Turtle Research Articles

Allometric-kinetic model predictions of radionuclide dynamics across turtle taxa

Chelonians (turtles, tortoises, and sea turtles; hereafter, turtles) inhabit a wide variety of ecosystems that are currently, or have the potential in the future to become, radioactively contaminated. Because they are long-lived, turtles may uniquely accumulate significant amounts of the radionuclides, especially those with long half-lives and are less environmentally mobile. Further, turtle shells are covered by scutes made of keratin. For many turtle taxa, each year, keratin grows sequentially creating annual growth rings or layers. Theoretically, analysis of these scute layers for radionuclides could provide a history of the radioactivity levels in the environment, yet there are few previously published studies focused on the dynamics of radionuclide intake in turtles. Using established biochemical and ecological principles, we developed an allometric-kinetic model to establish relationships between the radionuclide concentrations in turtles and the environment they inhabit. Specifically, we calculated Concentration Ratios (CRs – ratio of radionuclide concentration in the turtle divided by the concentration in the soil, sediment, or water) for long-lived radionuclides of uranium and plutonium for freshwater turtles, tortoises, and sea turtles. These CRs allowed prediction of environmental concentrations based on measured concentrations within turtles or vice-versa. We validated model-calculated CR values through comparison with published CR values for representative organisms, and the uncertainty in each of the model parameters was propagated through the CR calculation using Monte Carlo techniques. Results show an accuracy within a factor of three for most CR comparisons though the difference for plutonium was larger with a CR ratio of about 200 times for sea turtles, driven largely by the uncertainty of the solubility of plutonium in sea water.

Assessing translocation success and long‐distance homing in riverine turtles 10 years after a freshwater oil spill

AbstractWildlife translocation is often used as a mitigation strategy for construction projects and other disturbances to habitat. In 2010, one of the largest freshwater oil spills in the United States occurred in the Kalamazoo River in Michigan, when over 3.2 million L of diluted bitumen crude oil impacted nearly 56 km of riverine habitat. During 2010 and 2011 cleanup efforts, 686 northern map turtles (Graptemys geographica) were captured from oil‐impacted stretches of the river, cleaned, rehabilitated, and translocated 2.5–84.3 km from their original capture location. The goal of this translocation effort was to release turtles within the same watershed, but away from ongoing cleanup operations, so individuals could potentially return to their original home range after it had been cleaned of oil and restored. In this study, we evaluated the success of translocation as an emergency mitigation strategy for freshwater turtles by quantifying recapture probability and homing by northern map turtles translocated varying distances from their home ranges. During subsequent years of survey up to 10 years post‐spill, 230 of the translocated turtles were recaptured, of which 104 exhibited homing by returning to their original home ranges. Turtles translocated to sites nearest their original capture location had a higher probability of recapture and homing than those translocated further away. Females had a higher probability of returning to original home ranges than males when translocated greater distances. In addition, four females and one male are known to have traveled >50 km between capture and release locations, which to our knowledge is the greatest travel distance recorded for any freshwater turtle species in the United States. Our results demonstrate that riverine turtles have considerable homing ability when displaced long distances, which has important implications for design and success of translocation projects.

Integrating eDNA and citizen science observations to model distribution of a temperate freshwater turtle near its northern range limit.

To determine species distributions and the factors underlying them, reliable occurrence data are crucial. Assembling such data can be challenging for species with cryptic life histories or that occur at low densities. We developed species-specific eDNA protocols, from sampling through data interpretation, to detect the common musk turtle (Sternotherus odoratus) and tested whether eDNA occurrences change our understanding of the species distribution and the factors that shape its northern range limit. We used Species Distribution Models (SDMs) with full parameter optimization on citizen science observations of S. odoratus in Southern Ontario alone and together with eDNA occurrences. Our eDNA protocol was robust and sensitive. SDMs built from traditional observations and those supplemented with eDNA detections were comparable in prediction accuracy. However, models with eDNA detections suggested that the distribution of S. odoratus in Southern Ontario is underestimated, especially near its northern range limit, and that it is shaped by thermal conditions, hydrology, and elevation. Our study underscores the promise of eDNA for surveying cryptic aquatic organisms in undocumented areas, and how such insights can help us to improve our understanding of species distributions.

