Podocnemis Unifilis Research Articles

Carcass yield, meat and fat color of yellow-spotted river turtles (Podocnemis unifilis) fed with Mauritia flexuosa fruit-based supplement

One way to increase the profitability of turtle farming is to provide even more differentiated products, for example, by adding value to the products and making them healthier for consumers. Moreover, M. flexuosa can be used as an alternative food for the incorporation of beneficial properties into products derived from animals that feed on this fruit. The present study aimed to evaluate the carcass yield, chemical composition, and meat and fat color of reproductive age yellow-spotted river turtle (Podocnemis unifilis) fed different levels of M. flexuosa fruit-based supplements for 30 and 50 days. Supplementation for a period of up to 50 days did not affect the carcass yield of the animals, and supplementation caused changes in the coloration patterns of the meat and fat of the animals after 30 days of supplementation.

Risk assessment for the consumption of the freshwater turtle Podocnemis unifilis with Hg in an indigenous population living close to mining area in the brazilian Amazon

Risk assessment for the consumption of the freshwater turtle Podocnemis unifilis with Hg in an indigenous population living close to mining area in the brazilian Amazon

Acanthoatractis xinguensis n. gen., n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of yellow-spotted Amazon river turtle, Podocnemis unifilis Troschel (Testudines: Podocnemididae) in Brazilian Amazon

Nematodes collected from the stomach of the yellow-spotted turtle Podocnemis unifilis Troschel, 1848 (Testudinidae) in the Brazilian state of Pará are assigned to a new genus, allocated to the family Atractidae (Cosmocerdoidea). Acanthoatractis n. gen. differs from all other genera of Atractidae based on the combination of the following morphological characters: cephalic extremity surrounded by eight bifurcated, wrench-shaped sclerotized structures arranged in a circle; oral opening encircled by two sclerotized pieces with pointed ends and a median portion with a pair of hooks; in males the larger (left) spicule is narrower in the middle third and the gubernaculum is absent. The type species, Acanthoatractis xinguensis n. gen., n. sp., has nine pairs of caudal papillae and a single papilla anterior to the cloacal lip. The new species is the seventh record of an atractid genus parasitizing P. unifilis.

Riverscape features determining the genetic structure of the Yellow‐Spotted Amazon River Turtle (Podocnemis unifilis) in Brazilian Amazonia

AbstractLandscape characteristics can influence gene flow depending on the species ability to disperse. This imposes different levels of resistance to movement, determining the genetic structure and diversity of populations. Waterfalls and rapids in the Amazon basin have been suggested as contributing factors to the diversification and genetic structure of freshwater species, including turtles. Thus, along some main rivers of the Brazilian Amazon: Juruá, Madeira, Amazonas, Trombetas, Tapajós, Xingu, Tocantins, and Araguaia, we evaluated the spatial distribution of genetic diversity and characterized the population structure of Podocnemis unifilis, a widely distributed and endangered Amazonian turtle, using the mitochondrial DNA control region. We tested for isolation by geographic distance and by resistance models through an integrative approach using genetic, geographic, and ecological data, comparing these matrices with genetic distance. We found heterogeneous levels of genetic diversity and no spatial patterns. Results supported the isolation by resistance hypothesis, where the movement of individuals was influenced by freshwater, vegetational, climatological, and geomorphological variables, explaining the genetic distance of P. unifilis. Rapids and waterfalls impose greater resistance although they are barriers with different levels of permeability to the P. unifilis gene flow. Thus, the idiosyncrasies of each sub‐basin must be considered in the interpretation of the patterns found in assessing phylogeographic history.Abstract in Portuguese is available with online material.

