Turtle Research Articles

Maternal diet influences fecundity in a freshwater turtle undergoing population decline.

Food availability determines the amount of energy animals can acquire and allocate to reproduction and other necessary functions. Female animals that are food limited thus experience reduced energy available for reproduction. When this occurs, females may reduce frequency of reproductive events or the number or size of offspring per reproductive bout. We assessed how maternal diet affects reproductive output in adult female Murray River short-necked turtles, Emydura macquarii, from four wetlands in Victoria. We previously found that turtle diets differ in the composition of plants and animals between our study wetlands. In this study, we tested whether differences in turtle diet composition (i.e. plants and animals) at these wetlands were associated with differences in clutch mass, individual egg mass, bulk egg composition and hatching success. We found total clutch mass increased with maternal body size at each site. At sites where filamentous green algae were scarce and E. macquarii were carnivorous, females produced smaller clutches relative to body size compared to females from sites where algae were abundant, and turtles were more herbivorous. Individual egg mass, bulk egg composition and hatching success did not differ across wetlands. Isotopic analysis revealed significant positive relationships between the carbon and nitrogen isotopes (δ13C, δ15N) of the eggs and those of the mothers, indicating that mothers allocated ratios of carbon and nitrogen isotopes to their eggs similar to those present in their tissues. Our study suggests that at sites where females are more carnivorous due to a relative absence of algae, females produce smaller clutches, but other aspects of their reproduction are not significantly impacted. The reduction in clutch size associated with differences in the availability of dietary plants and animals may have long-term consequences for E. macquarii and other freshwater turtle species that are experiencing population declines.

Closing the knowledge gap: Helminth parasites of freshwater turtles from the Chaco-Pampa Plain, Southern South America.

Six species of freshwater turtles dominate the Chaco-Pampa Plain in southern South America and their parasites have been relatively understudied, with most records concentrated in Brazil. Particularly in Argentina, there are only scattered records of parasites for most of the turtles that inhabit the region, leaving a large knowledge gap. The purpose of the present contribution is to increase the knowledge of the internal parasites of six species of freshwater turtles from Argentina, after 15 years of fieldwork, by providing new hosts and additional geographic records for many host-parasite relationships. Some molecular sequences of the studied parasites were provided as a tool for better species identification. We processed 433 stomach and fecal samples from live individuals and visceral and soft tissue samples from 54 dissected turtles collected from a wide range and different ecoregions. We found 6230 helminths belonging to 18 taxa (one cestode, 11 digeneans and six nematodes). Fourteen new parasite-host associations are reported here, and for the first time parasites are recorded for Phrynops williamsi. This work contributes significantly to the knowledge of the parasitofauna in freshwater turtles in Argentina, providing a detailed list of parasites present in each turtle species and reporting molecular characters for future studies.

Depredation of eggs of threatened freshwater turtles by the short-beaked echidna (Tachyglossus aculeatus (Shaw, 1792))

The echidna (Tachyglossus aculeatus) is documented as a new native predator of freshwater turtle eggs, particularly those of the vulnerable Fitzroy River turtle (Rheodytes leukops), and the critically endangered white-throated snapping turtle (Elseya albagula). This depredation has been identified in the Fitzroy, Burnett and Mary Catchments with echidnas recorded at traditional turtle nesting banks using direct observation of depredation of eggs, remote camera footage and identification of tracks. Echidnas were observed at traditional nesting banks for E. albagula and R. leukops nesting across eight months of the year. The presence of echidnas was more frequent during the R. leukops nesting season in spring. R. leukops is endemic to the Fitzroy Catchment and the depredation rate of eggs was significantly higher than for other species and catchments. The mean top egg depth of R. leukops nests was found to be the same depth as the echidna’s beak length. There was a significant increase in depredation during the five-year study period, with 47.4% of R. leukops clutches depredated by echidna in the 2022 season. This substantial loss of eggs and recruitment of hatchling turtles poses a significant threat to the populations of this threatened species.

Impact of severe drought on movement and survival of freshwater turtles in the Gwydir Wetlands, Australia

Impact of severe drought on movement and survival of freshwater turtles in the Gwydir Wetlands, Australia

A novel approach to urban turtle sampling: Assessing Hookless Fishing with clip and two conventional methods.