Towards a Diagnostic Tool for Turtle Ootaxonomy: Investigation of Microstructural Differences in the Eggshells of Australian Freshwater Turtles

Researchers frequently encounter turtle nests after the nest has been raided, finding only eggshell fragments that are difficult to identify. Valuable information on the breeding biology and needs of different species might still be collected from these nests if remains could be confidently assigned to a particular species. However, this can be difficult if there are multiple turtle species nesting within an area at a given time, and gross-scale characteristics such as egg size and shape are no longer available due to damage. This study examined eggshell microstructure, by scanning electron microscopy (SEM), among multiple species of freshwater turtle eggshell fragments, with the aim of potentially developing a diagnostic tool for species identification. Eggshell fragments were collected from known sources of four species of turtle native to eastern Australia: Eastern Long-necked Turtle (Chelodina longicollis), Murray River Turtle (Emydura macquarii), Bell's Turtle (Myuchelys bellii), and Bellinger River Turtle (M. georgesi). Fragments were scanned and analyzed for microstructural and ultrastructural features, and measured for differences in feature size across species. Central plaque diameter emerged as a potential diagnostic feature for separating species, with longneck turtle eggshells having no visible plaques, Murray River Turtle eggshells having relatively small mean plaque size (19.8 µm ± 10.28 SD), while Bell's Turtle (43.5 µm ± 14.16 SD) and Bellinger River Turtle eggshells (41.9 µm ± 15.41 SD) had relatively large plaques with little overlap between genera. Other measured features (shell unit size, basal knob size, and shell unit density) significantly differed in means among species but overlapped in range, or showed a lack of statistical difference, likely preventing the technique being definitive with a single measure. Some of this variance may be due to inherent confounding factors, such as the replicability of fragment preparation, condition of eggshells, and stage of embryonic development at the time of collection. These results suggest that use of measurements of microstructural features has promise as a means for distinguishing the provenance of eggshell fragments, and further investigation is warranted to develop site-specific protocols for use as a diagnostic tool for turtle ootaxonomy.

Helminths of freshwater turtles in Northeastern Brazil: parasite–host–environment relationships

ABSTRACT The parasitic fauna of reptiles is considered understudied compared to that of other vertebrates and is even less well known than the parasitic fauna of chelonians. Yet parasites are considered one of the main controllers of host populations because they can strongly impact population structure and species diversity. The objective of the present study was to identify the helminth fauna infecting freshwater turtles Phrynops geoffroanus and Mesoclemmys tuberculata, to evaluate the effects of host features (body mass and sex) and seasonality (dry and rainy seasons) on the abundance of parasites, and to compare infection rates in each host species between different biomes (Caatinga and Atlantic Forest) in an area of Northeastern Brazil. We found seven species of helminths that belong to Nematoda (Physaloptera sp., Serpinema amazonicus, Serpinema monospiculatus and Spiroxys figueiredoi), Cestoda (unidentified specimen), Digenea (Echinostomatidae) and Monogenea (Polystomoides brasiliensis). For both freshwater turtle species, we did not find a significant difference in the abundance of helminths related to the maximum carapace length, body mass or host sex; however, males had higher prevalence than females, while females presented greater abundance when infected. We observed significant differences in the infection levels between biomes and between seasons (dry and rainy), where the Atlantic Forest specimens showed higher infection rates compared to the Caatinga and the highest rates occurred in the dry season. The main parasitological parameters observed in P. geoffroanus and M. tuberculata showed that the studied biomes directly influenced the levels of parasitic infection. Variations in habitat characteristics can directly influence patterns of helminth diversity and abundance, and interactions between these characteristics can generate differences in parasitism rates of the same host species in different environments.