Insights into the shell microstructure of Bauruemys elegans and other pelomedusoids from the Cretaceous and Paleogene of Brazil, including first Testudines material from Jangada Roncador Village, Paraná Basin

Pelomedusoides and Chelidae are groups of pleurodiran turtles that have evolved from the Cretaceous period to the present. In this study, we carried out thin sections in shell elements (including costal, neural, peripheral and xiphiplastron bones) from Bauruemys elegans, an undetermined Podocnemididae taxon, and shell fragments of other pelomedusoids from Upper Cretaceous and Paleogene sedimentary deposits. We explored and discussed shell microstructures and microanatomy data of these extinct pelomedusoids alongside two extant pleurodires, Podocnemis unifilis and Phrynops sp. Our study of costo-neural bones reinforces the hypothesis that the turtle carapace originated endoskeletally from ribs and vertebral arches. Our osteohistological examination of these shell bones suggests an aquatic to semi-aquatic lifestyle for the studied extinct Pelomedusoides. Notably, all examined bones show high bone compactness, a feature often associated with terrestrial life, although it is not exclusive to such a lifestyle. Additionally, our comparative analysis reveals greater shell compactness in Podocnemididae compared to the other specimens sampled. These findings contribute to our understanding of the environmental interactions of these pleurodires.

Nesting trends and predation risks among yellow-spotted river turtles in Essequibo River Basin

The yellow-spotted river turtle (Podocnemis unifilis), inhabiting Amazon, Orinoco, and Essequibo River basins, is classified as vulnerable due to historical exploitation and current threats. Efforts have been made throughout the Amazon basin to understand the ecology of yellow-spotted river turtles and implement conservation measures, but the Essequibo River basin located in Guyana, remains the least studied part of the geographical range of the species. In this study we present data collected over a three-year period from 2020 to 2023, as part of a community driven conservation program by Yupukari village, in the North Rupununi, Guyana. We describe the nesting behavior of P. unifilis,and assess predation of eggs in the wild. A total number of nests in 9 beaches ranging from 59 (in 2021) to 76 (in 2023) (in averge 6.68 nest/beach, and 14.2 nests per ha) with an average number of 20.45 eggs per nest. Nesting locations were found to be predominantly situated within 1–20 m from the river, in proximity to vegetation, and on fine sand, with temperatures consistently falling within the 27–29 degrees Celsius range. Importantly, this study unravels the critical issue of nest predation, with lizards, human, and the birds emerging as the primary culprits, impacting nests located closer to vegetation to a greater extent. All nests in sites which potentially would be flooded were moved for a hatchery in the community of Yupukari in which the hatching success reached 83%.

Ninhos mais profundos aumentam a taxa de sobrevivência de embriões de tracajá no sul da região Amazônica

Abstract The reproductive ecology of a species is a key focus of conservation planning efforts as it offers insights into how the species persists and adapts to its environment. The Yellow-Spotted River Turtle, Podocnemis unifilis (Troschel,1848), has a wide distribution within the Amazon region and is generalist in its nesting site choice. Monitoring the nesting habits of this turtle is essential to understand the resilience of its populations and to evaluate the impact of environmental disruptions. This study aimed to assess how environmental factors affect the hatching rate, nest loss, and sex ratio of P. unifilis in the Iriri River, Pará. In 2012 and 2013, we monitored 121 nests over approximately 200km of the river within the Terra do Meio Protected Area. Nests with deeper egg chambers located at high elevated areas of the beaches had a higher mean hatching rate. Moreover, deeper nests had fewer rotten eggs and were less infected by Sarcophagidae fly larvae. Animals predated only two nests, and humans collected five nests. Nests that were manipulated presented lower hatching rates compared to unmanipulated nests. Furthermore, the sex ratio 100% biased towards females may indicate the limit of the behavioral and physiological plasticity of the species. Compared to other areas, P. unifilis nests had deeper egg chambers in the Iriri River, likely due to climate and nesting site granulometric profile. Our findings suggest that females of P. unifilis adjust nest characteristics to maximize the survival of their offspring in this coarse sediment environment. The plasticity in nesting site selection and nest depth highlights the species’ ability to adapt, enabling it to occupy a wide geographic area and successfully reproduce in various environments. However, climate change may gradually alter this situation, emphasizing the need to gather reproductive data from different sites to monitor the species’ capacity to adapt to habitat alterations.