To address urban turtle sampling challenges, we presented Hookless fishing with clip, a cost-effective method for sampling this important group. Effectiveness, biases and potential advantages were analysed in comparison to two commonly used methods (funnel trap and hand capture). Fieldwork was conducted between August and November/2021 in four areas in Brazil, using the three methods simultaneously. A total of 195 turtles from four species (Phrynops geoffroanus, Hydromedusa tectifera, Trachemys dorbigni and T. scripta elegans) were captured. Funnel trap demonstrate a significantly higher capture than hand capture, while Hookless fishing showed no significant difference in captures compared to funnel trap. The highest catch per unit effort values were observed for the new method (0.37) and the funnel trap (0.34). Despite being widely used, funnel traps were the only method to exhibit male bias. Our findings revealed that Hookless fishing with clip exhibited remarkable capture efficiency, cost-effectiveness, and ease of transport and utilization; however, it requires operator presence. Nevertheless, the proposed method, both as the primary or auxiliary approach, appears efficient in enhancing captures and reducing costs and risks. This innovative method has the potential to assist researchers studying omnivorous and carnivores freshwater turtles in environments worldwide, especially in human settlements.

What Is the True “Papa” Turtle? A Discussion About the Origin of The Clade Testudines from Both Morphological and Molecular Perspectives

Turtles, from the order Testudines has a debatable origin. The oldest defined species of the order was Proganochelys quenstedti from the late Triassic. However, the origin or the ancestor of this species has been a hot topic among scientists. This paper discussed the potential origin of the turtles using both the morphological and molecular perspectives. Based on the morphological evidence for the evolution of the defining features, one theory suggested that this order originated from the Eunotosaurus africanus which the dorsal ribs fused together first; other theories suggested that it originated from Odontocheyls semi Testacea which the ventral ribs fused first. The skull structure is another debatable topic as evolutionary evidence which the current turtles are classified as anapsid due to its lack of temporal fenestration. However, many of the potential ancestors showed defining two fenestrations of diapsids or at least some features indicating it was evolving into anapsid. The molecular evidence of mitochondrion cDNA showed that the Testudines clade diverged from the other Archosauri in Jurassic which completely overthrow all the hypothesis. Although morphological based theory has its flaw, it was a more convincing theory than the molecular based theory. As some studies suggested that the Odontotomy’s semi Testacea could lost its dorsal shell inherited from its ancestor, the hypothesized evolutionary route is E. africanus àPappocheyl. rosinae àO. semitestaceaàP. quenstedti.

Implications of Climatic Drying on the Nesting Triggers for a Freshwater Turtle

Implications of Climatic Drying on the Nesting Triggers for a Freshwater Turtle

Goldfish or aquatic turtle? Impact of two animal assisted interventions on children's pain, anxiety, and fear during IV catheterization: A randomized controlled trial

PurposeThis study aimed to determine the effect of goldfish and aquatic turtle nursing interventions on children's pain, anxiety, and fear during IV catheter insertion. Design and methodsThe randomized controlled trial included 98 children (control group = 32, goldfish group = 33, aquatic turtle group = 33) aged 5–6 years, attending outpatient clinic for blood sampling and catheterisation procedures. Pain was measured using the Wong Baker Facial Pain Scale, anxiety was measured using the Child Anxiety Scale-State, and child fear was measured using the Child Fear Scale, before, during, and after catheterization. ResultsWhen analyzing the pain, anxiety, and fear findings, no statistical difference was found between the scores of the mother, child, and researcher before the procedure. During the catheterization procedure, the pain, anxiety, and fear scores of the children in the fish and turtle groups increased statistically less than those in the control group. When analyzing the post-procedure findings, the pain, anxiety, and fear scores of the control group were similar to those before the procedure. In the fish and turtle groups, anxiety and fear scores were statistically the lowest (p < 0.05). ConclusionIt can be concluded that animal-assisted practices reduce anxiety and fear during and after the catheterization procedures while diverting attention from pain. Practice implicationsGoldfish or aquatic turtle intervention improve children's attitudes toward pain, anxiety, and fear during IV catheter insertion. Pediatric nurses could consider incorporating, such as the animal assisted intervention, into their clinical practice to reduce the pain, anxiety, and fear experienced by children during medical/nursing procedures.

Orientatractis bowseri n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of Peltocephalus dumerilianus (Schweigger) (Testudines: Podocnemididae) from the Brazilian Amazon.