Sex-specific innate immunity and ageing in long-lived fresh water turtles (Kinosternon flavescens: Kinosternidae)

BackgroundThe progressive deregulation of the immune system with age, termed immunosenescence, has been well studied in mammalian systems, but studies of immune function in long-lived, wild, non-mammalian populations are scarce. In this study we leverage a 38-year mark-recapture study to quantify the relationships among age, sex, survival, reproductive output and the innate immune system in a long-lived reptile, yellow mud turtles (Kinosternon flavescens; Testudines; Kinosternidae).MethodsWe estimated rates of survival and age-specific mortality by sex based on mark-recapture data for 1530 adult females and 860 adult males over 38 years of captures. We analyzed bactericidal competence (BC), and two immune responses to foreign red blood cells - natural antibody-mediated haemagglutination (NAbs), and complement-mediated haemolysis ability (Lys) - in 200 adults (102 females; 98 males) that ranged from 7 to 58 years of age captured in May 2018 during their emergence from brumation, and for which reproductive output and long-term mark-recapture data were available.ResultsWe found that females are smaller and live longer than males in this population, but the rate of accelerating mortality across adulthood is the same for both sexes. In contrast, males exhibited higher innate immunity than females for all three immune variables we measured. All immune responses also varied inversely with age, indicating immunosenescence. For females that reproduced in the preceding reproductive season, egg mass (and therefore total clutch mass) increased with age,. In addition to immunosenescence of bactericidal competence, females that produced smaller clutches also had lower bactericidal competence.ConclusionsContrary to the general vertebrate pattern of lower immune responses in males than females (possibly reflecting the suppressive effects of androgens), we found higher levels of all three immune variables in males. In addition, contrary to previous work that found no evidence of immunosenescence in painted turtles or red-eared slider turtles, we found a decrease in bactericidal competence, lysis ability, and natural antibodies with age in yellow mud turtles.

Evaluation of headstarting as a conservation tool to recover Blanding's Turtles (Emydoidea blandingii) in a highly fragmented urban landscape.

Freshwater turtle populations are declining globally as a result of anthropogenic activities. Threats to turtles in urban areas are exacerbated by road mortality and subsidized predators, which can lead to catastrophic shifts in population size and structure. Headstarting is used as a conservation tool to supplement turtle populations that may otherwise face extirpation. A headstarting program began in 2012 to recover a functionally extinct population of Blanding's Turtles (Emydoidea blandingii) 26in Rouge National Urban Park (RNUP), Ontario, Canada. The original population included five adults and one juvenile turtle. From 2014 to 2020, 270 headstarted turtles were released. The population has been monitored annually since 2014 using visual-encounter surveys, radio-telemetry, and live trapping (from 2018 onwards). We used mark-recapture and radio-telemetry data to quantify abundance, survival, and sex ratio of the headstarted turtle population. Using a Jolly-Seber model, we estimated abundance to be 183 turtles (20 turtles/ha) in 2020. Estimated survival of headstarted turtles approached 89%, except for turtles released in 2019 when survival was 43% as a result of a known mass mortality event at the study site. Pre- and post-release sex ratios were not significantly different (χ2 = 1.92; p = 0.16), but shifted from 1:1.5 to 1:1 male:female post-release. Given that the headstarted turtles have not yet reached sexual maturity, it is unclear whether headstarted turtles will reach adulthood and successfully reproduce to maintain a self-sustaining population. Thus, to evaluate the success of the headstarting program, long-term monitoring is required.

Evaluation of metal exposure through the composition of essential and toxic micro-minerals in freshwater turtles (Phrynops geoffroanus) from a Brazilian river

This study aimed to evaluate metal exposure through the concentration of essential and toxic micro-minerals in biological samples of Phrynops geoffroanus from an anthropized river. The work was carried out in four areas with different flow characteristics and uses of the river, where individuals of both sexes were captured during the dry and rainy seasons. The elements Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, and Zn were quantified in samples of serum (168), muscle (62), liver (61), and kidney (61) by inductively coupled plasma optical emission spectrometry. The concentration of the elements varied according to the sample type, being higher in the liver and the kidney. In the serum, many elements were below the limit of quantification, but it was possible to determine Al, Cu, Fe, Mn, Pb, and Zn. The liver showed high levels of Cu, Fe, Pb, and Zn, and muscle for Fe, Ni, Pb, and Zn, with most of the elements accumulated in the kidney (Al, Cd, Co, Cr, Mn, Mo, and Ni) relative to other tissues. There was no significant difference between the sexes in the accumulation of elements. Between seasons, Cu was higher in serum and Mn in muscle and liver in the dry period, while in the kidney, almost all the elements were higher in the rainy period. The concentrations of the elements in the samples indicated a high degree of environmental contamination, representing risk in the use of the river and consumption of food from local fisheries.

