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.

Mercury biomagnification in the food chain of a piscivorous turtle species (Testudines: Chelidae: Chelus fimbriata) in the Central Amazon, Brazil.

Due to their natural history and ecological attributes, turtles are excellent organisms for studies of heavy metal contamination. Turtles have a large geographical distribution, occupy different aquatic habitats, and occupy various trophic levels. The present study investigated mercury bioaccumulation in the carnivorous chelonian Chelus fimbriata (Matamata turtle) and Hg biomagnification in relation to its aquatic food chain in the middle Rio Negro, AM-Brazil. Tissue samples of muscle, carapace and claws were collected from 26 C. fimbriata individuals, as well as collections of autotrophic energy sources found in the turtle's aquatic habitat area. The samples were collected in February-March/2014 and analyzed for THg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes. The highest THg levels were found in claws (3780 ng.g-1), carapace (3622 ng.g-1) and muscle (403 ng.g-1), which were found to be significantly different [F(2.73) = 49.02 p < 0.01]. However, THg concentrations in muscle tissue were below the consumption threshold indicated by the WHO and Brazilian Health Ministry. The average δ13C and δ15N values in Matamata samples were -31.7‰ and 11.9‰, respectively. The principal energy source sustaining the food chain of C. fimbriata was found to be terrestrial shrubs, with smaller contributions from emergent aquatic herbaceous plants and algae, while δ15N values showed its trophic position to be two levels above the autotrophic energy sources. There was a positive correlation between THg and turtle size, while a significant relationship was found between THg and δ15N, showing strong biomagnification in the food chain of C. fimbriata: y = 0.21x + 0.46; r2 = 0.45; p < 0.001, for which the slope presented a value of 0.21.

Distribution of copper in the Atlantic and Pacific Oceans using green turtles (Chelonia mydas) as a bioindicator.

Marine pollution by trace elements is a global concern due to potential toxicity to species and ecosystems. Copper is a fundamental trace element for many organisms; however, it becomes toxic at certain concentrations. The green turtle (Chelonia mydas) is a good sentinel species, due to its circumglobal distribution, long life cycle, coastal habits when juvenile, and is subject to environmental pollution. Quantifying and comparing copper levels makes it possible to understand the availability of this trace element in nature. During this research, comparisons were made between the levels of copper found in the liver, kidneys, and muscles of 35 turtles, from the United States (Hawaii and Texas), Brazil, and Japan. Copper was found in all specimens. In the liver, animals from Hawaii (91.08 µg g-1), Texas (46.11 µg g-1), and Japan (65.18 µg g-1) had statistically equal means, while those from Brazil (16. 79 µg g-1) had the lowest means. For the kidney, copper means were statistically equal for all Hawaii (3.71 µg g-1), Texas (4.83 µg g-1), Japan (2.47 µg g-1), and Brazil (1.89 µg g-1). In muscle, the means between Texas (0.75 µg g-1) and Japan (0.75 µg g-1) were the same, and the mean for Brazil (0.13 µg g-1) was the lowest. Among the organs, the highest levels of copper were found in the liver (28.33 µg g-1) followed by the kidney (2.25 µg g-1) and with the lowest levels in the muscle (0.33 µg g-1). This is the first study of copper levels among marine vertebrates in distant parts of the globe using similar comparative filters between different locations. Similar levels in turtles from such distant locations may indicate that there is a pantropical pattern of copper distribution in the biota, and that these animals are subject to the process of bioavailability of this metal in the environment and metabolic regulation.

Pantropical distribution of zinc in green turtles (Chelonia mydas): marine vertebrates as sentiel species.