ASSESSMENT OF A COMMUNITY MANAGEMENT PROGRAM OF RIVER TURTLES (PODOCNEMIDIDAE: Podocnemis) IN ZÁBALO, ECUADORIAN AMAZON

In Zábalo community within the Cuyabeno Fauna Production Reserve, a 26-year local initiative aimed at river turtle management was initiated following a significant decline in Podocnemis unifilis and P. expansa populations. Despite the program's lengthy history, weak monitoring and validation procedures prompted a comprehensive evaluation of management efficacy to strengthen the communitarian program. This assessment encompasses population estimates derived from nesting data (density, abundance, hatching success, hatchling production) for P. unifilis between 1994 and 2019. Some available data were also compiled for P. expansa which has not been the main focus of the communitarian program. Results highlight a positive temporal trend in P. unifilis population estimators, and a consistent high hatching success (81%), underscoring the program's contribution to the conservation of the species. Nonetheless, further research is imperative to assess age-specific population trends and enhance monitoring and management strategies for the relatively rare P. expansa.

A new species of Orientatractis (Nematoda: Cosmocercoidea: Atractidae) parasite of Yellow-Spotted Amazon River Turtle, Podocnemis unifilis Troschel, 1848 (Testudines: Podocnemididae) in Brazilian Amazon

The current study describes a new species of nematode, Orientatractis matosi n. sp. (Atractidae), from the stomach and large intestine of Podocnemis unifilis Troschel, 1848 (Testudinidae), collected in the Tocantins and Xingu rivers in the Brazilian state of Pará. The new species was described using light and scanning electron microscopy and differs from its congeners mainly in the number and distribution of the male caudal papillae and by having a shorter right spicule. Orientatracits matosi n. sp. is the eleventh species of the genus Orientatractis Petter, 1966, the third reported from the Amazon, and the second described from P. unifilis.

A NEW SPECIES OF PNEUMOATRACTIS (COSMOCERCOIDEA: ATRACTIDAE) FROM TWO SPECIES OF FRESHWATER TURTLES FROM THE BRAZILIAN AMAZON.

The monotypic genus PneumoatractisBursey, Reavill, and Greiner, 2009 was erected to allocate nematodes collected from the lungs of the freshwater turtle Podocnemis unifilis Troschel. During a helminthological survey of parasites from freshwater turtles of Tocantins and Xingu rivers, Pará State, eastern Amazon, Brazil, we found nematodes parasitizing the stomach and large intestine of Po. unifilis and Podocnemis expansa Schweigger. We assigned them to a new species of Pneumoatractis, which is described herein. Pneumoatractis gibbonsae n. sp. resembles Pneumoatractis podocnemis by the morphology of the oral opening, the position of the excretory pore, and the lanceolate shape of the spicules, but differs from it in males by having 10 pairs of caudal papillae plus 1 unpaired anterior to cloacal lip, different length of the right spicule, and short gubernaculum; it differs in females by the distances of vulva and anus from the posterior end respectively. We found the new species in a different infection site from that of the type species. Thus, this is the second species of Pneumoatractis described in Po. unifilis and the first in Po. expansa.

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.

Macrofauna parasitária de Podocnemis unifilis dos rios Tocantins e Javaés, Amazônia Oriental, Brasil

