Polycyclic aromatic hydrocarbons (PAHs) and some biomarkers in the green sea turtles (Chelonia mydas)

Selected blood biochemical parameters (Glutathione S transferase: GST; Alanine aminotransferase: ALT; Aspartate aminotransferase: AST; Lactate dehydrogenase: LD and glucose) and polycyclic aromatic hydrocarbons (PAHs) were measured in blood samples from 18 green sea turtles (Chelonia mydas) from the Iranian coastline on the northern shore of the Sea of Oman. Mean total PAH concentration in the blood samples was 17.802 ± 1.006 ng/gdw. The study found no significant correlation between blood biochemical parameters and PAHs (p > 0.01), however significant correlations were found between total PAHs and GST activity (p < 0.01). The GST activity measured in this study was useful as a first investigation into the biological effects of PAH pollution as well as in determining the bioavailability of pollution. The results suggest that PAHs might be a factor influencing a reduction in green sea turtle egg fertilization and hatching success. Further study is needed concerning the effects of PAHs and other pollutants on green sea turtles, and specifically on the potential impact on the fetal development of green sea turtles.

Tools for non-invasive sampling of metal accumulation and its effects in Mediterranean pond turtle populations inhabiting mining areas

Among reptiles, freshwater turtle species have high potential for metal accumulation because of their long lifespan or their aquatic and terrestrial habits. In order to monitor metal bioaccumulation, determine potential toxic effects, and investigate tools for non-invasive metal sampling in reptiles, we studied lead (Pb) and mercury (Hg) accumulation in Mediterranean pond turtles (Mauremys leprosa) inhabiting two former mining areas, one of them with high environmental concentrations of Pb (Sierra Madrona-Alcudia Valley district) and the other one with high environmental concentrations of Hg (Almadén district). Individuals from the Pb mining area showed mean blood concentrations (i.e. 5.59 μg Pb/g dry weight, d.w.) that were higher than those measured in other populations. Blood Hg concentrations were highest (8.83 μg Hg/g d.w.) in the site close to the former Hg mines, whereas blood Hg concentrations in terrapins from another site of Almadén district, located ∼28 km downstream, were not different from locations at the non-mining area. Animals from the Pb-contaminated site showed evidence of oxidative stress, whereas those from the Hg-contaminated site showed increased activity of the antioxidant enzyme glutathione peroxidase, as well as reduced circulating levels of the main endogenous antioxidant peptide, glutathione. Concentrations measured in feces and carapace scutes were useful indicators to monitor blood concentrations of Pb, but not of Hg. Our results provide evidence of the usefulness of freshwater turtles as sentinels of chronic metal pollution, and validate non-invasive tools to advance Pb monitoring in reptiles.

Diversity, immunoregulatory action and structure-activity relationship of green sea turtle cathelicidins

Cathelicidins are a family of gene-encoded immune effectors in vertebrate innate immunity. Here, we reported the diversity and biological activity of cathelicidins in green sea turtle, a marine reptile species known for long lifespan and disease resistance. Four novel cathelicidins (Cm-CATH1-4) were identified from green sea turtle. All of them, especially Cm-CATH2, exhibited potent, broad-spectrum and rapid bactericidal and anti-biofilm activities by inducing the disruption of cell membrane integrity. Additionally, Cm-CATH2 effectively induced the macrophages/monocytes and neutrophils trafficking to the infection site, and inhibited the LPS-induced production of inflammatory cytokines, by blocking TLR4/MD2 complex and the downstream signaling pathway activation. In mouse peritonitis and pneumonia models, Cm-CATH2 exhibited evident protection against drug-resistant bacterial infections. Taken together, the diverse structures and functions of Cm-CATHs indicated their pleiotropic role in innate immunity of green sea turtle, and the potent antimicrobial, anti-biofilm and immunomodulatory properties make them ideal candidates for the development of novel anti-infective drugs.

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.