Pollution is one of the biggest threats to marine life and trace elements are among the most toxic pollutants in this environment. Zn is an essential trace element for biota but becomes toxic at high concentrations. Sea turtles are good bioindicators of trace element pollution, due to their longevity and cosmopolitan distribution that allow bioaccumulation for years in their tissues. Determining and comparing Zn concentrations in sea turtles from faraway places is relevant for conservation due to the lack of knowledge of geographically broader distribution patterns of Zn in vertebrates. In this study, comparative analyses of bioaccumulation in the liver, kidney, and muscles of 35 C. mydas from Brazil, Hawaii, the USA (Texas), Japan, and Australia of statistically equal sizes were performed. Zn was found in all specimens, with the highest levels in the liver and kidneys. Specimens from Australia (30.58 µg g-1), Hawaii (31.91 µg g-1), Japan (29.99 µg g-1), and the USA (33.79 µg g-1) showed statistically equal means in the liver. Kidney levels were the same in Japan (35.09 µg g-1) and the USA (37.29 µg g-1) and the same in Australia (23.06 µg g-1) and Hawaii (23.31 µg/g). Specimens from Brazil had the lowest means in both organs (12.17 µg g-1 in the liver and 9.39 µg g-1 in the kidney). The pattern of equal Zn values for most specimens in the liver is an important finding, demonstrating that there are pantropical patterns in the distribution of this metal even in regions so far from each other. A possible explanation is due to the essential nature of this metal linked to metabolic regulation, in addition to the bioavailability for biological absorption in marine environments, such as RS in Brazil, with a lower standard bioavailability also found in other organisms. Therefore, factors such as metabolic regulation and bioavailability indicate that there is a pantropical distribution of Zn in marine biota and green turtles can be a useful model as a sentinel species.

Life after death? Exploring biochemical and molecular changes following organismal death in green turtles, Chelonia mydas (Linnaeus, 1758).

Green turtles, Chelonia mydas, have been included in biomonitoring efforts given its status as an endangered species. Many studies, however, rely on samples from stranded animals, raising the question of how death affects important biochemical and molecular biomarkers. The goal of this study was to investigate post mortem fluctuations in the antioxidant response and metabolism of carbohydrates in the liver of C. mydas. Liver samples were obtained from six green turtles which were submitted to rehabilitation and euthanized due to the impossibility of recovery. Samples were collected immediately after death (t = 0) and at various time intervals (1, 2, 3, 4, 5, 6, 12, 18 and 24 h post mortem), frozen in liquid nitrogen and stored at -80 °C. The activities of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) were analyzed, as were the levels of lipid peroxidation, glycogen concentration, RNA integrity (RNA IQ) and transcript levels of carbonic anhydrase and pyruvate carboxylase genes. Comparison between post mortem intervals showed a temporal stability for all the biomarkers evaluated, suggesting that changes in biochemical and molecular parameters following green turtle death are not immediate, and metabolism may remain somewhat unaltered up to 24 h after death. Such stability may be associated with the overall lower metabolism of turtles, especially under an oxygen deprivation scenario such as organismal death. Overall, this study supports the use of biomarkers in sea turtles sampled within a period of 24 h post mortem for biomonitoring purposes, though it is recommended that post mortem fluctuations of particular biomarkers be evaluated prior to their application, given that proteins may show varying degrees of susceptibility to proteolysis.

Coastal degradation impacts on green turtle's (Chelonia mydas) diet in southeastern Brazil: Nutritional richness and health.

This study evaluated the influence of environmental degradation on the nutritional value of the main marine macrophytes consumed by green sea turtles (Chelonia mydas) in areas with different degrees of urbanization. Macrophyte assemblages in the highly urbanized area (HUa) showed lower richness compared to the lightly urbanized area (LUa) (Mann-Whitney U test: 10.0 ± 3.6 SD genera and 11.9 ± 4.2 taxa per transect vs. 20.1 ± 7.0 genera and 23.5 ± 9.2 taxa per transect) respectively. Also, diet was poorer with 4.0 ± 1.6 genera per turtle (vs. 8.5 ± 4.0 in HUa) and less diverse with Shannon index of diversity = 0.45 ± 0.29 (vs. 0.64 ± 0.46 in LUa). Body condition was similar in both areas. About half of individuals were classified as having normal body condition, 14-15% as underweight and 23-34% as being emaciated. Fibropapillomatosis prevalence (χ2 = 8.720; n = 222; df = 1; p = 0.003) was higher in the HUa but, in affected animals, severity was marginally non-significant (χ2 = 5.721; n = 82; df = 2; p = 0.057). Significant differences in energy content (kcal) were detected between areas in both summer (S) and winter (W). All ANOVAs on total lipids (F = 22.15 [S] and 30.39 [W]), total water-soluble proteins (F = 327.65 [S] and 64.42 [W]) and total carbohydrates (F = 70.90 [S] and 27.62 [W]) showed high significance (p < 0.001). Carotenoids concentration yielded significant results for Halodule in summer and Hypnea in winter (ANOVAs, F = 39.42 and 13.07, respectively). For both, tests revealed that concentration was higher in LUa than HUa. High levels of phycobiliproteins and proteins in this area probably reflect nitrogen accumulation. Frequency and severity of fibropapillomatosis suggest that urbanization-caused alterations in species diversity and in chemical composition of marine plants affect green turtles' health. LIGHT ABSTRACT: The use of coastal areas by humanity is widespread and increasing. The impacts caused to the coastal environment, be it terrestrial, estuarine or marine, are important and affect numerous species. Our study evaluated the influence of environmental degradation on the nutritional value of the main algae eaten by the green turtle, one of the very few marine megaherbivores (those herbivores with body mass above 10 kg). Diet in the highly urbanized area was richer in proteins, lipids and carbohydrates (sugars) and lower in carotenoids (photosynthetic and photoprotectant pigments in algae and plants; precursors of vitamin A involved in oxygen transport in animals-animals do not synthetize such molecules). High levels in phycobiliproteins (photosynthetic pigments present in some algae) and proteins in the highly urbanized area probably result from organic pollution and nitrogen accumulation in coastal waters. Nitrogen compounds dissolved in water are a threat to vertebrates due to its toxicity and negative effects on the immune system. Our results suggest that algae chemical composition and severity of fibropapillomatosis (tumors caused by a herpesvirus in green sea turtles) are directly related through environmental alterations caused by urbanization.