ABSTRACT: The parasitic fauna of Podocnemididae species is of great relevance to understanding the ecological relationships of the organisms in this genus. The parasites can have a symbiotic relationship with their hosts; however, environmental imbalances may change this relationship. Therefore, these parasites may become agents that generate zoonoses, especially in animals used by parasites as a food source. The aim of this study was to investigate the gastrointestinal parasitic fauna of specimens of Podocnemis unifilis. The animals were collected from the Tocantins and Javaés Rivers, both of which flow in the State of Tocantins, predominantly in the Cerrado territory. Samples of stomach and intestinal contents were fixed in 10% formalin buffered with sodium phosphate, transferred to 70% alcohol for analysis, and separated after 72 hours. Parasites were isolated and identified according to morphology and identification key. Four species of parasites were observed in 100% of specimens of P. unifilis, namely Nematophila grandis (Trematoda) and Paratractis hystrix, Paraorientatractis semiannulata, and Orientatractis leiperi (Nematoda). N. grandis was the only parasite that was not observed in the intestine; it appeared to adhere to the inner wall of the stomach. All nematodes were observed both in the stomach and intestine. These data expand the knowledge related to the P. unifilis parasitic fauna and the geographic distribution of these parasites in P. unifilis from the Tocantins and Javaés Rivers.

Aportes desde la ciencia ciudadana al Proyecto Tortugas de Bolivia en iNaturalist

We present an analysis of the contribution of citizen observers who are part of the Bolivian Turtle Project in the iNaturalist application created in 2019. We reviewed 213 observation records from 2000 to 2020, of which 194 correspond to 12 native species and 19 records are of introduced species. Of the total of records, 69% correspond to observations in the wild and 170 have been identified at species level, but only 118 are recognized as of research-value by iNaturalist, being the species with the best quality of information: Podocnemis unifilis, Chelonoidis denticulatus and Chelonoidis carbonarius. These three species and Phrynops geoffroanus are the most frequently observed. The work showed that the Bolivian Turtle Project is the most important at the national level for this taxonomic group and contributes to our knowledge of this group. It also reveals that there is a need to improve resources to improve observations and participation through the sharing of experiences and feedback with other resources on social media.

Molecular Evolutionary Relationships of Side-Necked Turtle Hemoglobin:cDNA-Derived Primary Structures and Computer-Assisted Tertiary Structuresof α<sup>A</sup>, α<sup>D</sup>, and β Globin Chains

Extant side-necked turtles consist of three families: Chelidae, Pelomedusidae, and Podocnemididae. The lasttwo families (the subject of this study) include five genera, three of which are endemic to Africa (Pelomedusa andPelusios) and Madagascar (Erymnochelys), while the other two (Podocnemis and Peltocephalus) are restrictedto South America. This study was undertaken to determine the molecular relationships of side-necked turtlesbased on the primary and tertiary structures of α^A, α^D, and β globin chains as deduced by cDNA sequencing and amachine-learning algorithm for protein structure prediction, AlphaFold2. Analyses of the globin primary structures of four species from different genera provide three major insights. (1) The genera Pelomedusa and Pelusiosmight be endemic taxa that diversified in Africa after the Gondwana separation. (2) Although the extant species ofErymnochelys and Podocnemis are restricted to Africa and South America, respectively, they are closely related toeach other, and thus, these genera apparently diversified during the breakup of Gondwana. Thus, the colonizationof the ancestral population of Podocnemis unifilis in South America might have coincided with continental drift.(3) The divergence times of the four species based on globin genealogy were estimated to have begun 120–11million years ago (mya), which generally coincides with the break-up of Gondwana 135–65 mya. In addition,tertiary structures predicted by AlphaFold2 were compared using a PyMOL overlaying technique. An in-depth examination of the four α^A globin chains revealed considerable consistency among species, and a similar pattern wasobserved for α^D and β globin chains. Additionally, species-specific differences were recognized among the primarystructures, and their higher-order structures (i.e., tertiary structures) were consistent, offering new information onthe molecular phylogeny of side-necked turtles.

Hematological and blood chemistry parameters of a Podocnemis vogli and P. unifilis captive population in Colombia.

