Large-scale Degradation of the Tocantins-Araguaia River Basin.

The Tocantins-Araguaia Basin is one of the largest river systems in South America, located entirely within Brazilian territory. In the last decades, capital-concentrating activities such as agribusiness, mining, and hydropower promoted extensive changes in land cover, hydrology, and environmental conditions. These changes are jeopardizing the basin's biodiversity and ecosystem services. Threats are escalating as poor environmental policies continue to be formulated, such as environmentally unsustainable hydropower plants, large-scale agriculture for commodity production, and aquaculture with non-native fish. If the current model persists, it will deepen the environmental crisis in the basin, compromising broad conservation goals and social development in the long term. Better policies will require thought and planning to minimize growing threats and ensure the basin's sustainability for future generations.

Body size predicts ontogenetic nitrogen stable-isotope (δ15N) variation, but has little relationship with trophic level in ectotherm vertebrate predators.

Large predators have disproportionate effects on their underlying food webs. Thus, appropriately assigning trophic positions has important conservation implications both for the predators themselves and for their prey. Large-bodied predators are often referred to as apex predators, implying that they are many trophic levels above primary producers. However, theoretical considerations predict both higher and lower trophic position with increasing body size. Nitrogen stable isotope values (δ15N) are increasingly replacing stomach contents or behavioral observations to assess trophic position and it is often assumed that ontogenetic dietary shifts result in higher trophic positions. Intraspecific studies based on δ15N values found a positive relationship between size and inferred trophic position. Here, we use datasets of predatory vertebrate ectotherms (crocodilians, turtles, lizards and fishes) to show that, although there are positive intraspecific relationships between size and δ15N values, relationships between stomach-content-based trophic level (TPdiet) and size are undetectable or negative. As there is usually no single value for 15N trophic discrimination factor (TDF) applicable to a predator species or its prey, estimates of trophic position based on δ15N in ectotherm vertebrates with large size ranges, may be inaccurate and biased. We urge a reconsideration of the sole use of δ15N values to assess trophic position and encourage the combined use of isotopes and stomach contents to assess diet and trophic level.

Enterobacteriaceae associated with eggs of Podocnemis expansa and Podocnemis unifilis (Testudines:Chelonia) in nonpolluted sites of national park of Araguaia Plains, Brazil.

Fertile eggs of Podocnemis expansa and Podocnemis unifilis were investigated for the presence of enterobacteria, as these two endangered species have the potential for conservation measures that include egg transfer. Knowledge of normal microflora associated with turtles and turtle eggs would help effectively manage the transfer of these eggs among institutions. Thirty eggs of each species were collected, aseptically transferred, cracked inside plastic bags containing tetrathionate broth, and spread on selective media plates. Ten samples of sand and water were also examined for the presence of fecal coliforms using Colilert Quanti-Tray kits. Enterobacteriaceae were identified using an API 20E biochemical test kit. A majority of the bacteria isolated were potential pathogens. All egg samples were positive for Enterobacteriaceae, among which 15 eggs of P. expansa were positive for Shigella flexneri. Other isolates included Chromobacterium violaceum, Escherichia coli, and Aeromonas salmonicida subsp. salmonicida. Eggs of P. unifilis were most frequently positive for Shigella flexneri and C. violaceum, and less frequently positive for A. salmonicida subsp. salmonicida and Salmonella choleraesuis subsp. arizonae. The source of the bacteria in these eggs is unknown, but the nesting beaches were considered a source as water samples had low total coliform counts and E. coli was isolated from only one sand sample. This study demonstrated that Enterobacteriaceae are part of the indigenous microflora of chelonians.

Parasitization by Sauroplasma sp. (Apicomplexa: Haemohormidiidae) in Chelonian Podocnemis expansa (Testudines: Podocnemididae) in the Brazilian Amazon.

The prevalence and parasitemia of the piroplasm Sauroplasma sp. were evaluated in the Amazon chelonian Podocnemis expansa in Brazil. Samples were collected from 75 chelonians from 3 locations, including a commercial breeding facility, an indigenous subsistence breeding facility, and a wild population. Sauroplasma were found in 72% (54/75) of the chelonians, and the prevalence varied among the sampling sites. No significant correlations were found between the prevalence and the sex and body condition index of the chelonians. The mean parasitemia rate was 44.14/2,000 erythrocytes (2.2%), and no significant correlation was found between the parasitemia and sex and body condition index of the chelonians. These results suggest that the parasite is not pathogenic to P. expansa. No ectoparasites were found in the animals evaluated in the present study; however, due to the aquatic habit of the chelonian, it is likely that the piroplasm is transmitted by leeches and not by ticks, as would be expected for piroplasms.