Health condition of Chelonia mydas from a foraging area affected by the tailings of a collapsed dam in southeast Brazil.

In 2015, the failure of the Fundão dam caused the release of 43 million m3 of tailings into the Doce River Basin, in southeast Brazil. It was considered the largest environmental disaster of the world mining industry. The tailings, composed mostly of heavy metals, caused massive destruction of the Doce River ecosystem endangering the organisms that live in the coastal zone where the mud reached the ocean. Among the exposed species are the sea turtles that use the region for food. The aim of this study was to evaluate the effect of contaminants on the health status of juvenile green sea turtles that feed in a coastal area exposed to ore mud (Santa Cruz) and to compare them with animals from an area not directly affected (Coroa Vermelha). A physical examination was performed to determine the health status. Blood samples were analyzed for hematological and biochemical parameters, and metal concentrations (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn). Santa Cruz sea turtles had more ectoparasites and a higher incidence of fibropapillomatosis. Statistically significant differences between sites were found for levels of calcium, phosphorus, glucose, protein, albumin, globulin, cholesterol, triglycerides, urea, CPK, ALT, and AST. The count of leukocytes, thrombocytes, and heterophils, as well as the concentrations of As and Cu were higher in Santa Cruz turtles. Together the results show a worse nutritional status and a greater degree of liver and kidney damage in animals affected by the tailings. The health status may indicate a physiological deficit that can affect their immune system and behavior, which is supported by the higher fibropapillomatosis tumor score and ectoparasite load in these animals. These results support the need for long-term monitoring of the exposed area to quantify the direct and indirect influence of the heavy metals levels on sea turtles and how this reflects the environmental health.

Characterisation of UDP-glucuronosyltransferase activity in sea turtle Chelonia mydas.

Uridine diphosphate glucuronosyltransferase (UGT) enzymes conjugate many lipophilic chemicals, such as drugs, environmental contaminants, and endogenous compounds, promoting their excretion. The complexity of UGT kinetics, and the location of enzyme active site in endoplasmic reticulum lumen, requires an accurate optimisation of enzyme assays.In the present study, we characterised UGT activity in liver microsomes of green turtles (Chelonia mydas), an endangered species. The conditions for measuring UGT activity were standardised through spectrofluorimetric methods, using the substrates 4-methylumbelliferone (4-MU) and uridine diphosphate glucuronic acid (UDPGA) at 30 °C and pH 7.4.The green turtles showed UGT activity at the saturating concentrations of substrates of 250 µM to 4-MU and 7 mM to UDPGA. The alamethicin, Brij®58, bovine serum albumin (BSA), and magnesium increased UGT activity. The assay using alamethicin (22 µg per mg of protein), magnesium (1 mM), and BSA (0.25%) reached the highest Vmax (1203 pmol·min-1mg·protein-1). Lithocholic acid and diclofenac inhibited UGT activity in green turtles.This study is the first report of UGT activity in the liver of green turtles and provides a base for future studies to understand the mechanisms of toxicity by exposure to contaminants in this charismatic species.

