River Turtle Research Articles

The role of receptivity in the courtship behavior of Podocnemis erythrocephala in captivity.

The courtship behavior of Podocnemis erythrocephala (Red-headed Amazon River Turtle) in captivity was studied to examine female receptivity and male response to female rejection. We observed 20 females and 39 males in 150 sessions (3–6 h/day for a total of 450 h). In 36% of the trials, there was no interaction between males and females, and 20% of the trials resulted in copulations. All males introduced into tanks approached females, and eventually there was aggression among the males. In 48% of the experiments, females also searched for or approached males. When males initially approached females, they either accepted the male’s advances (14%), rejected the male passively (38%), or rejected the male aggressively (48%). In 86% of the cases where males were rejected, 4% attempted to approach females again, and in 51% they were ultimately successful.

Ontogeny of the Plastron of the Giant Amazon River Turtle,Podocnemis expanse(Schweigger, 1812) (Testudines, Podocnemididae)

Podocnemis expanse, known popularly as the giant Amazon river turtle, is widely exploited. This makes specimens available for various studies, and we used this opportunity to investigate aspects of the development of the plastron. We examined several stages of pre- and post- hatching development in embryos and hatchlings collected starting from day 18 of natural incubation. Embryos and hatchlings were cleared and double stained for cartilage and bone. The epiplastron, endoplastron, hyoplastron, hypoplastron, xiphiplastron, and mesoplastron bones form the complete plastron of this turtle. In stage 16, bone centers become visible in most of the bones of the plastron. Alizarin Red stain retention indicated that the sequence of bone ossification is as follows: first the hyoplastron and the hypoplastron, then the endoplastron followed by the xiphiplastron, and lastly the mesoplastron. The epiplastron bone shows an ossification center only in stage 20. All these elements have independent ossification centers and join together only later. The plastron closes completely seven months after hatching.

Pneumoatractis podocnemis n. gen., n. sp. (Nematoda: Atractidae) from the Yellow-Spotted Amazon River Turtle, Podocnemis unifilis (Testudines: Pelomedusidae)

Nematodes collected at postmortem examination from the lungs of a yellow-spotted Amazon River turtle, Podocnemis unifilis, are described and assigned to a new genus, Pneumoatractis, the twenty-first genus of the superfamily Cosmocercoidea, family Atractidae. The new genus is most similar to congeners possessing a noncosmocercid esophagus and lacking anterior cuticularized formations, namely, Atractis, Cyrtosomum, Leiperenia, Monhysterides, Paratractis, and Rondonia. The new genus differs from the above congeners as follows: males of Atractis have 1 lagenoid spicule and 1 lanceolate spicule, males of Pneumoatractis possess 2 lanceolate spicules; males of Cyrtosomum lack a gubernaculum, a gubernaculum is present in Pneumoatractis; in Leiperenia the anterior part of the esophagus is one fourth of total length of esophagus, in Pneumoatractis the anterior part is one half of total length; Monhysterides lacks lips, which are well developed in Pneumoatractis; Paratractis has scale-like cuticular projections along the dorsal surface of the body in contrast to the smooth surface of Pneumoatractis; and females of Rondonia possess a cloaca, females of Pneumoatractis have separate openings for digestive and reproductive tracts. The new genus also differs from other genera of the family in that it was found in the lungs rather than the intestines.

Influence of the Hydric Environment on Water Exchange and Hatchlings of Rigid‐Shelled Turtle Eggs

To examine the possible influence of incubation substrate water potential on rigid-shelled chelonian eggs and hatchlings, rigid-shelled eggs from four clutches of Brisbane River turtle (Emydura signata) were incubated buried in vermiculite at water potentials of approximately -100, -350, and -850 kPa, and patterns of egg mass change and hatchling attributes were examined. All eggs hatched successfully, and there was no apparent effect of water potential on incubation period, fresh hatchling mass, hatchling water content, or hatchling size. Clutch of origin also had no apparent effect on these attributes when initial egg mass was used as a covariate. However, clutch of origin affected initial egg mass, and clutch of origin and incubation water potential influenced the amount of water exchanged between the eggs and their environment during incubation and the amount of residual yolk found in hatchlings. Substrate water potential has little effect on hatchling outcomes other than the proportion of yolk converted to hatchling tissue during incubation in the rigid-shelled eggs of E. signata. It would appear that in general, the substrate water potential during incubation affects the quality of chelonian hatchlings by influencing the amount of yolk converted to hatchling tissue during embryonic development and that this influence is stronger in flexible-shelled eggs than in rigid-shelled eggs.