Prevalence of Haemogregarina stepanowi and Assessment of Some Risk Factors in Mauremys rivulata (Valenciennes, 1833) Freshwater Turtles (Testudines: Geoemydidae)

The Balkan terrapin, Mauremys rivulata, is a freshwater turtle. This reptile is exposed to many environmental pollutants and some infectious agents, including Haemogregarina stepanowi parasite. This study was conducted to determine the microscopic prevalence of haemogregarine infection in M. rivulata caught in three different localities (Bozcaada, Gökçeada, and Dardanos) in Çanakkale province of Turkey, and assessment of some risk factors. Twenty-four blood samples were collected, thin blood smears were prepared, and the presence of haemogregarine parasites microscopically was screened. Water samples were also taken from the habitats, and these samples were analyzed physiochemically and microbiologically. Morphological identification was made by detecting the sausage-shaped intra-cytoplasmic developmental stages of H. stepanowi, and thirteen of twenty-four turtles (54.2%) were found to be infected. The prevalence of H. stepanowi was detected as the highest (90.0%) in the Gökçeada district, where the water pollution is higher than in the other localities. A statistically significant relationship was observed between the distribution of the infection and the gender of the turtles, the temperature of the water, the number of faecal coliforms in water and the amount of dissolved oxygen in the water. A statistically significant difference was found between the localities in terms of the prevalence of H. stepanowi infection, and the infection was primarily detected in the Gökçeada district. This study has significance in providing information regarding haemoparasitic diseases of freshwater turtle, M. rivulata, in Turkey.

Nocturnal emergence facilitated by thermally-induced hatching in the Chinese softshell turtle, Pelodiscus sinensis.

The coincidence of hatching and emergence events with favorable conditions is crucial for turtle survival. Nocturnal emergence has been widely documented across marine and freshwater turtles, and has long been suggested as an adaptive behavior that reduces risks of heat stress and predation. To our knowledge, however, studies related to nocturnal emergence have mainly focused on the post-hatching behaviors of turtles, and very few experimental studies have been performed to investigate the effects of hatching time on the distribution of emergence times over the course of a day. Here, we visually monitored the activity of the Chinese softshell turtle (Pelodiscus sinensis)-a shallow-nesting freshwater turtle-from hatching to emergence. Our study provides evidence for the novel finding that (i) the timing of synchronous hatching events in P.sinensis coincides with the time of day when nest temperatures decrease, (ii) the synchrony between hatching and emergence may further facilitate their nocturnal emergence, and (iii) synchronous behaviors of hatchlings in the nest may be effective in reducing the risk of hatchling predation, and predation is more likely to occur in the asynchronous hatching groups. This study suggests that the hatching of shallow-nesting P.sinensis in response to temperature changes in the nest might be an adaptive nocturnal emergence strategy.

The First Next-Generation Sequencing Metabarcoding Dataset on Faecal Bacterial Diversity from the Southern River Terrapin, Batagur affinis ssp.

The Southern River terrapin, Batagur affinis ssp., has the first data on faecal bacterial diversity from next-generation sequencing (NGS). This dataset describes the bacterial diversity of the Southern River terrapin, locally known as Tuntung. Batagur affinis spp. are freshwater turtles listed as critically endangered on the International Union for Conservation of Nature (IUCN) Red List since 2000. This is the first dataset on the faecal bacterial diversity of Batagur affinis ssp., and the data provided here can be used to comprehensively understand the microbiome's community composition. Seven faeces samples were collected aseptically from captive (N = 5) and wild (N = 2) adult B. affinis ssp. while crossing Peninsular Malaysia's east and west coasts. The data was acquired by metabarcoding using 16S rRNA. The amplicons were further analysed using the SILVA and DADA2 pipelines. The V3-V4 of the 16S rRNA gene region was amplified, and the amplicons were sequenced on the Illumina MiSeq system. In total, 297 bacterial communities' taxonomic profiles (phylum to genus) have been determined. The data for this metagenome can be found in the BioSample Submission Portal as Bio-Project PRJNA767629 and Sequence Read Archive (SRA) accession numbers from SAMN21919713 to SAMN21919722.