Trace metals in green sea turtles (Chelonia mydas) inhabiting two southern California coastal estuaries

Foraging aggregations of east Pacific green sea turtles (Chelonia mydas) inhabit the Seal Beach National Wildlife Refuge (SBNWR) and San Diego Bay (SDB), two habitats in southern California, USA, located near urbanized areas. Both juvenile and adult green turtles forage in these areas and exhibit high site fidelity, which potentially exposes green turtles to anthropogenic contaminants. We assessed 21 trace metals (TM) bioaccumulated in green turtle scute and red blood cell (RBC) samples collected from SBNWR (n = 16 turtles) and SDB (n = 20 turtles) using acid digestion and inductively coupled plasma mass spectrometry. Principal component analyses of TM composition indicate that SBNWR and SDB turtles have location-specific contaminant signatures, characterized by differences in cadmium and selenium concentrations: SBNWR turtles had significantly more cadmium and selenium in RBC and more selenium in scute samples, than SDB turtles. Cadmium and selenium concentrations in RBC had a strong positive relationship, regardless of location. SBNWR turtles had higher selenium in RBCs than previously measured in other green turtle populations globally. Due to different retention times in blood vs. scute, these results suggest that SBNWR turtles have high long- and short-term selenium exposure. Turtles from SBNWR and SDB had higher trace metal concentrations than documented in green turtle populations that inhabit non-urbanized areas, supporting the hypothesis that coastal cities can increase trace metal exposure to local green turtles. Our study finds evidence that green turtle TM concentrations can differ between urbanized habitats and that long-term monitoring of these green turtles may be necessary.

Evaluating internal exposure of sea turtles as model species for identifying regional chemical threats in nearshore habitats of the Great Barrier Reef

Marine megafauna that forage in proximity to land can be exposed to a diverse mixture of chemicals that - individually or combined - have the potential to affect their health. Characterizing such complex exposure and examining associations with health still poses considerable challenges. The present study summarizes the development and application of novel approaches to identifying chemical hazards and their potential impacts on the health of coastal wildlife, using green sea turtles as model species. We used an epidemiological study approach to collect blood and keratinized scute samples from free-ranging turtles foraging in nearshore areas and an offshore control site. These were analyzed using a combination of non-targeted, effect-based and multi-chemical analytical screening approaches to assess internal exposure to a wide range of chemicals. The screening phase identified a suite of elements (essential and non-essential) as priority for further investigation. Many of these elements are not commonly analyzed in marine wildlife, illustrating that comprehensive screening is important where exposure is unknown or uncertain. In particular, cobalt was present at highly elevated concentrations, in the order of those known to elicit acute effects across other vertebrate species. Several trace elements, including cobalt, were correlated with clinical indicators of impaired turtle health. In addition, biomarkers of oxidative stress (e.g. 3-indolepropionic acid and lipid peroxidation products) identified in the blood of turtles showed significant correlations with clinical health markers (particularly alkaline phosphatase and total bilirubin), as well as with cobalt. To assist interpretation of trace element blood data in the absence of sufficient information on reptile toxicity, we established exposure reference intervals using a healthy control population. In addition, trace element exposure history was investigated by establishing temporal exposure indices using steady-state relationships between blood and scute. Overall, the data provide a strong argument for the notion that trace element exposure is having an impact on the health of coastal sea turtle populations.

Integrated chemical exposure assessment of coastal green turtle foraging grounds on the Great Barrier Reef

The Great Barrier Reef receives run-off from 424,000 km² catchment area across coastal Queensland, incorporating diffuse agricultural run-off, and run-off point sources of land-based chemical pollutants from urban and industrial development. Marine biota, such as green turtles (Chelonia mydas), are exposed to these diverse chemical mixtures in their natural environments, and the long term effects on turtle and ecosystem health remain unknown. This study was part of a larger multi-disciplinary project characterising anthropogenic chemical exposures from the marine environment and turtle health. The aim of this study was to screen for a wide range of anthropogenic chemical pollutants present in the external and internal environment of green turtles, using a combination of traditional targeted chemical analyses, non-target suspect screening, and effect-based bioassay methods, while employing a case-control study design. A combination of passive (water) and grab (water, sediment) samples were investigated. Three known green turtle foraging sites were selected for sampling: two coastal 'case' sites influenced primarily by urban/industrial and agricultural activities, respectively; and a remote, offshore 'control' site. Water and sediment samples from each of the three sampling locations showed differences in chemical pollutant profiles that reflected the dominant land uses in the adjacent catchment. Targeted mass spectrometric analysis for a range of pesticides, industrial chemicals, pharmaceuticals and personal care products found the greatest detection frequency and highest concentrations in coastal samples, compared to the control. Non-target screening analysis of water showed clear differentiation in chemical profile of the urban/industrial site. In-vitro assays of sediment samples from the control site had lowest induction, compared to coastal locations, as expected. Here we present evidence that turtles foraging in coastal areas are exposed to a range of anthropogenic pollutants derived from the adjacent coastal catchment areas.