Microbiota bacteriana oral e lesões traumáticas no cágado Phrynops geoffroanus (Testudines, Chelidae) no sudeste do Brasil

During 2006 and 2007, we collected free-ranging Phrynops geoffroanus, from two anthropogenically altered rivers in southeastern Brazil. Oral microbiological samples were taken for isolation of aerobic and facultative anaerobic bacteria; a physical examination was performed; and we evaluated possible effects on the turtles' health. Twenty-nine species of bacteria were isolated in Piracicaba River turtles (n=10), and twenty-four species in Piracicamirim stream turtles (n=8), most of them gram-negative. In both sites, potential pathogens for reptiles were: Escherichia coli, Klebsiella pneumoniae, Enterobacter agglomerans, Citrobacter freundii, and Bacillus sp. Although boat propeller lesions were common on the carapace of the turtles, we have not found turtles with signs of clinical diseases. The oral bacterial microbiota of P. geoffroanus inhabiting the Piracicaba River basin are composed of a diverse microbe spectrum, and long-term studies of the effects of pollution and traumatic injuries on this population and its microbial flora are warranted.

Caracterización espacio-temporal del hábitat y presencia de Dermatemys mawii (Testudines: Dermatemydidae) en la cuenca del Grijalva-Usumacinta, Tabasco, México

The Central American River Turtle (Dermatemys mawii) is an endangered species that has been poorly studied. There are no reports on their population status, habitat condition, and the species distribution area is still unknown. This study analyzes the seasonal and spatial variations of their habitat and the presence/absence of D. mawii in three rivers within the Pantanos de Centla Biosphere Reserve (Tabasco, Mexico). For habitat characterization, natural segmentation of rivers was used and three sites per segment were identified, 9 in each rivers (Grijalva and Usumacinta) and 6 in Tabasquillo. Additionally, the evaluation of 11 environmental variables such as water hydrological, physicochemical characteristics and riparian and hydrophytic vegetation were carried out during two different seasons (dry and rainy). The presence/absence of species was assessed with eight fike nets that were set per segment, with a capture effort of 384 hours per trap. The capture per unit effort (CPUE) was used as an indicator of relative abundance. The results indicated spatio-temporal variations in habitat characteristics and the presence of environmental gradients. The principal components analysis (PCA) applied allowed us to determine that the first three components explained 67.8% of the environmental variability. The species presence was confirmed in all rivers, however significant differences exists in their relative abundance: the highest was registered in the Tabasquillo River where the species was present in both seasons and in all segments. Of the 11 environmental variables analyzed, the gradient, shelter and depth were the most indicative of species presence. The obtained results evidenced the importance of riparian vegetation as habitat for Dermatemys. This represents the first approach towards an action plan for a species and its habitat protection within the Pantanos de Centla Biosphere Reserve.

Hematology and serum biochemistry comparison in wild and captive Central American river turtles (Dermatemys mawii) in Tabasco, Mexico

Hematological and serum biochemistry analyses were determined on 51 Central American river turtles (Dermatemys mawii) during the dry and rainy seasons of 2006. Turtles came from two sites: Pantanos de Centla Biosphere Reserve and a turtle breeding farm, both located in Tabasco State, Mexico. Physical examination and body measures of animals were performed. Incidence and prevalence of hemoparasites were explored.Captive organisms were in poor physical condition while wild turtles were apparently healthy. There were differences in several hematological parameters related with the condition and the season. During the dry season captive turtles exhibited higher levels of uric acid and urea, as well as lower levels of glucose. Haemogregarina sp. was detected in 100% of the wild individuals, but not in captive individuals. Its incidence was greater during the rainy season. This is the first health assessment and hematology study of this critically endangered species.