Enhanced resistance to Ca2+-induced mitochondrial permeability transition in the long-lived red-footed tortoise Chelonoidis carbonaria.

The interaction between supraphysiological cytosolic Ca2+ levels and mitochondrial redox imbalance mediates the mitochondrial permeability transition (MPT). The MPT is involved in cell death, diseases and aging. This study compared the liver mitochondrial Ca2+ retention capacity and oxygen consumption in the long-lived red-footed tortoise (Chelonoidis carbonaria) with those in the rat as a reference standard. Mitochondrial Ca2+ retention capacity, a quantitative measure of MPT sensitivity, was remarkably higher in tortoises than in rats. This difference was minimized in the presence of the MPT inhibitors ADP and cyclosporine A. However, the Ca2+ retention capacities of tortoise and rat liver mitochondria were similar when both MPT inhibitors were present simultaneously. NADH-linked phosphorylating respiration rates of tortoise liver mitochondria represented only 30% of the maximal electron transport system capacity, indicating a limitation imposed by the phosphorylation system. These results suggested underlying differences in putative MPT structural components [e.g. ATP synthase, adenine nucleotide translocase (ANT) and cyclophilin D] between tortoises and rats. Indeed, in tortoise mitochondria, titrations of inhibitors of the oxidative phosphorylation components revealed a higher limitation of ANT. Furthermore, cyclophilin D activity was approximately 70% lower in tortoises than in rats. Investigation of critical properties of mitochondrial redox control that affect MPT demonstrated that tortoise and rat liver mitochondria exhibited similar rates of H2O2 release and glutathione redox status. Overall, our findings suggest that constraints imposed by ANT and cyclophilin D, putative components or regulators of the MPT pore, are associated with the enhanced resistance to Ca2+-induced MPT in tortoises.

Skeletal muscle histidine-containing dipeptide contents are increased in freshwater turtles (C. picta bellii) with cold-acclimation.

Freshwater turtles found in higher latitudes can experience extreme challenges to acid-base homeostasis while overwintering, due to a combination of cold temperatures along with the potential for environmental hypoxia. Histidine-containing dipeptides (HCDs; carnosine, anserine and balenine) may facilitate pH regulation in response to these challenges, through their role as pH buffers. We measured the HCD content of three tissues (liver, cardiac and skeletal muscle) from the anoxia-tolerant painted turtle (C. picta bellii) acclimated to either 3 or 20 °C. HCDs were detected in all tissues, with the highest content shown in the skeletal muscle. Turtles acclimated to 3 °C had more HCD in their skeletal muscle than those acclimated to 20 °C (carnosine = 20.8 ± 4.5 vs 12.5 ± 5.9 mmol·kg DM-1; ES = 1.59 (95%CI: 0.16-3.00), P = 0.013). The higher HCD content shown in the skeletal muscle of the cold-acclimated turtles suggests a role in acid-base regulation in response to physiological challenges associated with living in the cold, with the increase possibly related to the temperature sensitivity of carnosine's dissociation constant.

Determination of dopamine, noradrenaline, and adrenaline in Krebs-Henseleit solution by liquid chromatography coupled with tandem mass spectrometry and measurement of their basal release from Chelonoidis carbonaria aortae in vitro.

This study presented for the first time the development and validation of a sensitive method for quantification of dopamine, noradrenaline, and adrenaline in Krebs-Henseleit solution by LC-tandem mass spectrometry. Aliquots of 2.0 mL calibrators, quality controls, and samples of Krebs-Henseleit solution incubated with tortoise's aortic ring for 30 min were extracted by solid-phase extraction. Catecholamine separation was achieved on a 100 × 4.6 mm LiChrospher RP-8 column and the quantification was performed by a mass spectrometer equipped with an electrospray interface operating in positive ion mode. The run time was 4 min and the calibration curve was linear over the range of 0.1-20.0 ng/mL. The method was applied to the measurement of basal release of dopamine, noradrenaline, and adrenaline from the tortoise Chelonoidis carbonaria aortae in vitro. One aortic ring (30 mm) per tortoise (n = 5) was incubated for 30 min in a 5 mL organ bath filled with Krebs-Henseleit solution. The method demonstrated sensitivity, precision, and accuracy enough for its application in the measurement of basal release of these catecholamines from C. carbonaria aortic rings in vitro. The mean (standard deviation) concentrations of dopamine, noradrenaline, and adrenaline were 3.48 (2.55) ng/mL, 1.40 (0.57) ng/mL, and 1.87 (1.09) ng/mL, respectively.