Prevalence and parasitemia of Haemogregarina sp. in Podocnemis expansa (Testudines: Podocnemididae) from the Brazilian Amazon.

Seventy-five turtles Podocnemis expansa in the Brazilian Amazon were examined for the presence of ectoparasites and hemoparasites. Samplings were performed in three study areas in the state of Tocantins, Brazil. Twenty-five specimens were sampled per study area (a commercial breeding facility, an indigenous subsistence breeding facility and a wild population of the Javaés River). Hemoparasites of the genus Haemogregarina were found in 66% (50/75) of the turtle specimens, and the infections were restricted to the commercial breeding facility and to the wild population of the Javaés River. The mean level of parasitemia was 54/2,000 erythrocytes (2%). There was no correlation between the body condition index of the chelonians and the level of parasitemia, with no significant difference between genders. No leeches were observed during the physical exams in any of the study areas, but the specimens from the commercial breeding facility were in poor physical condition with shell deformities and the presence of a relatively high amount of skin ulcerations, most likely caused by fungi and bacteria. This was the first study to record the occurrence of hemogregarines on a population scale in P. expansa and helps to increase knowledge about hemoparasites in chelonians in Brazil.

Ontogeny of the shell bones of embryos of Podocnemis unifilis (Troschel, 1848) (Testudines, Podocnemididae).

The aim of the present study was to investigate the sequence of shell bone formation in the embryos of the Pleurodira, Podocnemis unifilis. Their bones and cartilage were collected and cleared before staining. The shell was also examined by obtaining a series of histological slices. All the bony elements of the plastron have independent ossification centers, which subsequently join together and retain two fontanelles until the period of hatching. This turtle has a mesoplastra, which is characteristic of the Podocnemididae. The carapace begins to form concurrently with the ossification of the ribs at the beginning of stage 20. All the plates, except the suprapygal, initiate ossification during the embryonic period. The main purpose of the histological investigation was to highlight the relationship between the formation of the carapace and ribs with that of the neural plates. The costal and neural plates were found not to independent ossification centers, but to be closely related to components of the endoskeleton, originating as expansions of the perichondral collar of the ribs and the neural arches, respectively. Considering the ribs as an endoskeletal element of the carapace, the carapace and plastron begin ossification at the same stage in P. unifilis. This pattern reveals similarities with other Pleurodira, as well as evident variations, such as the presence of the seven neural bones and the presence of only one ossification center in the nuchal plate.

Prevalence and parasitemia of Haemogregarina sp. in Podocnemis expansa (Testudines: Podocnemididae) from the Brazilian Amazon / Prevalência e parasitemia de Haemogregarina sp. em Podocnemis expansa (Testudines: Podocnemididae) da Amazônia Brasileira

Seventy-five turtles Podocnemis expansa in the Brazilian Amazon were examined for the presence of ectoparasites and hemoparasites. Samplings were performed in three study areas in the state of Tocantins, Brazil. Twenty-five specimens were sampled per study area (a commercial breeding facility, an indigenous subsistence breeding facility and a wild population of the Javaés River). Hemoparasites of the genus Haemogregarina were found in 66% (50/75) of the turtle specimens, and the infections were restricted to the commercial breeding facility and to the wild population of the Javaés River. The mean level of parasitemia was 54/2,000 erythrocytes (2%). There was no correlation between the body condition index of the chelonians and the level of parasitemia, with no significant difference between genders. No leeches were observed during the physical exams in any of the study areas, but the specimens from the commercial breeding facility were in poor physical condition with shell deformities and the presence of a relatively high amount of skin ulcerations, most likely caused by fungi and bacteria. This was the first study to record the occurrence of hemogregarines on a population scale in P. expansa and helps to increase knowledge about hemoparasites in chelonians in Brazil.

Setenta e cinco tartarugas Podocnemis expansa foram examinadas para a presença de ectoparasitos e hemoparasitos na região amazônica brasileira. As coletas foram realizadas no Estado do Tocantins, Brasil. No estudo foram amostrados 25 indivíduos por local, um criatório comercial, um criatório de subsistência indígena e uma população silvestre do rio Javaés. Foram encontrados hemoparasitos pertencentes ao gênero Haemogregarina em 66% (50/75) dos animais, sendo que as infecções foram restritas ao criatório comercial e a população silvestre do rio Javaés. A parasitemia média foi de 54/2.000 eritrócitos (2%). Não houve relação entre o índice de condição corporal dos quelônios e os níveis de parasitemia e nem diferença quanto ao sexo dos animais. Não foram observadas sanguessugas durante os exames físicos, porém os animais do criatório comercial apresentaram condições físicas ruins com deformidades no casco e presença de uma quantidade relativamente alta de ulcerações na pele, provavelmente causadas por fungos ou bactérias. Este estudo registrou a primeira ocorrência de hemogregarinas em uma escala populacional de P. expansa e contribui para expandir o conhecimento de hemoparasitos em quelônios no Brasil.