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

Undifferentiated spermatogonia (A_und) 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 A_und/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, A_und/SSCs exhibited a nuclear morphological pattern similar to those described for other mammalian species already investigated. However, in comparison to other spermatogonial cell types, A_und/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 A_und/SSCs in K. scorpioides. Also, as K. scorpioides A_und/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.

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.

Metabolic adaptations during extreme anoxia in the turtle heart and their implications for ischemia-reperfusion injury

ATP depletion and succinate accumulation during ischemia lead to oxidative damage to mammalian organs upon reperfusion. In contrast, freshwater turtles survive weeks of anoxia at low temperatures without suffering from oxidative damage upon reoxygenation, but the mechanisms are unclear. To determine how turtles survive prolonged anoxia, we measured ~80 metabolites in hearts from cold-acclimated (5 °C) turtles exposed to 9 days anoxia and compared the results with those for normoxic turtles (25 °C) and mouse hearts exposed to 30 min of ischemia. In turtles, ATP and ADP decreased to new steady-state levels during fasting and cold-acclimation and further with anoxia, but disappeared within 30 min of ischemia in mouse hearts. High NADH/NAD+ ratios were associated with succinate accumulation in both anoxic turtles and ischemic mouse hearts. However, succinate concentrations and succinate/fumarate ratios were lower in turtle than in mouse heart, limiting the driving force for production of reactive oxygen species (ROS) upon reoxygenation in turtles. Furthermore, we show production of ROS from succinate is prevented by re-synthesis of ATP from ADP. Thus, maintenance of an ATP/ADP pool and low succinate accumulation likely protects turtle hearts from anoxia/reoxygenation injury and suggests metabolic interventions as a therapeutic approach to limit ischemia/reperfusion injury in mammals.

The role of Virus "X" (Tortoise Picornavirus) in kidney disease and shell weakness syndrome in European tortoise species determined by experimental infection

Tortoise Picornavirus (ToPV) commonly known as Virus "X" was recently discovered in juvenile European tortoises suffering from soft carapace and plastron as well as kidney disease. Therefore, this virus was a potential candidate to be a causative agent for these disease patterns. Spur thighed tortoises (Testudo graeca) seemed to be more susceptible to establish clinical symptoms than other European species like T. hermanni. Thus this trial investigated the role of ToPV in the described syndrome. Two groups of juvenile European tortoises (T. graeca and T.hermanni) each of 10 animals, were cloacally, oronasally and intracoelomically inoculated with an infectious dose (~ 2000 TICD) of a ToPV strain isolated from a diseased T. graeca. A control group of two animals of each species received non-infected cell culture supernatant. The tortoises were examined daily and pharyngeal and cloacal swabs for detection of ToPV-RNA by RT-PCR were taken from each animal every six days for a period of 6 months. At the end of the study the remaining animals were euthanised and dissected. Bacteriological and parasitological tests were performed and organ samples of all tortoises were investigated by RT-PCR for the presence of ToPV and histopathology. Animals that were euthanised at the end of the experiment, were examined for presence of specific anti-ToPV antibodies. Several animals in both inoculated groups showed retarded growth and a light shell weakness, in comparison to the control animals. Three animals were euthanised during the trial, showing reduced weight gain, retarded growth, severe shell weakness and apathy, in parallel to clinical observations in naturally infected animals. In all inoculated animals of both species an intermittent virus shedding, starting from 18 days post inoculation (d.p.i.), till 164 d.p.i. was detected, while the control animals remained negative. The virus was successfully reisolated in terrapene heart cell culture in 16 of 20 inoculated animals of both species. Histopathology of most inoculated animals revealed a lack of bone remodeling and vacuolisation in kidney tubuli which supports the described pathogenesis of nephropathy and osteodystrophy. Anti- ToPV antibody titres ranged from 1:2 to >1:256 in 13 of 20 animals, whereas all control animals were seronegative. The study proofed the Henle Koch`s postulates of ToPV as causative agent for shell dystrophy and kidney disease in both testudo species. The proposed species specific sensitivity towards clinical disease was not observed.