Accumulation of trace metals in eggs and hatchlings of Chelonia mydas.

BACKGROUND: The objective of this study was to verify the accumulation of trace metals in eggs and hatchlings of Chelonia mydas, evaluating if metal accumulation is originated from maternal transfer and/or from the incubation environment. Other assessments were also performed, as metal distribution in different tissues (blood, kidney, liver, muscle, and turtle shells) of newly hatched turtles, and genotoxic analysis, to verify possible damages caused by the presence of metals. METHODS: The assessments were carried out by quantifying Cd, Ni, Pb, Mn and Fe in egg sample collected during laying time (eggshells (ELT) and egg content (EC)), eggshells from newly hatched turtles (ENH), hatchlings tissues (H - blood, kidney, liver, muscle, and shell)) (n = 18 for each biological sample - 3 of each nest) and nest sediments (n = 6, one of each nest). Comparative analysis were made between ELT and ENH, as well as between egg content (EC) and the sum of tissue samples from hatchlings, using Mann-Whitney hypothesis test (p < 0,05). The amount of metals in different hatchling was quantified and followed by the Dunn post-test. A principal component analysis (PCA) was also employed. RESULTS: Metals studied were found in all investigated samples. The concentration of a great amount of investigated metals was significantly higher (P=<0.001) in eggshells from ENH than in ELT. An increase in Cd (2.16-fold), Pb (3.47-fold), Fe (6.83-fold) and Mn (195.57-fold) concentration was noticed in ENH. We also observed an increase in Fe (1.59-fold), Mn (1.74-fold) and Ni (1.59-fold) concentration in hatchling, when compared with EC, due to transfer from nest sediments. In relation to the hatchling's tissues, blood was shown to accumulate higher concentrations of Ni and Pb, while shells accumulated more Cd and Fe, and Mn is more associated with liver and kidney. Fe was the highest accumulated metal in both tissues, and muscles presented discrete concentrations of Ni, Mn, and Pb. A mean concentration of 1.25‰ MN was obtained in C. mydas hatchlings, indicating that the accumulation of metals in hatchlings didn't cause toxicology effects. CONCLUSION: Hatchlings accumulate metals through the maternal and sediment transfer, although the levels of metal accumulation were not enough to cause genotoxic damage.

Do prolonged fasting periods influence the postprandial metabolic responses in turtles? What can Trachemys scripta elegans teach us about this?

The postprandial period is characterized by a modification of the gastrointestinal activity after food intake, accompanied by an increase in metabolic rate, secretion of acids, and absorption of nutrients. For ectothermic vertebrates, those changes are particularly prominent given the relatively low metabolic cost and the low frequency of food uptake. However, prolonged fasting periods decrease energy reserves and may compromise the upregulation of costly processes, such as the increase in metabolic rate after resuming the meal intake. Assuming that the main source of energy needed to support such events is provided from the animal's own body reserves, our aim with this study is to test the hypothesis that the longer the period of fasting, the smaller the metabolic rate increase during the postprandial period, since lesser energy reserves trigger these increases. For this, we measured the oxygen consumption rates (V̇O2 ) of red-eared slider turtles, Trachemys scripta elegans, submitted to different periods of fasting (47 and 102 days), before and after the ingestion of meals equivalent to 5% of their body masses. Despite the longer fasting period, which led to a reduction of 10.77% in the body mass of the turtles, there were no differences between the two experimental groups regarding maximum V̇O2 values after food intake (V̇O2 peak), postprandial metabolic scope, mean time to V̇O2 peak, and postprandial duration. Results indicate that 102 fasting days does not compromise aerobic metabolic increase during postprandial period and does not impair digestive process of the turtles, even with a loss of body mass.

Venous blood gas and biochemical analysis of wild captured green turtles (Chelonia mydas) and Kemp's ridley turtles (Lepidochelys kempii) from the Gulf of Mexico.