Implications of river damming: the influence of aquatic hypoxia on the diving physiology and behaviour of the endangered Mary River turtle

AbstractRiver impoundments are characterized by low oxygen levels as a result of reduced water velocity and increased water depth. Bimodally respiring turtle species are likely to be highly sensitive to changes in aquatic PO2 with decreases in oxygen levels impacting upon their diving ability. The acute and long‐term effects of aquatic hypoxia on dive duration, oxygen consumption and blood respiratory properties were examined in hatchlings of the endangered Mary River turtle Elusor macrurus. It was hypothesized that acute exposure to aquatic hypoxia would cause a decrease in dive duration as a consequence of a decrease in reliance on aquatic respiration. With long‐term exposure to hypoxia, we predicted that Elu. macrurus would have the capacity to compensate for the acute effect of hypoxia and that dive duration would increase due to an increase in aquatic respiration, haemoglobin concentration and oxygen affinity (P50). When exposed to hypoxic conditions, aquatic respiration in Elu. macrurus was substantially reduced resulting in a 51% decrease in dive duration. Contrary to our predictions, Elu. macrurus hatchlings did not acclimate, and long‐term exposure to hypoxic conditions caused Elu. macrurus to lose significantly more oxygen to the hypoxic water than the normoxic acclimated turtles. The exacerbation of long‐term hypoxia on the respiratory physiology and diving ecology of Elu. macrurus raises concerns about the impacts of long‐term environmental change as a result of habitat alteration on the survival of freshwater turtle populations.

Assessing the abundance of freshwater turtles in an Australian urban landscape

Although interest in the ecological impacts of urbanisation has increased, very little is known about its impacts on freshwater turtles in Australia. This study investigated the abundance and diversity of turtles in lakes in an urbanised subtropical landscape, Brisbane, Australia. It was found that turtles were abundant throughout the lakes surveyed, with four native species and one introduced species being detected. A total of 371 individuals were captured, 77.7% of which were Brisbane River turtle (Emydura macquarii signata). The lakes surveyed were estimated to support a population of 63–269 individuals for all species combined with most lake populations containing less than 100. Turtle demographics may be classed into three stages of population growth: recovery or nascent; intermediate; and climax. Turtle reproductive success is a major concern for the survival of turtles in urban areas. Continued monitoring is needed to establish if population declines are occurring. This study suggests that while turtles are persisting in this urban environment of Australia the pressures of urbanisation, such as habitat loss, increased predation on both nests and juveniles and pollution of waterways may pose on-going risks to their survival.

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae)

O casco de Podocnemis expansa (tartaruga-da-amazônia) e Podocnemis unifilis (tracajá), os maiores quelônios de água doce da América do Sul, é uma estrutura única que diferencia esse grupo dos vertebrados atuais e está associado a alguns padrões comportamentais. O padrão dos escudos que compõem o casco dos quelônios é bastante uniforme, mas variações já foram descritas e analisadas para um grande número de espécies em todas as famílias existentes atualmente. Averiguou-se a incidência de irregularidades do padrão de escutelação no casco dessas espécies, durante os anos de 1999 a 2003 no rio Javaés, entorno do Parque Nacional do Araguaia e da Área de Proteção Ambiental Bananal/ Cantão, oeste do estado do Tocantins. P. expansa se apresenta como uma espécie mais suscetível à ocorrência de anormalidades no casco em relação a P. unifilis. Sendo que, dos 14.378 filhotes avaliados, (13,32 %) apresentavam irregularidades no padrão de escutelação enquanto que dos 1.329 filhotes de P. unifilis apenas (4,44 %). Em P. expansa, os defeitos ocorreram quase que em sua totalidade na carapaça (98,64 %) e em menor número (83,05 %) em P. unifilis.

Challenges to the Conservation of River Turtles (spp. Podocnemis) in the Peruvian Amazon

Challenges to the Conservation of River Turtles (spp. Podocnemis) in the Peruvian Amazon

Mercury bioacumulation in four tissues of Podocnemis erythrocephala (Podocnemididae: Testudines) as a function of water parameters

A number of environmental factors influence the dynamics of Hg in aquatic ecosystems, yet few studies have examined these factors for turtles, especially from South America. Red-headed river turtle ( Podocnemis erythrocephala) is easy to capture in the black waters of Rio Negro, making it the turtle species that is consumed most often by people of the region. In this study, environmental factors and turtle size were investigated to determine their influence on the Hg concentration in blood, muscle, liver and carapace of the red-headed river turtle. Factors investigated included turtle length, pH, dissolved organic carbon and availability of potential methylation sites (floodplain forests and hydromorphic soils). The study was conducted in the Rio Negro basin, where we collected water and turtle blood, muscle, liver and carapace samples from 12 tributaries for chemical analysis. Through radar imagery and existing soil maps with GIS, the percentage of alluvial floodplains and hydromorphic soils (potential methylation sites) was estimated for each drainage basin at sampling points. The mean Hg concentration in blood of P. erythrocephala was 1.64 ng g − 1 (SD = 1.36), muscle 33 ng g − 1 (SD = 11), liver 470 ng g − 1 (SD = 313) and carapace 68 ng g − 1 (SD = 32). Sex or length did not influence the Hg concentration in P. erythrocephala blood, muscle and liver, but Hg increased in carapace tissue when length size increased (ANCOVA p = 0.007). In the multiple regression analysis, none of the environmental factors studied had a significant relation with blood, muscle, liver and carapace. P. erythrocephala moves among habitats and in the open and interconnected aquatic systems of the Amazon basin, characterized by high levels of limnological variability, a good bioindicator of Hg concentration needs to be relatively sedentary to represent a specific habitat. However, the levels of Hg in liver were sufficient to pose a potential risk to humans that consume them, suggesting the usefulness of P. erythrocephala as a bioindicator.