Peltocephalus dumerilianus (Schweigger) is a diurnal freshwater turtle widely distributed in the Orinoco and Amazon River basins in Brazil, Colombia, Peru, Ecuador, Venezuela, and French Guiana. During a helminthological survey of freshwater turtles from the Brazilian Amazon, numerous nematodes with characteristics of the genus Orientatractis Petter, 1966 were recovered from the stomach of Peltocephalus dumerilianus. These nematodes were different from all congeneric species, and we describe herein. Orientatractis bowseri n. sp. differs from all known species of the genus by having dorsal cuticular projections on the posterior region of the females, distribution of caudal papillae and by having papilla-like ornamentations on the cuticle distributed from the mid-esophagus to the mid portion of the body. This study represents the fourth specie of the genus Orientatractis reported in Brazil, the seventh species of Orientatractis in the Neotropical region, and the third found infecting freshwater turtles in Brazil.

Effects of drought, invasive species, and habitat loss on future extinction risk of two species of imperiled freshwater turtle

While predicting species status into the future is inherently uncertain, it is necessary to properly inform conservation decision-making. Using a triple loop stochastic simulation model with a population viability analysis, we projected populations of the northwestern and southwestern pond turtle (Actinemys marmorata and Actinemys pallida, respectively) to the end of the century. We integrated the future trajectories and demographic or population-level effects of three primary threats (drought, invasive bullfrogs, and habitat loss) into the predictive model. Extinction risk of both species increased into the future, with projected widespread declines in abundance and a consistent, negative population growth. By the end of the century, mean probability of extinction was 50 % for the northwestern pond turtle and 75 % for the southwestern pond turtle. The northwestern pond turtle exhibited a latitudinal trend, with southern population units at greater risk of extinction. The population growth rate of the northwestern pond turtle was sensitive to the threat of invasive bullfrogs, whereas drought most strongly influenced southwestern pond turtle growth rates. Future drought conditions will likely be more stochastic than modeled here, where projection methods were limited by the scale and congruency of drought information in pond turtle studies. The habitat loss threat was negligible for both species, although it is likely underestimated due to lack of relevant information on both its future trajectory and effect on vital rates. This work served as decision support science for the Species Status Assessment of the two species, and ultimately, the listing decision under the U.S. Endangered Species Act.

Hyperpredation of Freshwater Turtles and Tortoises by Subsidized Corvids

Hyperpredation of Freshwater Turtles and Tortoises by Subsidized Corvids

Morphological and transcriptomic analyses of embryonic development of red-eared slider Trachemys scripta elegans

Embryology provides an understanding of individual’s origin and developmental patterns. Turtles are among the oldest living reptiles and have unique body structure. However, the morphogenesis and mechanisms of turtles are not fully understood. In this study, we focused on the embryonic development of red-eared slider (Trachemys scripta elegans) which widely distributes in the world. At an incubation temperature of 28 °C, the turtle eggs had a 61-day incubation cycle, and the entire embryonic development process was divided into 27 stages and 3 phases according to variations in age, body size, and morphological characteristics. The early phase of embryonic development (the first 12 stages) were characterized by embryo growth, and the appearance of internal organ precursors. The middle phase (stages 13–20) involved prominent heart division at stage 13 and the appearance of carapace and plastron at stages 14 and 17, respectively. In the later phase (stages 21–27), the hatchlings formed, and the carapace and plastron thickened. Transcriptome analysis of embryos showed enrichment of the differential genes in pathways related to development, metabolism, disease, and cellular processes. The Kyoto Encyclopedia of Genes and Genomes enrichment (KEGG) analysis implied the crucial regulatory role of the axon guidance pathway. Real-time fluorescence quantitative PCR indicated upregulated expression of wnt5a and bmp7 in stages 7 and 16 compared to that in stage 12. This study revealed the development process of red-eared slider embryo and the dynamics of the signaling pathway affecting its development, which supplemented the theory of embryo development, and provided new ideas for the molecular mechanism of turtle embryo development.