Blood was collected from wild captured green and Kemp's ridley turtles off the west coast of Florida, USA. Blood gases and biochemical values were analyzed using a point of care (POC) device in the field. Analytes include pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess (BE), oxygen saturation (sO2), lactate, sodium (Na), potassium (K), chloride (Cl), total carbon dioxide (TCO2), anion gap, ionized calcium, glucose, blood urea nitrogen (BUN), creatinine (Crea), hematocrit (Hct), and hemoglobin (Hb). These are novel data for wild healthy Kemp's ridley turtles, and results for green turtles were generally consistent with past studies of green turtles with exceptions primarily in blood gas values. Ninety percent of the green turtles had fibropapillomatosis (FP), but none of the blood analytes were correlated with disease severity. Only BUN was correlated with weight of green turtles, and there was no correlation between blood parameters and weight of Kemp's ridley turtles. This study provides data that are useful in understanding the physiologic status of sea turtles specific to this region, allowing for comparisons to other populations, life stages, and disease states.

Accumulation of trace elements in leatherback turtle (Dermochelys coriacea) eggs from the south-western Caribbean indicates potential health risks to consumers.

Trace metal and metalloid levels were measured in eggs of the NW Atlantic leatherback turtle (Dermochelys coriacea) from nesting grounds in the Bocas del Toro province, Panama, to infer exposure and associated risks to local communities. Samples were analyzed for a set of 26 essential and non-essential elements using inductively coupled plasma techniques. Median concentrations of Fe, Zn, As, Se and Sr in D. coriacea eggs were higher than previously reported for this species, which likely reflects differential contamination levels of specimens during foraging. The evaluation of non-carcinogenic human health risks from ingesting leatherback eggs has revealed potential deleterious effects due to high concentrations of As, Se and Sr for all examined age and gender groups, while Hg and Zn levels were above international standards for children. Hazard index (HI) values exceeded unity in all cases indicating serious health impacts related to possible additive effects of multiple metals co-occurring in the eggs. Our findings suggest that exposure to high (inorganic) As and Cr(VI) levels is associated with an increased carcinogenic risk, significantly exceeding the acceptable lifetime risk of 10-6 for both adults and children. Despite some limitations, such as unclear As and Cr speciation, our results demonstrated that the ingestion of D. coriacea eggs poses considerable health risks to local communities, and their consumption should not exceed 3.4 × 10-4 g (5.0 × 10-6 eggs) kg BW d-1. Resource managers and conservationists should focus their attention to human health effects as an alternative tool to address egg poaching and consumption.

Ingestion of plastic marine litter by sea turtles in southern Brazil: abundance, characteristics and potential selectivity.

The ingestion of plastic marine litter (PML) by sea turtles is widespread and concerning, and the five species that occur in the southwestern Atlantic - green, loggerhead, olive ridley, leatherback and hawksbill - are vulnerable to this pollution. Here, we quantified and characterized PML ingested by these species in southern Brazil, and observed PML ingestion in 49 of 86 sampled individuals (~57.0%). Green turtles presented the highest rates and variety of ingested plastics, and such ingestion has been high at least since 1997. Omnivorous turtles presented higher PML ingestion than carnivorous ones. Loggerheads displayed a negative correlation between body size and number of ingested items. Green turtles ingested mostly flexible transparent and flexible/hard white plastics; loggerheads ate mainly flexible, hard and foam fragments, in white and black/brown colors. These results help us better understand PML ingestion by sea turtles, highlighting the seriousness of this threat and providing information for prevention and mitigation strategies.

Scavenging as a pathway for plastic ingestion by marine animals.

Plastic pollution is prevalent worldwide and affects marine wildlife from urbanized beaches to pristine oceanic islands. However, the ecological basis and mechanisms that result in marine animal ingestion of plastic debris are still relatively unknown, despite recent advances. We investigated the relationship between scavenging behavior and plastic ingestion using green turtles, Chelonia mydas, as a model. Diet analysis of C. mydas showed that sea turtles engaging in scavenging behavior ingested significantly more plastic debris than individuals that did not engage in this foraging strategy. We argue that opportunistic scavenging behavior, an adaptive behavior in most marine ecosystems, may now pose a threat to a variety of marine animals due to the current widespread plastic pollution found in oceans.

Characterization of spermatogonial cells and niche in the scorpion mud turtle (Kinosternon scorpioides).