Morfometria e histologia das gônadas de machos e fêmeas recém-eclodidos de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) / Morphometry and histology of the gonads of males and females hatchlings of Podocnemis expansa and Podocnemis. unifilis (Testudines, Podocnemididae)

Considerando a importância da técnica histológica na sexagem de quelônios e os poucos trabalhos direcionados para esta técnica, é proposto neste estudo caracterizar morfometricamente e histologicamente as gônadas de P. expansa e P. unifilis. Todos os espécimes utilizados neste trabalho foram procedentes do rio Javaés, entorno do Parque Nacional do Araguaia, Estado do Tocantins, Brasil. Após estudo sob estereomicroscópio, foram coletadas as gônadas para o procedimento histológico de rotina. Foram analisadas 187 amostras de P. expansa, das quais 81,2% foram identificadas como fêmeas e 18,7% como machos; e 98 de P. unifilis, das quais 31,6% eram fêmeas e 68,4% machos. Não foram verificadas diferenças microscópicas relevantes na sexagem entre estas espécies. Os critérios utilizados no diagnóstico microscópico foram principalmente a morfologia das gônadas, a presença do apêndice no oviduto remanescente, a morfologia do oviduto e as características das células de revestimento dos folículos e túbulos seminíferos. Quando comparadas as medidas biométricas dos ovários e testículos, somente foram observadas diferenças para a largura.

Considering the importance of the histological sexing technique of turtles and the few works directed to this objective, it was proposed in this study to morphometrically and histologically characterize the gonads of P. unifilis and P. expansa. All specimens used in this work originated in the Javaés river, around the Araguaia National Park, Tocantins State, Brazil. Following a study under a stereoscope, the gonads were collected for the routine histological procedure. A total of 187 samples of P. expansa were analyzed, of which 81.2% were identified as female and 18.7% as male; as well as 98 P. unifilis samples, of which 31.6% were female and 68.4% males. No relevant microscopic differences were verified in the sexing between these species. The criteria used in the microscopically diagnosis were primarily gonad morphology, presence of the appendix in the remaining oviduct, oviduct morphology and the characteristics of covering cells of the follicles and somniferous tubules. When the measurements of the ovaries and testicles were compared, only differences in width were observed.

Morfometria e histologia das gônadas de machos e fêmeas recém-eclodidos de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) - doi: 10.4025/actascibiolsci.v34i1.7257

Considering the importance of the histological sexing technique of turtles and the few works directed to this objective, it was proposed in this study to morphometrically and histologically characterize the gonads of P. unifilis and P. expansa. All specimens used in this work originated in the Javaés river, around the Araguaia National Park, Tocantins State, Brazil. Following a study under a stereoscope, the gonads were collected for the routine histological procedure. A total of 187 samples of P. expansa were analyzed, of which 81.2% were identified as female and 18.7% as male; as well as 98 P. unifilis samples, of which 31.6% were female and 68.4% males. No relevant microscopic differences were verified in the sexing between these species. The criteria used in the microscopically diagnosis were primarily gonad morphology, presence of the appendix in the remaining oviduct, oviduct morphology and the characteristics of covering cells of the follicles and somniferous tubules. When the measurements of the ovaries and testicles were compared, only differences in width were observed

P. expansa e P. unifilis. Todos os espécimes utilizados neste trabalho foram procedentes do rio Javaés, entorno do Parque Nacional do Araguaia, Estado do Tocantins, Brasil. Após estudo sob estereomicroscópio, foram coletadas as gônadas para o procedimento histológico de rotina. Foram analisadas 187 amostras de P. expansa, das quais 81,2% foram identificadas como fêmeas e 18,7% como machos; e 98 de P. unifilis, das quais 31,6% eram fêmeas e 68,4% machos. Não foram verificadas diferenças microscópicas relevantes na sexagem entre estas espécies. Os critérios utilizados no diagnóstico microscópico foram principalmente a morfologia das gônadas, a presença do apêndice no oviduto remanescente, a morfologia do oviduto e as características das células de revestimento dos folículos e túbulos seminíferos. Quando comparadas as medidas biométricas dos ovários e testículos, somente foram observadas diferenças para a largura