Diversity of Underwater Vocalizations in Chinese Soft-Shelled Turtle (Pelodiscus sinensis).

Sound communication is important for underwater species. The wild population of the Chinese soft-shelled turtle (Pelodiscus sinensis) is listed as vulnerable. However, its vocalization, which can serve as the basis for ecological and evolutionary research, has not been studied. Here, we performed underwater recordings of 23 Chinese soft-shelled turtles of different ages and sexes and identified 720 underwater calls. The turtle calls were manually divided into 10 call types according to visual and aural inspection properties. The similarity test indicated that the manual division was reliable. We described the acoustic properties of the calls and the statistical analysis showed that the peak frequency of calls was significantly different between adult females and males, and also between subadults and adults. Similar to other aquatic turtles that prefer to live in deep water, Chinese soft-shelled turtles have a high vocal diversity and many harmonic calls, indicating that this highly aquatic species developed a variety of vocalizations to enhance their underwater communication, which helped them adapt to the complex and dim underwater environment. Furthermore, the turtles showed a tendency for vocalization to become more diverse with age.

Hemogregarine Diversity Infecting Brazilian Turtles with a Description of Six New Species of Haemogregarina (Apicomplexa: Adeleorina: Haemogregarinidae)

(1) Background: Hemoparasites of the genus Haemogregarina (Haemogregarinidae) are commonly reported in freshwater turtles. However, in Brazil, only three species have currently been characterised using molecular methods. This study aimed to bring new insights on the diversity of species of Haemogregarina infecting Brazilian freshwater turtles from Mato Grosso and Goiás states using molecular and morphological tools. (2) Methods: In total, 2 mL of blood was collected, with between two to five blood smears prepared, fixed with absolute methanol, and stained with a 10% Giemsa solution. Blood was stored at −20 °C for molecular analysis targeting the 18S rRNA gene. Fragments of the organs (liver, spleen, heart, and kidney) were separated and stained with hematoxylin-eosin. (3) Results: A total of 40 turtles were screened and hemogregarines were observed in 34 (85%) individuals (3 Podocnemis expansa and 31 Podocnemis unifilis). Haemogregarina embaubali and six new species of Haemogregarina were observed and formally described as follows: H. unifila n. sp., H. rubra n. sp., H. goianensis n. sp., H. araguaiensis n. sp., H. tigrina n. sp., and H. brasiliana n. sp. (4) Conclusions: This study contributes to the diversity and knowledge of Brazilian fresh-water turtle blood parasites, using integrative approaches for diagnosing and characterizing hemoparasites, with the identification of six undescribed species.

Confirmation of the local establishment of alien invasive turtle, Pseudemys peninsularis, in South Korea, using eggshell DNA.