Ecology and Status of the Magdalena River Turtle,Podocnemis lewyana, a Colombian Endemic

ABSTRACT We studied distribution, habitat selection, and reproductive ecology of the Magdalena river turtle, Podocnemis lewyana, from January to June 2003 and from January to March 2005 in the mid and low Sinu River, Cordoba, Colombia. The southern limit of its distribution occurs in the town of Carrizola, and the northern limit is near La Doctrina. We found more turtles of bigger size classes in the mid basin than in the low basin. Ninety-two individuals were observed basking in the river. Larger turtles were mostly observed in deep pools (> 3 m) with loamy or sandy bottoms, with easy access to basking sites, such as riverbanks, fallen trees, or beaches, and in areas with all types of shoreline vegetation but especially with riparian forest. Smaller turtles were found in colder, shallower, and more turbid waters than were adults, mainly in areas without riparian forest or in pastures with few trees, usually hidden in pastures flooded by the river. Adults ventured farther from shore than did juveniles. Al...

PARTICIPAÇÃO COMUNITÁRIA NA PRESERVAÇÃO DE PRAIAS PARA REPRODUÇÃO DE QUELÔNIOS NA RESERVA DE DESENVOLVIMENTO SUSTENTÁVEL MAMIRAUÁ, AMAZONAS, BRASIL

At Mamirauá Sustainable Development Reserve, river turtles are exploited by local traditional populations for decades. The nadequate use of this resource caused a striking decrease of the natural populations. Podocnemis expansa was the most affected species, followed by P. unifilis and P. sextuberculata. As a consequence, environmental authoryties introduced legal regulation, asm means to protect the most exploited species. At Mamirauá Reserve, the first step tow ards the participation of local population in the preservation of turtles was taken at the IV General Assembly of Mamirauá, where representatives of the nine sectors of villages that make Mamirauá Focal Area listed nesting beaches, and each sector selected at least one of them to be fully protected. In 1998 were recorded 272 nests at Horizonte beach: 261 of P. sextuberculata, 5 of P. unifilis and 6 of P. expansa; at Pirapucu beach 306 nests were recorded: 298 of P. sextuberculata and 8 of P. unifilis. Community participation can provide not only local political support, and lower costs for garding and enforcement of conservation rules, but also assures preservation of várzea biodiversity and maintenance of an important food item of local importance.

Development of a Polymerase Chain Reaction Test for Entamoeba invadens

Entamoeba invadens is a protozoal parasite of reptiles that causes colitis, abscesses of liver and other organs, and sometimes acute death. It is generally considered a commensal of chelonians but has also been implicated as a cause of colitis, diarrhea, and death in gopher (Gopherus polyphemus) and leopard (Geochelone pardalis) tortoises. Diagnosis of E. invadens is currently by detection of trophozoites and/or cysts upon direct fecal examination. However, definitive diagnosis of E. invadens has been difficult due to the very similar morphology of nonpathogenic Entamoeba spp., including E. ranarum, E. insolita, E. barreti, and E. terrapinae. Definitive speciation of Entamoeba spp. is important to avoid misdiagnosis or overtreatment for nonpathogenic protozoa. It is also important for consideration of mixed species reptile collections to avoid exposing snakes and lizards to E. invadens. In this study, we developed polymerase chain reaction (PCR) primers for E. invadens, E. ranarum, E. terrapinae, and E. insolita and conducted PCR amplification of purified DNA from cell cultures, as well as purified DNA from reptile stool samples with E. invadens trophozoites added. As a result of this study, a naturally occurring infection of E. invadens was confirmed in a giant South American river turtle (Podocnemis expansa). This study has developed successful PCR primers for four species of Entamoeba and demonstrates that PCR is a promising diagnostic tool for the definitive identification of E. invadens.