Elucidating temporal trends in trace element exposure of green turtles (Chelonia mydas) using the toxicokinetic differences of blood and scute samples

Blood is considered a suitable biomonitoring matrix for evaluating relatively recent exposure to environmental contaminants since abrupt changes in exposure regimes are rapidly reflected in blood. On the other hand, keratinized tissues, such as turtle scutes, are known to integrate trace element exposure over relatively long time periods. This study aimed to test the use of the differences in blood and scute to inform on the historical trace element exposure of green turtles. We propose a blood-scute kinetic model to predict how an increase in exposure would affect the concentrations in these two matrices over time. We then tested the relationship between blood and scute concentrations for 19 trace elements in two green turtle populations presumed to experience relatively constant exposure conditions. Significant log-log and linear correlations were observed between blood and scute concentrations for Co, As, Mo, Sb, and Cd. We then analysed blood-scute ratios in turtles from two coastal sites with known elevated exposure to various trace elements from previous studies. Deviations from the steady-state were clearly evident in these coastal turtles (for Co and Cd) and were consistent with the model prediction of changes in exposure. These field data provide evidence that blood-scute ratios can provide a valuable tool for examining the historical trace element exposure of turtles. We further present a method by which the general model may be refined and validated, by using data from individual turtles that had been recaptured across multiple years. Although the timeframe and number of recaptured samples available for this study were limited, the temporal changes in blood-scute ratios in these animals were generally consistent with those suggested by the model. Thus, the ratio between paired blood and scute trace element concentrations could be used to establish a temporal exposure index in turtles.

LIPOPHAGY: a novel form of steroidogenic activity within the LEYDIG cell during the reproductive cycle of turtle

BACKGROUND

Steroidogenesis is an indispensable process that is indirectly associated with spermatogenesis in the Leydig cell (LC) to utilize the lipid droplets (LDs) that are critical to maintaining normal testosterone synthesis. The regulation of LD mobilization, known as lipophagy, in the LC is still largely unknown.

METHOD

In the present study, the LC of the Chinese soft-shelled turtle was investigated to identify the steroidogenic activity and lipophagy during the annual reproductive cycle by light microscopy, immunohistochemistry (IHC), immunofluorescence (IF), and transmission electron microscopy (TEM).

RESULTS

The LC showed a dynamic steroidogenic function with strong activity of 3β-HSD, vimentin and tubular ER during hibernation by IHC and TEM. The tubulo-vesicular ER had a weak immunopositive reaction for 3β-HSD in the LC during reproductive phase, suggesting persistent steroidogenic activity. ORO staining and TEM demonstrated that a larger number of LDs had accumulated in the LC during hibernation than in the reproductive phase. These LDs existed in close association with mitochondria and lysosomes by being dynamically surrounded by intermediate filaments to facilitate LD utilization. Lysosomes were found directly attached to large LDs, forming an autophagic tube and engulfing LDs, suggesting that micro-lipophagy occurs during hibernation. Furthermore, the IHC of ATG7 (Autophagy Related Gene 7) and the IF of the LC3 (Microtubule-associated protein light chain 3), p62 (Sequestosome-1 (SQSTM1) and LAMP1(Lysosomal-associated membrane protein 1) results demonstrated strong expression, and further confirmation by TEM showed the existence of an autophagosome and an autolysosome and their fusion during the hibernation season.

CONCLUSION

In conclusion, the present study provides clear evidence of LD consumption in the LC by lipophagy, lysosome and mitochondria during the hibernation period, which is a key aspect of steroidogenesis in the Chinese soft-shelled turtle.

Primary green turtle (Chelonia mydas) skin fibroblasts as an in vitro model for assessing genotoxicity and oxidative stress

Little is known about the effects of contaminants that accumulate in sea turtles. When in vivo exposure studies have ethical and logistical barriers, as is the case with sea turtles, in vitro tools can provide important information on the effects of contaminants. Several in vitro studies have assessed cytotoxicity of contaminants to sea turtles cells, however to gain a more refined mechanistic understanding of the effects of contaminants, sub-lethal effects also require investigation. Considering the complex mixture of contaminants that sea turtles are potentially exposed to, high throughput testing methods are necessary so that a large number of contaminants (and mixtures) can be rapidly tested. This study examined oxidative stress (reactive oxygen species production) and genotoxicity (micronucleus formation) in primary green turtle skin fibroblasts in response to 16 organic and inorganic contaminants found in coastal environments. Significant induction of oxidative stress was found with Cu, Co, Cr, and Hg. Significant effects on genotoxicity were found with Cu, Co, Cr, Hg, Pb and metolachlor. Effect concentrations from the bioassays were used in a simple risk assessment of turtles worldwide using accumulation values from the literature to identify populations at risk. Cu, Co, Cr and Hg were identified as posing the biggest threat to sea turtles. This study demonstrated the validity of using primary turtle cell cultures in the assessment of risk associated with a large number of contaminants using a high-throughput toxicity testing format.