Alien invasive species are posing conservation challenges worldwide. Pet trade, one of the many ways, is worsening the situation. Especially, pet turtles have been released into nature due to their longer life span and peoples' religious and traditional beliefs. In addition, unwanted and undesired pets are also released. While information on the successful local establishment and subsequent dispersal into new habitats is required to designate an invasive and ecosystem-disturbing species, alien freshwater turtle nests have always been hard to find and identify in nature. Because one should identify nests by the eggs, which do not always guide properly, as adults abandon the sites quickly. We thought the recent advancement in DNA technology may help improve the situation. We studied Pseudemys peninsularis, one of the most traded freshwater turtle pet species, which has already been reported from a wide range of wild areas in South Korea. Yet, it is not designated as ecosystem-disturbing species due to a lack of adequate information on their local reproduction and establishment. We conducted surveys and found two nests in Jeonpyeongje Neighborhood Park, Maewol-dong, Seo-gu, Gwangju. We developed the methodology for extracting DNA from the eggshells and successfully identified the nests by phylogenetic analysis and verified through egg characteristics and morphological features of artificially hatched juveniles. This was the first successful initiative to extract DNA from freshwater turtle eggshells. We believe it will help future researchers identify the alien invasive turtle nests and develop their control and management policies. In addition, our study also included comparative descriptions and schematic diagrams of the eggs of eight freshwater turtles, including a native and three ecosystem-disturbing species, from South Korea. We urged an immediate designation of P. peninsularis as an ecosystem-disturbing species considering its local establishment, distribution range, and potential negative impact on native ecosystems.

Minor metabolomic disturbances induced by glyphosate-isopropylammonium exposure at environmentally relevant concentrations in an aquatic turtle, Pelodiscus sinensis

The ecotoxicological and environmental impacts of glyphosate-based herbicides have received considerable attention due to their extensive use globally. However, the potential for adverse effects in cultured non-fish vertebrate species are commonly ignored. In this study, effects on growth, indicators of functional performance, gut microbial diversity, liver antioxidant responses and metabolite profiles were evaluated in soft-shelled turtle hatchlings (Pelodiscus sinensis) exposed to different concentrations of glyphosate-isopropylammonium (0, 0.02, 0.2, 2 and 20 mg/L). No significant changes in growth or functional performance (food intake, swimming speed), gut microbiota, and liver antioxidant responses (SOD and CAT activities, MDA content) were observed in exposed turtles. However, hepatic metabolite profiles revealed distinct perturbations that primarily involved amino acid metabolism in turtles exposed to environmentally relevant concentrations. Overall, our results suggested that metabolite profiles may be more sensitive than phenotypic or general physiological endpoints and gut microbiota profiling, and indicate a potential mechanism of hepatotoxicity caused by glyphosate-isopropylammonium based on untargeted metabolomics analysis. Furthermore, the toxicity of glyphosate at environmentally relevant concentrations might be relatively minor in aquatic turtle species.

Piscichuvirus-Associated Severe Meningoencephalomyelitis in Aquatic Turtles, United States, 2009-2021.

Viruses from a new species of piscichuvirus were strongly associated with severe lymphocytic meningoencephalomyelitis in several free-ranging aquatic turtles from 3 coastal US states during 2009-2021. Sequencing identified 2 variants (freshwater turtle neural virus 1 [FTuNV1] and sea turtle neural virus 1 [STuNV1]) of the new piscichuvirus species in 3 turtles of 3 species. In situ hybridization localized viral mRNA to the inflamed region of the central nervous system in all 3 sequenced isolates and in 2 of 3 additional nonsequenced isolates. All 3 sequenced isolates phylogenetically clustered with other vertebrate chuvirids within the genus Piscichuvirus. FTuNV1 and STuNV1 shared ≈92% pairwise amino acid identity of the large protein, which narrowly places them within the same novel species. The in situ association of the piscichuviruses in 5 of 6 turtles (representing 3 genera) with lymphocytic meningoencephalomyelitis suggests that piscichuviruses are a likely cause of lymphocytic meningoencephalomyelitis in freshwater and marine turtles.

Media portrayal of the illegal trade in wildlife: The case of turtles in the US and implications for conservation