Predação de fêmeas adultas de Podocnemis expansa Schweigger (Testudines, Podocnemididae) por Panthera onca Linnaeus (Carnivora, Felidae), no Estado do Tocantins / Predation on adult females of Podocnemis expansa Schweigger (Testudines, Podocnemididae) by Panthera onca Linnaeus (Carnivora, Felidae), in Tocantins State

Podocnemis expansa (tartaruga-da-amazônia) é o maior e mais importante representante da fauna de quelônios da Amazônia devido à sua importância econômica como fonte alimentar para as populações indígenas e ribeirinhas desta região. Apesar disso, os aspectos relacionados à sua biologia reprodutiva, assim como os índices de predação natural de animais adultos em seu habitat são pouco conhecidos. Nessa pesquisa foi averiguado o número de fêmeas de P. expansa predadas por Panthera onca (onça-pintada) em um rio da Amazônia Brasileira. A onça-pintada é o único predador das fêmeas adultas de P. expansa nas praias do rio Javaés, Estado do Tocantins, predando em média 3,66 por cento das fêmeas em postura. A predação se dá sempre à noite, quando as fêmeas sobem às praias para nidificar.

Podocnemis expansa (Amazonian giant River turtle) is the largest and more important representative of the Amazonian turtle's fauna because their economic importance as food resource to the indigenous and riverine populations. Aspects related to their reproductive biology, and natural predation of adults in its habitat are poorly known. In order to estimate the predation rates of females of P. expansa we have registered the number of turtles with signs of been killed by Panthera onca (jaguar) in a River of the Brazilian Amazon. Jaguar was the only predator of the adult females of P. expansa in the Javaés River beaches (Tocantins State), predating about 3.66 percent of the females (33 of 901). Predation always happens at night, when females leave water in order to nest.

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) / Evaluation of irregular pattern of the shell scutes in Podocnemis expansa and 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 por cento) apresentavam irregularidades no padrão de escutelação enquanto que dos 1.329 filhotes de P. unifilis apenas (4,44 por cento). Em P. expansa, os defeitos ocorreram quase que em sua totalidade na carapaça (98,64 por cento) e em menor número (83,05 por cento) em P. unifilis.

The shell of Podocnemis expansa (Amazonian giant River turtle) and Podocnemis unifilis (Yellow-spotted Amazon River Turtle), the largest South American turtles, is a unique structure that differentiates them from other known vertebrates; and it is associated with some of their behavioral patterns. Their scute pattern is quite uniform however variations have been described and analyzed for a great number of other species of existing families. In the Javaés River, from 1999 to 2003, we observed an occurrence of abnormalities in their scute pattern. This was in the vicinity of the Araguaia National Park and the Bananal/ Cantão Environment Protected Area, west of Tocantins state. Of the both species, P. expansa is more susceptible to shell abnormalities. Of 14.378 P. expansa hatchlings observed, 13.32 percent presented scute pattern abnormalities, while of 1.329 P. unifilis hatchlings, only 4.44 percent. The incidence of abnormalities occurred only in the carapace, namely, 98.64 percent in P. expansa, and 83.05 percent in P. unifilis.

Avaliação da predação de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) no rio Javaés, Tocantins

Podocnemis expansa and P. unifilis long lived with late sexual maturation, which influences a low replacement rate of individuals. Their populations are characterized by low adults mortality, but high mortality of embryos and hatchlings. The natural nest predation is an important factor for hatchling success. In Javaés River, the eggs and hatchlings can be predated by a large number of animals such as birds, vultures (Coragyps atratus and Cathartes aura), carcará (Polyborus plancus), jabiru (Jabiru mycteria); lizards (Tupinambis teguixin) and small mammals, coati (Nasua nasua) and crab-eating-fox (Cerdocyon thous). About 65,98% of nests of P. unifilis are predated (41,68% totally and 24,30% partially). Only 5,31% of P. expansa nests are partially predated. There are many aquatic predators, like carnivorous fish, mainly piranhas (Serrasalmus nattereri) and caimans (Melanosuchus niger e Caimam crocodilus). The predators of P. unifilis females are: black caiman (Melanosuchus niger), jaguar (Panthera onca) and puma (Puma concolor), and of P. expansa females is the P. onca. In average 3,93% of P. unifilis females are predated annually while that to P. expansa the average is 5,66%.