Thermal Plasticity of Diving Behavior, Aquatic Respiration, and Locomotor Performance in the Mary River TurtleElusor macrurus

Locomotion is a common measure of performance used in studies of thermal acclimation because of its correlation with predator escape and prey capture. However, for sedentary animals such as freshwater turtles, we propose that diving behavior may be a more ecologically relevant measure of performance. Increasing dive duration in hatchling turtles reduces predator exposure and therefore functions as an ecological benefit. Diving behavior is thermally dependent, and in some species of freshwater turtles, it is also reliant on aquatic respiration. This study examined the influence of thermal acclimation on diving behavior, aquatic respiration, and locomotor performance in the endangered, bimodally respiring Mary River turtle Elusor macrurus. Diving behavior was found to partially acclimate at 17 degrees C, with turtles acclimated to a cold temperature (17 degrees C) having a significantly longer dive duration than hatchlings acclimated to a warm temperature (28 degrees C). This increase in dive duration at 17 degrees C was not a result of physiological alterations in metabolic rate but was due instead to an increase in aquatic oxygen consumption. Increasing aquatic oxygen consumption permitted cold-acclimated hatchlings to remain submerged for significantly longer periods, with one turtle undertaking a dive of over 2.5 d. When burst-swimming speed was used as the measure of performance, thermal acclimation was not detected. Overall, E. macrurus demonstrated a partial ability to acclimate to changes in environmental temperature.

Market integration, perceived wealth and household consumption of river turtles ( Podocnemis spp.) in eastern lowland Bolivia

Written records indicate that humans in the Bolivian Amazon have utilized Podocnemis river turtles in their diets since at least the 16 th century, resulting in their decline. This study examines the potential effects of market pressures and the perception of wealth on human consumption patterns of Podocnemis unifilis and P. expansa . The hypotheses tested were: 1) there is greater market consumption of turtle protein closer to market and greater subsistence consumption of turtle protein farther away; 2) there is a negative relationship between wealth and turtle protein sale/trade such that as personal wealth increases, the consumption of turtle protein decreases. Findings suggest proximity to market does not lead to greater turtle consumption and the relationship between turtle consumption and perception of wealth is negative. The fi ndings also suggest that improved roads into communities may reduce pressure on the turtles; poorest households pose the greatest risks to turtle abundance; and culturally-specific attitudes must be addressed for effective turtle conservation and management.

NUEVOS REGISTROS DE NEMATODOS EN DOS ESPECIES DE TORTUGAS (REPTILIA: TESTUDINES) EN EL PERÚ

Registramos por primera vez para el Perú, dos especies de nematodos: Klossinemella conciliatus Alho, 1964 y Paraorientatractis semiannulata Gibbons, Khalil & Marinkelle, 1997 en Podocnemis unifilis Troschel, 1848 “taricaya”. Además, reportamos a Atractis impura Caballero, 1944 y Angusticaecum brevispiculum Chapin, 1925, en Geochelone denticulata (Linnaeus, 1766) “motelo”.

Microsatellite DNA markers for Podocnemis unifilis, the endangered yellow‐spotted Amazon River turtle

AbstractWe developed specific primers for microsatellite DNA regions of Podocnemis unifilis and tested their utility in population genetic and paternity studies on the species and other closely related Amazonian chelonians. Seventeen microsatellite loci were polymorphic in P. unifilis and all, plus two monomorphic microsatellites in P. unifilis, were polymorphic in at least one additional chelonian species, including Peltocephalus dumeriliana.

Low genetic variability in the endangered Colombian endemic freshwater turtle Podocnemis lewyana (Testudines, Podocnemididae)

The Magdalena River Turtle (Podocnemis lewyana) is a Colombian endemic species, endangered due to human exploitation and habitat destruction. To date, this species is poorly known ecologically and data on its genetic diversity are lacking. Here we report on the first genetic survey of the species across its distribution range. We obtained mitochondrial DNA sequences (488 bp) of the cytochrome b gene from 109 individuals. Samples belong to populations located at several different localities, grouped in five regions, along the four main river basins: Magdalena, Cauca, San Jorge, and Sinú drainages. We found two haplotypes, which differ in only one nucleotide substitution and which are represented with different frequencies in the five geographic regions. These results suggest that P. lewyana harbors little genetic variation and is a genetically uniform species, but more variable markers (i.e., microsatellites) should be used to unravel fine-scale phylogeographic structures in this species.