AbstractIllegal wildlife trade is a global threat to biodiversity, but its drivers and impacts and ways to combat it vary by taxa. News media framing of instances of illegal trade provides a novel window into understanding public perceptions of these dynamics and potential support for management actions.We used 54 known cases of illegal turtle trade in the United States occurring between 1998 and 2021 as a case study to investigate news media framing of this emergent issue in illegal wildlife trade. We synthesized information from these cases and qualitatively analysed how they were framed in 217 associated news articles.The 54 cases involved the illegal trade of at least 24,000 freshwater turtles of 34 different species; box turtles (Terrapenespp.) were traded the most. Of the known species involved, 23 were listed under one of the CITES Appendices, and 12 were considered threatened by the International Union for the Conservation of Nature. Trade occurred in at least 43 US states and 6 countries.Despite the multifaceted nature of these cases, problem and solution framing were relatively unvarying. Media coverage framed foreign demand, particularly from Asia for high‐value pet turtles, as a main driver of illegal trade. Solutions focused on regulations and enforcement which follows global trends in illegal wildlife trade discourses. However, we also found that articles neutralized illegal turtle trade in several ways, reflecting a lack of perceived legitimacy of and necessity for trade rules and enforcement.Without acknowledging longstanding and formerly legal practices in wildlife trading, conservation efforts which focus on regulations and enforcement may be undermined by a lack of normative compliance.Read the freePlain Language Summaryfor this article on the Journal blog.

Consequences of Heatwave on Density of Freshwater Turtle Populations in Water Plans of Northeastern Algeria

Aquatic turtles are ectotherm animals whose activities are conditioned by their environment. The objective of this study is to asses the heatwave effects on the abundance of aquatic turtles. The resulting study was conducted from spring to fall 2022, in a water plan next to Guerbes Sanhadja wetlands eco complex, known for the density of aquatic turtles it hosts. Temperature and rainfall data, as well as satellite images and field photography, were utilised to monitor the drying of the water plain. . Freshwater turtles were counted remotely every one hour from a specific location. The results obtained confirm the resumption of aquatic turtle activity, particularly marked in summer, but the persistence of heatwave, with abnormally high air temperatures and very low rainfall, caused the gradual drying up of the water plan and a sharp drop in turtle’s numbers.

Chinese striped-neck turtles vocalize underwater and show differences in peak frequency among different age and sex groups.

Turtle vocalizations play an important role throughout their lives by expressing individual information (position, emotion, or physiological status), reflecting mating preferences, and synchronizing incubation. The Chinese striped-neck turtle (Mauremys sinensis) is one of the most widely distributed freshwater turtles in China, whose wild population is critically endangered. However, its vocalization has not been studied, which can be the basis for behavioral and ecological studies. Five different sex-age groups of turtles were recorded underwater in a soundproof room. Cluster analysis and principal component analysis for classification of Chinese striped-neck turtle calls were unreasonable. The turtle calls were manually sought using visual and aural inspection of the recordings in Raven Pro 1.5 software and classified according to differences perceived through auditory inspection and the morphological characteristics of the spectrograms. The results of similarity analysis verified the reliability of manual classification. We compared the peak frequency of the calls among different age and sex groups. We identified ten M. sinensis call types, displayed their spectra and waveforms, and described their auditory characteristics. Most calls produced by the turtles were low-frequency. Some high-frequency call types, that are common in other turtle species were also produced. Similar to other turtles, the Chinese striped-neck turtle generates harmonic vocalizations. Courtship behaviors were observed when one of the call types occurred in the mixed-sex group. Adult females produced more high-frequency call types, and subadult males had higher vocalizations than other groups. These results provide a basis for future research on the function of vocalizations, field monitoring, and conservation of this species.

External Morphological Description of Adult Tortoise (Testudo graeca graeca) and Terrapin (Trachemys scripta elegans)

Our study was focused on the external features differentiation of two adult species of turtles, including a land tortoise (Testudo graeca graeca) and a freshwater turtle (Trachemys scripta elegans), by gross morphological description of head, carapace, plastron, and tail. Generally, turtles show gross morphological differences according to the ecology and the environment. The carapace and legs are the fascinating noticeable parts showing significant differences between tortoise and turtle as T. graeca graeca shows a small carapace length with noticeable convexity. In contrast, the freshwater turtle has a flattened broad carapace adapted to swimming. At the same time, the legs of T. graeca show multiple keratinized spurs with rigid claws, but T. scripta has legs covered with soft, moist skin and thin claws. The plastron is relatively the same in both species, while the head is unique with a large size and red flap in T. scripta. We conclude that the flat body and legs with broad head are a modification for swimming, while the rigid claws with keratinized outer leg skin are signs of land walking adaptation.