Perfluoroalkyl substances in diamondback terrapins (Malaclemys terrapin) in coastal South Carolina

This study focused on an estuarine wildlife species exhibiting high site fidelity and ubiquitous distribution in coastal environments along the Atlantic and Gulf coasts of the United States to monitor per- and polyfluoroalkyl substances (PFAS). A total of 75 diamondback terrapin (Malaclemys terrapin) plasma samples were collected from five creeks associated with Kiawah (Oyster Creek, Fiddler Creek, Sandy Creek, Gnat Creek) and Edisto (Townsend Creek) islands in Charleston County, South Carolina and investigated for 15 legacy PFAS. Of those, PFHxS was the only PFAS found in all terrapin plasma samples. Four additional PFAS were routinely detected (greater than 90% of the samples) and were included in statistical analyses: PFOS, PFNA, PFDA, and PFUnA. Sex-differences were observed for two creeks with male plasma containing higher PFAS than female plasma (PFHxS at Townsend Creek, PFOS at Oyster Creek). Sex-specific site differences in PFAS concentrations were observed primarily for males, suggesting male terrapins may be more sensitive indicators of localized contaminant profiles than females. Three PFAS were observed to have negative correlations with body mass: PFOS in males (p = 0.045, tau = -0.220), PFNA in males (p = 0.016, tau = -0.269), and PFHxS in both males (p = 0.007, tau = -0.302) and females (p = 0.001, tau = -0.379). No relationships for body mass and PFDA and PFUnA were observed.

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 (r² = 0.86, F2.7 = 21, p < 0.001). Emergence success was influenced by Cu and Cd (r² = 0.84, F2.7 = 18.9, p = 0.002). In addition, Ba and Cd also influenced the emergence sucess (r² = 0.56, F2, 10 = 6.29, p = 0.017). The hatching success of C. mydas was influenced by the concentration of Cu (r² = 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.

Relationship between plasma biochemistry values and metal concentrations in nesting olive ridley sea turtles

A hundred nesting olive ridley turtles were sampled to determine biochemical parameters (ALP, AST, ALT, creatinine, albumin, cholesterol, glucose, proteins, triglycerides, urea, and P-nitrophenyl acetate esterase activity). Esterase activity (EA) is a new biomarker very sensitive to metals. Most of the samples showed detectable levels. We also analyzed the concentration of 11 inorganic elements (As, Cd, Cr, Cu, Mn, Ni, Pb, Sr, Ti, Se, and Zn), some of them previously reported with very high concentrations in this population (especially cadmium with 82 and 150 μg g^-1 ww in liver and kidney, respectively). Cadmium presented two negative relationships with creatinine and glucose. Some other understudied elements, Sr and Ti, for instance, presented five and four significant relationships with some biochemical parameters, respectively (most of them positive). EA was the parameter with most negative relationships (with Pb, Ti, As, Cr, and Se), reinforcing the results of other researchers in humans regarding the possible inhibition of EA by metals.

Coal combustion residues and their effects on trace element accumulation and health indices of eastern mud turtles (Kinosternon subrubrum)