Podocnemis expansa e P. unifilis são animais de vida longa, com uma demorada maturação sexual, o que influencia uma baixa taxa de substituição de indivíduos. Suas populações são caracterizadas por uma pequena mortalidade dos animais adultos, mas alta taxa de mortalidade de filhotes e embriões. Sendo a predação natural de ninhos e filhotes um dos fatores mais importantes do baixo sucesso de eclosão dessas espécies. No rio Javaés, os ovos e recém-eclodidos podem ser predados por uma grande diversidade de animais: dentre as aves, urubus (Coragyps atratus e Cathartes aura), carcará (Polyborus plancus), jaburu (Jabiru mycteria); lagartos (Tupinambis teguixin) e mamíferos de pequeno porte, coati (Nasua nasua) e cachorro-do-mato (Cerdocyon thous). Do total anual de desovas de P. unifilis em média 65,98% são predadas, sendo 41,68% de forma total e 24,30% parcialmente. Enquanto que apenas 5,31% das ninhadas de P. expansa são sempre parcialmente predadas. Dentre os predadores aquáticos existem diversos peixes, principalmente piranhas (Serrasalmus nattereri) e jacarés (Melanosuchus niger e Caimam crocodilus). Os predadores das fêmeas de P. unifilis são: jacaré-açu (Melanosuchus niger), onça-pintada (Panthera onca) e onça-parda (Puma concolor). Enquanto que as fêmeas de P. expansa em postura, somente são predadas por P. onca. As fêmeas de P. unifilis em postura são predadas num total médio de 3,93% anualmente, enquanto que para P. expansa a média anual é 5,66% das fêmeas.

Avaliação da predação de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) no rio Javaés, Tocantins / Evaluation of predation in Podocnemis expansa and Podocnemis unifilis (Testudines, Podocnemididae) in the Javaés River, Tocantins

Podocnemis expansa e P. unifilis são animais de vida longa, com uma demorada maturação sexual, o que influencia uma baixa taxa de substituição de indivíduos. Suas populações são caracterizadas por uma pequena mortalidade dos animais adultos, mas alta taxa de mortalidade de filhotes e embriões. Sendo a predação natural de ninhos e filhotes um dos fatores mais importantes do baixo sucesso de eclosão dessas espécies. No rio Javaés, os ovos e recém-eclodidos podem ser predados por uma grande diversidade de animais: dentre as aves, urubus (Coragyps atratus e Cathartes aura), carcará (Polyborus plancus), jaburu (Jabiru mycteria); lagartos (Tupinambis teguixin) e mamíferos de pequeno porte, coati (Nasua nasua) e cachorro-do-mato (Cerdocyon thous). Do total anual de desovas de P. unifilis em média 65,98% são predadas, sendo 41,68% de forma total e 24,30% parcialmente. Enquanto que apenas 5,31% das ninhadas de P. expansa são sempre parcialmente predadas. Dentre os predadores aquáticos existem diversos peixes, principalmente piranhas (Serrasalmus nattereri) e jacarés (Melanosuchus niger e Caimam crocodilus). Os predadores das fêmeas de P. unifilis são: jacaré-açu (Melanosuchus niger), onça-pintada (Panthera onca) e onça-parda (Puma concolor). Enquanto que as fêmeas de P. expansa em postura, somente são predadas por P. onca. As fêmeas de P. unifilis em postura são predadas num total médio de 3,93% anualmente, enquanto que para P. expansa a média anual é 5,66% das fêmeas.

Podocnemis expansa and P. unifilis long lived with late sexual maturation, which influences a low replacement rate of individuals. Their populations are characterized by low adults mortality, but high mortality of embryos and hatchlings. The natural nest predation is an important factor for hatchling success. In Javaés River, the eggs and hatchlings can be predated by a large number of animals such as birds, vultures (Coragyps atratus and Cathartes aura), carcará (Polyborus plancus), jabiru (Jabiru mycteria); lizards (Tupinambis teguixin) and small mammals, coati (Nasua nasua) and crab-eating-fox (Cerdocyon thous). About 65,98% of nests of P. unifilis are predated (41,68% totally and 24,30% partially). Only 5,31% of P. expansa nests are partially predated. There are many aquatic predators, like carnivorous fish, mainly piranhas (Serrasalmus nattereri) and caimans (Melanosuchus niger e Caimam crocodilus). The predators of P. unifilis females are: black caiman (Melanosuchus niger), jaguar (Panthera onca) and puma (Puma concolor), and of P. expansa females is the P. onca. In average 3,93% of P. unifilis females are predated annually while that to P. expansa the average is 5,66%.