Author(s):

Markus Gronwald ◽

Quentin Genet ◽

Margaux Touron

Keyword(s):

Food Source ◽

Sea Turtles ◽

Rattus Rattus ◽

Chelonia Mydas ◽

Sea Turtle ◽

French Polynesia ◽

Camera Traps ◽

Green Sea Turtle ◽

Green Sea Turtles ◽

Invasive Rats

We used camera traps to identify invasive Rattus rattus as predators at a green sea turtle, Chelonia mydas, nest in French Polynesia. The footage shows that the hatchlings are a familiar food source for rats and that the control of invasive rats has to be considered for the protection of endangered green sea turtles.

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Population dynamic between vulnerable coastal jaguars (Panthera onca) and endangered green sea turtles (Chelonia mydas) in Tortuguero National Park, Costa Rica.

10.7287/peerj.preprints.26915 ◽

2018 ◽

Author(s):

Stephanie Butera ◽

Jaime Restrepo

Keyword(s):

National Park ◽

Sea Turtles ◽

Chelonia Mydas ◽

Sea Turtle ◽

Predator Prey ◽

Green Sea Turtles ◽

Turtle Population ◽

Nest Depredation ◽

The Impact ◽

Nest Predators

New-born sea turtles face a number of predators between the time the mothers lay eggs on the beach to when the hatchlings grow into larger juveniles. Nest depredation impacts reproductive success of nesting sea turtles, reducing the number of new turtles that make it to the sea. On Tortuguero beach nest predators include; dogs, coati, and raccoons. Nest depredation within Tortuguero National Park (TNP) has decreased dramatically since 1979. This decrease in nest depredation is linked to the increased jaguar population within TNP as the aforementioned species are considered the jaguars natural prey. Although jaguars prey on nesting turtles, they also control the populations of nest predators. Even more, jaguars have been demonstrated to change their behaviour to suit their preference in prey species therefore the nest predator distribution in TNP was examined to investigate whether changes in jaguar prey preference had an effect. Nest predation and the number of adult turtles lost to jaguar depredation were examined to determine the significance of the threat jaguars pose to the sea turtle population. This study investigates the predator prey relationship between jaguars, nest predators, and nesting female sea turtles; aiming to assessing the impact that jaguars have on the turtle's population.

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Incubation temperatures, hatching success and congenital anomalies in green turtle nests from Guanahacabibes Peninsula, Cuba

AQUATIC RESEARCH ◽

10.3153/ar21027 ◽

2021 ◽

Vol 4 (4) ◽

pp. 321-330

Author(s):

Randy Calderón Peña ◽

Julia Azanza Ricardo

Keyword(s):

Congenital Anomalies ◽

Green Turtle ◽

Thermal Tolerance ◽

Elevated Temperatures ◽

Hatching Success ◽

Incubation Temperature ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Incubation Temperatures

Elevated incubation temperatures of sea turtle nests decrease hatching success and alter the resulting hatchlings' morphology. There is an absence of studies assessing the relationships between temperature and hatching success in Cuba, even when they could improve understanding the limits of thermal tolerance in these species. This study evaluated the influence of incubation temperature on hatching success and phenotypic malformations in green turtle hatchlings (Chelonia mydas); and analyzed the temporal variation in hatching success on the studied beaches. In 48 green turtles nests distributed along two beaches, incubation temperature and hatching success were recorded between 2014 and 2019. Increasing incubation temperature caused a decrease in the hatching success and an increase in the frequency of supernumerary scutes. Despite the elevated temperatures (average > 30°C), hatching was higher than 80%. Significant differences in hatching success were only observed among seasons for nests in Antonio Beach (lower values in 2016 and 2019 compared to 2014).

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Climate change and green sea turtle sex ratio – Preventing possible extinction

10.1101/2020.04.08.032227 ◽

2020 ◽

Author(s):

Jana Blechschmidt ◽

Meike J. Wittmann ◽

Chantal Blüml

Keyword(s):

Climate Change ◽

Sex Ratio ◽

Nest Site ◽

Sea Turtles ◽

Chelonia Mydas ◽

Sea Turtle ◽

Change Scenario ◽

Green Sea Turtles ◽

The Face ◽

Nest Depth

AbstractClimate change poses a threat to species with temperature-dependent sex determination. A recent study on green sea turtles (Chelonia mydas) at the northern Great Barrier Reef (GBR) showed a highly female-skewed sex ratio with almost all juvenile turtles being female. This shortage of males might eventually cause population extinction, unless rapid evolutionary rescue, migration or conservation efforts ensure a sufficient number of males. We built a stochastic individual-based model inspired by C. mydas, but potentially transferrable to other species with TSD. Nest depth, level of shade, and pivotal temperature were evolvable traits. Additionally, we considered the effect of crossbreeding between the northern and southern GBR, nest-site philopatry, and conservation efforts. Among the evolvable traits, nest depth was the most likely to rescue the population in the face of climate change, but even here the more extreme climate-change scenario led to extinction. Surprisingly, nest-site philopatry elevated extinction rates. Conservation efforts to artificially increase nest depth promoted population survival and did not preclude trait evolution. Although extra information is needed to make reliable predictions for the fate of green sea turtles, our results illustrate how evolution can shape the fate of long lived, vulnerable species in the face of climate change.Graphical Abstract

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Lesson to Learn from an Endangered Green Turtle (Chelonia mydas): Marine Debris Ingestion, Rehabilitation and Satellite Tracking

Indian Journal of Animal Research ◽

10.18805/ijar.b-1246 ◽

2020 ◽

Author(s):

Tsung-Hsien Li ◽

Ya-Ru Cai ◽

Po-Yu Wu ◽

Connie Ka-Yan Ng ◽

George H. Balazs

Keyword(s):

Green Turtle ◽

Marine Pollution ◽

Sea Turtles ◽

Public Awareness ◽

Chelonia Mydas ◽

Sea Turtle ◽

Marine Debris ◽

Satellite Transmitter ◽

Pollution Problem ◽

Environmental Pollution Problem

Background: Marine debris is an environmental pollution problem affecting the oceans worldwide. Recent studies reveal that marine debris ingestion by sea turtles is rising. Sea turtles brought in for rehabilitation allows an opportunity to provide insights into the possible effects of anthropogenic debris on animal’s survivorship during rehabilitation. Methods: A green turtle (Chelonia mydas) was bycaught in fishing gear in south-western Taiwan in 2016. Debris were collected in the holding tank during rehabilitation. After a 3-month rehabilitation, the turtle was fit for release. Prior to the release, the turtle was tagged with a satellite transmitter. Result: Marine debris were found in turtle feces or floating on the surface of basins during rehabilitation. The debris were dominated by fishing line, hard plastic, soft plastic, rope, wood and styrofoam. The turtle survived and was successfully released back into the wild attached with a satellite transmitter. The turtle remained residing in waters of southern Taiwan, possibly its foraging ground, for almost two months. This study presents an apparent successful rehabilitation of an endangered green sea turtle, that hopefully helps further enhance environmental education and public awareness, as well as concerted actions against marine pollution in general and anthropogenic debris related problems in particular.

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