Coal combustion is a major energy source in the US. The solid waste product of coal combustion, coal combustion residue (CCR), contains potentially toxic trace elements. Before 1980, the US primarily disposed of CCR in aquatic settling basins. Animals use these basins as habitat and can be exposed to CCR, potentially affecting their physiology. To investigate the effects of CCR on eastern mud turtles (Kinosternon subrubrum), we sampled 30 turtles exposed to CCRs and 17 unexposed turtles captured in 2015-2016 from the Savannah River Site (Aiken, SC, USA). For captured turtles, we (1) quantified accumulation of CCR in claw and blood samples, (2) used bacterial killing assays to assess influences of CCR on immune responses, (3) compared hemogregarine parasite loads, and (4) compared metabolic rates via flow-through respirometry between CCR-exposed and unexposed turtles when increased temperature was introduced as an added stressor. Turtles exposed to CCR accumulated CCR-associated trace elements, corroborating previous studies. Blood Se and Sr levels and claw As, Se, and Sr levels were significantly higher in turtles from contaminated sites. Average bacterial killing efficiency was not significantly different between groups. Neither prevalence nor average parasite load significantly differed between CCR-exposed and reference turtles, although parasite load increased with turtle size. Regardless of site, temperature had a significant impact on turtle metabolic rates; as temperature increased, turtle metabolic rates increased. The effect of temperature on turtle metabolic rates was less pronounced for CCR-exposed turtles, which resulted in CCR-exposed turtles having lower metabolic rates than reference turtles at 30 and 35 °C. Our results demonstrate that turtles accumulate CCR from their environment and that accumulation of CCR is associated with changes in turtle physiological functions when additional stressors are present.

Evidence of embryonic regulation of maternally derived yolk corticosterone

In recent years, the potential for maternal stress effects to adaptively alter offspring phenotype has received considerable attention. This research has identified offspring traits that are labile in response to maternal stress; however, an understanding of the mechanisms underlying these effects is lagging and is crucial to appreciating the significance of this maternal effect. In the present study, we sought to better understand maternal stress effects by examining the potential for embryonic regulation of corticosterone exposure, determining the phenotypic consequences of elevated corticosterone during development, and characterizing the levels of maternally transferred corticosterone in unmanipulated eggs using Trachemys scripta By dosing eggs with tritiated corticosterone and tracking the steroid throughout development, we found that most corticosterone is metabolized, and less than 1% of the corticosterone dose reaches the embryo as free corticosterone. We also found that exogenous dosing of corticosterone, in concentrations sufficient to overwhelm embryonic metabolism, reduces embryonic survival and negatively impacts hatchling traits important to fitness. Our results demonstrate that concentrations of maternal corticosterone in the yolks of unmanipulated eggs are low and are significantly lower than the doses of corticosterone required to elicit phenotypic effects in hatchlings. Taken together, these results provide evidence that both the embryo and the female may minimize corticosterone accumulation in the embryo to avoid reductions in embryonic survival and negative impacts on offspring phenotype and fitness.

Mercury Contamination in Diamondback Terrapins in New Jersey

Mercury contamination in consumed foods poses a significant threat to human health globally. The consumption of mercury-contaminated turtle meat is of special concern due to mercury's capability to bioaccumulate and biomagnify in organisms. Turtles are long-lived predators, allowing for a high degree of bioaccumulation and biomagnification of contaminants. In the U.S., diamondback terrapins (Malaclemys terrapin) are legally harvested in several states throughout their range. Harvested turtles are usually sold to both local and global markets mainly for human consumption, which results in a human consumption threat. The objective of this study was to analyze mercury concentrations to determine if the consumption of terrapins poses a threat to human health. Diamondback terrapins were collected from two study sites: Cape May and Hackensack Meadowlands, New Jersey, relatively pristine and contaminated estuaries, respectively. Turtle carapace, blood, and muscle samples were analyzed for total mercury concentrations. Results showed significant difference between study sites and females' and males' blood mercury concentrations. Similarly, results showed blood mercury correlated with carapace length. Results also showed that 50% of Cape May muscle samples and 72.7% Meadowlands muscles samples surpassed the New Jersey sensitive threshold of 0.18 ppm. Furthermore, 27.3% of Cape May muscle samples and 45.5% of Meadowlands muscles samples surpassed the U.S. Environmental Protection Agency's mercury threshold of 0.3 ppm for seafood consumption for the general public. Overall, the harvest of terrapins could pose a threat to consumers, and terrapins should be monitored closely or possibly banned for human consumption, especially in areas with known contamination history.