The Podocnemididae family is seriously affected by anthropogenic factors, which is why almost all of their family members are threatened, according to the IUCN red list. The biology and ecology of these species, as well as the hematological and serum chemistry reference intervals that allow clinical action and decision-making conservation programs, are poorly known. Based on this, the objective of this study was to establish the hematological and blood chemistry parameters of the Savannah side-necked turtle (Podocnemis vogli) and Yellow-spotted river turtle (Podocnemis unifilis) maintained in captivity at the Estación de Biología Tropical Roberto Franco (Villavicencio-Colombia). Forty-nine captive turtles of the species P. vogli (n = 28) and P. unifilis (n = 21) were sampled to determine hematological and serum chemistry parameters. Blood samples were taken from the jugular veins of both male and female turtles across both species. Student's t-test and Mann–Whitney–Wilcoxon tests were used to compare values between the parameters evaluated against genders and sizes. Reference intervals were calculated for the hematological and biochemical values of each species. Some assessed parameters demonstrated significant differences between the males and females of both species. Most of the analyzed parameters exhibited similar reference intervals in both species. In this study, we report values and propose the hematological and serum chemistry reference intervals for P. vogli and P. unifilis, which can be used in the clinical diagnosis of these reptiles and in future research.

Mercury bioaccumulation, genotoxic and biochemical biomarkers reveal the health status of yellow-spotted Amazon River turtles (Podocnemis unifilis) in an environmental protection area in the Amazon

ABSTRACT Chelonians are considered good bioindicators of environmental quality. The assessment of the health status of chelonian populations in the Amazon is important because they are traditionally consumed in large numbers in riverine communities and sustainable use reserves. The present study aimed to evaluate the health of Podocnemis unifilis (Testudines, Podocnemididae) in an environmental protection area in the Amazon region in Brazil. We analyzed the biomarkers lipoperoxidation, carbonylation of proteins, occurrence of micronuclei and erythrocytic nuclear abnormalities, quantified metallothioneins, and evaluated mercury bioaccumulation. We generated pioneering data regarding biomarkers in wild Amazonian freshwater turtles. All biomarker responses did not vary significantly between the sexes. The occurrence of oxidative and genotoxic damage, as well as concentrations of metallothioneins was low compared to other studies. In addition, the bioaccumulation of mercury in the muscle of the animals was below the limit recommended for human consumption by the World Health Organization. Our results provide baseline data on mercury bioaccumulation and biomarker responses that can be useful for future comparisons with other freshwater turtles. The data also provide evidence that the sustainable exploitation of these turtles in the study area (Piagaçu-Purus Sustainable Development Reserve) does not pose a risk to local riverine communities, as the detected mercury concentrations are safe for human consumption. In this sense, our results highlight the importance of protected areas for the conservation of healthy turtle populations, at the same time ensuring the health of the human populations that use them as a food resource.

Heart morphology during the embryonic development of Podocnemis unifilis Trosquel 1948 (Testudines: Podocnemididae).

Cardiogenesis is similar in all vertebrates, but differences in the valvuloseptal morphogenesis among non-crocodilian reptiles, birds, and mammals are noted. The origin of mesenchymal structures such as valves that regulate the passage of blood and the formation of partial septa that prevent the complete mixing of oxygen-rich and low-oxygen blood present in adult chelonians are essential in the evolutionary understanding of complete septation, endothermy and malformations, even in mammals. In this context, this study analyzed the heart morphogenesis of Podocnemis unifilis (Testudines: Podocnemididae) from the 4th to the 60th day of incubation. We identified the tubular heart stage, folding of the cardiac tube and expansion of the atrial and ventricular compartments followed by atrial septation by the septum primum, ventricle septation by partial septa, outflow tract septation and the formation of bicuspid valves with cartilage differentiation at the base. The formation of the first atrial septum with the mesenchymal cap is noted during the development of the atrial septum, joining the atrioventricular cushion on the 17th day and completely dividing the atria. Small secondary perforations appeared in the mid-cranial part, observed up to the 45th day. Partial ventricle septation into the pulmonary, venous, and arterial subcompartments takes place by trabeculae carneae thickening and grouping on the 15th day. The outflow tract forms the aorticopulmonary and interaortic septa on the 16th day and the bicuspid valves, on the 20th day. Therefore, after the first 20 days, the heart exhibits a general anatomical conformation similar to that of adult turtles.