Undifferentiated spermatogonia (Aund) or spermatogonial stem cells (SSCs) are committed to the establishment and maintenance of spermatogenesis and fertility throughout a male's life and are located in a highly specialized microenvironment called niche that regulates their fate. Although several studies have been developed on SSCs in mammalian testis, little is known about other vertebrate classes. The present study is the first to perform a more detailed investigation on the spermatogonial cells and their niche in a reptilian species. Thus, we characterized Aund/SSCs and evaluated the existence of SSCs niche in the Kinosternon scorpioides, a freshwater turtle found from Mexico to northern and central South America. Our results showed that, in this species, Aund/SSCs exhibited a nuclear morphological pattern similar to those described for other mammalian species already investigated. However, in comparison to other spermatogonial cell types, Aund/SSCs presented the largest nuclear volume in this turtle. Similar to some mammalian and fish species investigated, both GFRA1 and CSF1 receptors were expressed in Aund/SSCs in K. scorpioides. Also, as K. scorpioides Aund/SSCs were preferentially located near blood vessels, it can be suggested that this niche characteristic is a well conserved feature during evolution. Besides being valuable for comparative reproductive biology, our findings represent an important step towards the understanding of SSCs biology and the development of valuable systems/tools for SSCs culture and cryopreservation in turtles. Moreover, we expect that the above-mentioned results will be useful for reproductive biotechnologies as well as for governmental programs aiming at reptilian species conservation.

Trace elements influence the hatching success and emergence of Caretta caretta and Chelonia mydas.

Trace elements from industrial, domestic and agricultural activities can be transferred into marine environments, affecting the survival of sea species. Due to their global distribution, sea turtles are recognized as indicators of ocean pollution. The aim of this work was to quantify Ba, Cd, Cr, Cu, Fe, Mn, Pb, Sr and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) in the eggs and offspring of Caretta caretta and Chelonia mydas from two important nesting beaches, Guanabara Beach, Anchieta, and Trindade/Martim Vaz Island, Espírito Santo, Brazil. C. mydas pups and eggs collected on Trindade/Martim Vaz Island presented significant differences in Ba, Cr, Cu, Mn and Sr (p < 0.001). Higher concentrations of Ba, Pb, and Sr were detected in eggs of this species in comparison to those of C. caretta on Guanabara Beach, Anchieta. Ba and Cd presented higher concentrations in pups than in eggs of C. caretta, which could indicate nesting pollution. Positive correlations between trace element concentrations and hatching success in C. caretta nests from Guanabara Beach, Anchieta, could be identified for Cu and Zn (r²â€¯= 0.86, F2.7 = 21, p < 0.001). Emergence success was influenced by Cu and Cd (r²â€¯= 0.84, F2.7 = 18.9, p = 0.002). In addition, Ba and Cd also influenced the emergence sucess (r²â€¯= 0.56, F2, 10 = 6.29, p = 0.017). The hatching success of C. mydas was influenced by the concentration of Cu (r²â€¯= 0.53, F2.14 = 7.82, p = 0.005). Further studies including the analyzed areas and migratory routes should be performed to promote conservation management at these beaches.

Convective oxygen transport during development in embryos of the snapping turtle Chelydra serpentina.

This study investigated the maturation of convective oxygen transport in embryos of the snapping turtle (Chelydra serpentina). Measurements included: mass, oxygen consumption (V̇O2 ), heart rate, blood oxygen content and affinity and blood flow distribution at 50%, 70% and 90% of the incubation period. Body mass increased exponentially, paralleled by increased cardiac mass and metabolic rate. Heart rate was constant from 50% to 70% incubation but was significantly reduced at 90% incubation. Hematocrit and hemoglobin concentration were constant at the three points of development studied but arteriovenous difference doubled from 50% to 90% incubation. Oxygen affinity was lower for the early 50% incubation group (stage 19) compared with all other age groups. Blood flow was directed predominantly to the embryo but was highest to the chorioallantoic membrane (CAM) at 70% incubation and was directed away from the yolk as it was depleted at 90% incubation. The findings indicate that the plateau or reduction in egg V̇O2  characteristic of the late incubation period of turtle embryos may be related to an overall reduction in mass-specific V̇O2  that is correlated with decreasing relative heart mass and plateaued CAM blood flow. Importantly, if the blood properties remain unchanged prior to hatching, as they did during the incubation period studied in the current investigation, this could account for the pattern of V̇O2 previously reported for embryonic snapping turtles prior to hatching.