Effects of blood mercury accumulation on DNA methylation levels in the Khorat snail-eating turtle (Malayemys khoratensis)

Mercury (Hg) has adverse effects on humans and wildlife. Hg exposure can cause significant alterations in DNA methylation, an epigenetic modification that causes various illnesses. Hg accumulation in the blood of the Khorat snail-eating turtle (Malayemys khoratensis) from northeastern Thailand was previously reported. Thus, this study aimed to assess total mercury (THg) levels in M. khoratensis blood and to examine the impact of these concentrations on DNA methylation (5-methylcytosine, 5-mC) levels. We divided turtles based on morphological characteristics into two groups, normal and deformed, and then the levels of each variable in both groups were assessed. The deformed group presented higher mean THg concentration and DNA methylation levels compared to the normal group; however, the differences were not significant. Additionally, we found no correlation between DNA methylation levels and THg concentrations in both groups. This study is the first attempt to investigate the relationship between mercury accumulation and DNA methylation in the blood of deformed freshwater turtles.

Complete mitochondrial genome of the razor-backed musk turtle (Sternotherus carinatus, testudines: emydidae) in Korea

Sternotherus carinatus has been considered as a potential invasive species in Korea. However, the mitochondrial genome information of S. carinatus which can be used to control its effect on ecosystem is lacking. In this study, the complete mitochondrial genome of S. carinatus in Korea was sequenced and characterized. The mitochondrial genome consists of 37 genes (13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes) and a noncoding region. Phylogenetic analysis based on the mitochondrial genome sequences showed that S. carinatus from Korea is separated from other turtles which are the invasive species in Korea. Sequence divergence calculations indicated near-zero divergence between S. carinatus populations in Korea, the USA, and China, suggesting limited genetic differentiation. In the context of the broader issue of invasive species disrupting ecosystems, this research contributes to the identification of mitochondrial genomes for various freshwater turtle species, emphasizing the need for extended data collection to discern genetic mixing trends between native and non-native species. This study is a significant step toward managing S. carinatus as a potential invasive species in Korea.

The clinical features and treatment of fishhook injuries in freshwater turtles: 126 cases from 1997-2022.

To describe the clinical features, treatment, and outcomes of wild freshwater turtles with fishing hook injuries. 126 wild turtles residing in central North Carolina that were presented to a wildlife rescue clinic. Medical records from July 1997 to July 2022 were reviewed, and data were collected and analyzed. The most common species presenting for a fishhook injury was the yellow-bellied slider (Trachemys scripta scripta) (n = 69/126 [54.8%]; 95% CI, 45.7 to 63.6). The most common location identified was the oral cavity (n = 77/140 [55%]; 95% CI, 46.4 to 63.4) and the most common removal method was retrograde removal after cutting the barb off of the hook (76/120 [63.3%]; 95% CI, 54.1 to 71.9). Fishhooks embedded in the esophagus had a significantly higher chance of complications affecting recovery (OR estimate, 3.49; 95% CI, 1.07 to 11.38). There was no significant increase in mortality associated with the location of the injury; however, there was a significant increase in mortality in patients that experienced complications (P < 0.001). The time in care ranged from 1 to 150 days (median, 16 days). Of the turtles evaluated, 10.8% (n = 12/111; 95% CI, 5.7 to 18.1) were euthanized or died after treatment and 89.2% (99/111; 95% CI, 81.9 to 94.3) were released. These findings describe various successful techniques to remove fishhooks from turtles. While no superior treatment was identified, considerations should be taken to provide patient comfort, decrease injury-associated complications, and shorten recovery time by using minimally invasive techniques. Overall, freshwater turtles with fishhook injuries have a high release rate even when the injuries are severe.

Effects of cadmium on liver function in turtle Mauremys reevesii.

This research was designed to investigate the effects of cadmium (Cd) on liver function in turtle Mauremys reevesii. Turtles were divided into 4 groups at random. The turtles were injected intraperitoneally with Cd at 0, 7.5, 15, 30mgkg-1 Cd chloride separately. Liver index was calculated. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the content of TP in liver were examined with biochemical methods. The results indicated that the liver index of turtles changed obviously only at higher dose and longer time. The activities of ALT and AST in liver increased with prolongation of exposure time in a dose-dependent manner. TP content in liver was lower than that in the control. In summary, Cd had an obvious toxic effect on liver tissues of freshwater turtle Mauremys reevesii, and it was dose dependent with the extension of exposure time. But the results also showed that the turtle had strong tolerance to Cd.