Patterns of wildlife hunting and trade by local communities in eastern Amazonian floodplains

Local people living in the Amazon rainforest rely heavily on wild meat as a source of protein and income. While the patterns and drivers of wildlife hunting and trade by local communities are well-known for upland forests, such aspects have been poorly explored in Amazonian floodplains. This study aims to describe wild meat hunting and trade patterns and assess the hunting dynamics of local communities in Amazonian floodplain areas. For this purpose, we interviewed 121 hunters in 36 communities living in white-water flooded forests in the lower Amazon River, Brazil. Thirty taxa were cited as hunted by interviewees, who used a repertoire of 13 hunting techniques. Aquatic and semi-aquatic taxa were the most prevalent, especially Hydrochoerus hydrochaeris, Cairina moschata, and Podocnemis unifilis. Eight taxa were cited as traded; wild meat was sold at 2.57 ± 2.22 USD/kg, while eggs of birds and turtles were sold at 0.37 ± 0.27 USD/unit. We found an inverted-U relationship between the body mass and the number of citations per taxa, with species weighing between 10-40 kg presenting the highest number of citations. The hunting patterns found here are different from those frequently found in the literature for upland environments. Understanding these hunting and trade patterns will help develop tailored wildlife conservation and management strategies for Amazonian floodplains.

RELATIONSHIP BETWEEN OVIPOSITION OF Podocnemis unifilis AND WATER LEVEL IN PERUVIAN AMAZONIAN FLOODPLAINS

In the Amazon floodplains, hydrological variability plays a crucial role by shaping the habitat, offering shelter and feeding or breeding areas. During the dry season, some fresh water turtles such as the yellow-spotted turtle (Podocnemis unifilis Troschel, 1848) use the sand banks at point bar areas as breeding sites, which must be available in time for the start of oviposition. In this study, we used altimetry-derived water level data from radar satellites combined with in-situ hydrological measurements to evaluate water level variations and relate them to oviposition starting dates (2003-2012) from Pacaya-Samiria National Reserve, Peru. Synchronous hydrological behavior was found between the major river stems (Ucayali and Marañon) and the inner rivers (Pacaya and Samiria), thus enabling the utilization of water level in the main river stem to correlate with oviposition in the inner rivers. Mean oviposition date was July 23nd with selection of a narrow water level range (92 masl ± 0.9 SD). Consistent shifts towards early/late oviposition were found for years with early/late dry season onset. Extreme biological shifts in terms of oviposition date onset, were identified for specific years (2004, 2010 and 2011) mainly for the extreme dry year of 2010.

Charapa Turtles (Podocnemis unifilis), an Opportunity to Improve Community Tourism and Contribute to Their Conservation in Yasuní National Park, Ecuador

Biodiversity at the species and ecosystem level is an important basis for tourism, especially for tourism economies in landscapes optimal for the conservation and sustainable use of biodiversity, which are addressed under the Convention on Biological Diversity. In the last two decades, the Podocnemis Unifilis turtle has presented problems represented in a decrease of individuals in their populations in the Ecuadorian Amazon. The objective of the study was to describe the characteristics and current situation of the charapa turtle (Podocnemis Unifilis), to analyze the perception of the community of the Indillama River towards this species and finally to establish a proposal for its conservation with a socio-economic contribution from the community tourism segment. The methodology used consisted of a bibliographic review, semi-structured interviews and expert judgment. The main results indicate that the charapa turtle has had population problems in the last 30 years due to various anthropogenic pressures. The inhabitants of the Río Indillama community perceive this species mainly as a source of economic income (sale of individuals and their eggs) and food by consuming their eggs and adult individuals. Finally, we present a proposal for conservation through tourism that provides experiential activities for the collection of P. unifilis eggs, nesting and release (sponsorship) of individuals, providing economic benefits to local communities. This will contribute to its conservation and local socioeconomic development.