Climate change affects the early‐life history of a freshwater turtle in a severely drying region

AbstractFreshwater turtles are one of the most threatened vertebrate groups. Climate change is a major threat to these species, with impacts affecting all life‐history stages. There is currently a limited understanding of how changes in climate may alter the environmental triggers for hatching and emergence from the nests of freshwater turtle hatchlings. This precludes making predictions about how climate change may impact freshwater turtle recruitment success. The southwestern snake‐necked turtle (Chelodina oblonga) is endemic to south‐western Australia, a global biodiversity hotspot that has undergone severe climatic drying. Recruitment failure is thought to be occurring in many populations of the species. However, there is little understanding as to how environmental change may be influencing recruitment. This study aimed to: (1) determine the incubation duration and hatching and hatchling emergence success of C. oblonga, (2) determine if the species exhibits hatching or emergence synchrony and/or delayed emergence and (3) quantify the effects of temperature and rainfall on hatchling emergence. Using this information, the study assesses how climatic drying and warming may be impacting C. oblonga's early life‐history. Between 2018 and 2020 nest sites were monitored around a large urban wetland with weekly assessments of egg and hatchling status. Incubation duration and hatching and hatchling emergence success were calculated, and generalized linear models were built to determine how temperature and/or rainfall predicted emergence. Hatchlings either emerged shortly after hatching or overwintered in the nest, and both hatching and emergence were asynchronous. Both emergence periods were positively associated with temperature and rainfall. This study reveals that incubation duration, hatching success, hatchling emergence and survival are all likely to be impacted by recent and projected climate change, and especially drying. Warming and drying are predicted for many temperate regions globally, and it is therefore important that their impacts on the early life history of freshwater turtles be better understood.

Tardigrades of North America: First Report of Water Bears on a Freshwater Turtle

Tardigrades of North America: First Report of Water Bears on a Freshwater Turtle

Effects of wetland connectivity on overwintering and movement behaviours of Australian freshwater turtles

AbstractFreshwater turtles are important consumers in Australian freshwater ecosystems. They serve as scavengers, nutrient regulators, and as food sources and Totems for Traditional Owners throughout Australia. Despite their importance, most Australian freshwater turtle species are declining. The impact of winter wetland drying on turtle populations remains unknown, and winter exposure of hibernating turtles may be an important additional source of mortality. We aimed to examine turtle responses to seasonal and episodic wetland drying in wetlands using acoustic telemetry and active trapping. Wetlands were chosen that spanned a range of hydrological connectivity to the adjacent Edward/Kolety‐Wakool River. We found that tagged Emydura macquarii typically exit wetlands disconnected from the adjacent permanent river prior to winter, and overwinter in the river. Female E. macquarii rapidly re‐entered ‘home’ wetlands (wetlands in which they were initially tagged) the following spring, whereas males tended to leave the study area, returning occasionally. Although we were not able to evaluate a winter drying event, one of the wetlands experienced partial summer drying. All three local turtle species (E. macquarii, Chelodina expansa, C. longicollis) exited the wetland long before winter drying would have become a potential threat. Our results suggest that turtles in this system may be protected from winter wetland drying because they move to the adjacent permanent river prior to winter. Spending the winter in the river channel reduces the risks of being trapped in a drying wetland as temperatures drop in winter.

Pesticide concentrations in a threatened freshwater turtle (Emys orbicularis): Seasonal and annual variation in the Camargue wetland, France

Wetlands are among the most threatened ecosystems on the planet and pollution is a major factor causing the decline of wetland biodiversity. Despite the increasing use of pesticides, their fate and effects on freshwater reptiles remain largely unknown. We studied the European pond turtle (Emys orbicularis), a long-lived species at risk with a high exposure potential to pesticides. Between 2018 and 2020, we measured 29 pesticides and metabolites in 408 blood samples of turtles from two populations in the Camargue wetland (France). We were able to quantify 24 compounds and at least one pesticide or one degradation product in 62.5% of samples. Pesticide occurrences and concentrations were low, except for a herbicide widely used in rice cultivation and locally detected in water: bentazone that reached high blood concentrations in E. orbicularis. The occurrence and the concentration of pesticides in E. orbicularis blood depended mainly on the site and the sampling date in relation to pesticide application. Individual characteristics (sex, age, body condition) did not explain the occurrence or the concentration of pesticides found in turtle blood. Assessing the exposure of aquatic wildlife to a cocktail of currently-used pesticides is a first and crucial step before studying their effects at the individual and population levels.