Cadmium in tissues of green turtles (Chelonia mydas): A global perspective for marine biota

Cadmium (Cd) is a metal of toxicological interest because of its potential high toxicity to organisms and ability to biomagnify. Evaluating concentrations of Cd in organisms on a large spatial scale can provide insights to its global distribution. This study examined Cd concentrations in kidney and liver tissues of 137 specimens of green turtles (Chelonia mydas) collected in Australia, Brazil, Hawaii, Japan, and the continental United States (Gulf of Mexico). We used comparative analyses of kidney and liver of 35 individuals, of which seven turtles from each locality belong to the same size class for comparison purposes between their ocean of origin. Cd was detected in all samples, with the highest bioconcentration in kidneys. Specimens originating from the Pacific Ocean had significantly higher mean Cd levels in liver (13.24 μg/g) and kidney (34.17 μg/g) than the specimens collected in the Atlantic Ocean with lower mean values in liver (1.00 μg/g) and kidney (4.04 μg/g). Furthermore, Cd concentrations in turtle tissues were generally greater than concentrations found in other marine organisms, for example dolphins. This result was unexpected because dolphins occupy a higher trophic level than green turtles which are only herbivorous. A possible explanation is a change in feeding habits of green turtles, in which juveniles feed in near shore habitats, potentially resulting in greater Cd accumulation in juveniles compared to adults. This global distribution trend has also been observed in other marine organisms (e.g., insects, birds, and mammals) and indicates that global factors may be more important than regional factors in determining Cd concentrations of marine organisms.

CAPSULE

Global factors are more relevant than local factors in the distribution of cadmium in biota, using green turtle as a sentinel species.

The Role of Acetylcholine in Attention in Turtles (Chrysemys picta)

Research on mammals and turtles has suggested that acetylcholine is involved in attention in these groups. Two experiments investigated the ability of painted turtles (Chrysemys picta) to ignore irrelevant stimuli when the basal forebrain acetylcholine system was compromised. In experiment 1, turtles given lesions of the basal magnocellular cholinergic nucleus (NBM) or sham lesions were tested on a go/no go discrimination between horizontal and vertical stripes with or without irrelevant inserts in the box. The irrelevant inserts were blue and white checked walls and green carpet on the floor. The group with lesions of the NBM and no irrelevant inserts had no difficulty learning the task, but the lesioned group with irrelevant inserts was impaired on the discrimination. The sham-lesioned group was not impaired by the presence of irrelevant inserts. In experiment 2, turtles were given either the acetylcholine muscarinic receptor blocker scopolamine or saline and tested on the same task. The turtles given scopolamine had no difficulty learning the task in the absence of irrelevant inserts, but they were severely impaired when irrelevant inserts were present. The irrelevant inserts did not affect the learning of control turtles given saline. These findings provide evidence that acetylcholine enhances turtles' ability to orient to relevant stimuli and suggest that its role in learning and memory may be to allow animals to orient to the stimuli relevant to a task and to ignore irrelevant stimuli.

First ecotoxicological assessment of Caretta caretta (Linnaeus, 1758) in the Mediterranean Sea using an integrated nondestructive protocol

The loggerhead sea turtle (Caretta caretta) is a long-lived carnivorous reptile included in the IUCN Red List. The IUCN assessment for this species underlines the lack of information regarding pollution and pathogens and indicates as a priority effort to investigate and reduce the impacts of these threats. In this contest, the aim of our study was to conduct the first ecotoxicological assessment of this species in the Mediterranean Sea using a nondestructive integrated methodology. We set up and applied a monitoring protocol which includes endpoints, such as CYP1A, LPO, ENA assay, B esterases, never investigated before in this species. Seventy-five loggerhead turtles were sampled in a nondestructive way in Italian Sea Turtle Rescue Centers or free-ranging along the Spanish coasts. Blood, skin and carapace samples were used to test biomarker responses (CYP1A, VTG, LPO, Comet and ENA assay, BChE, GGT) and contaminant (OCs, PAHs, Pb, Cd, Hg) levels. Elaboration of experimental results was carried out taking also into consideration different age classes of the specimens. Among the main results obtained we should underline the statistically significant correlation between carcinogenic PAHs in blood and DNA fragmentation as well as between Cd in carapace and GGT in plasma. We also evidenced as youngest animals showed significantly higher DNA fragmentations, BChE inhibition and increase of GGT. Older specimens showed the highest levels of erythrocyte nuclear abnormalities which may indicate a long term toxicological stress. This study contributed to expand the knowledge about the ecotoxicology of C. caretta in the Mediterranean. The nondestructive protocol could also be applied to other marine ecosystems and other sea turtle species.

Oxidative stress biomarkers and organochlorine pesticides in nesting female hawksbill turtles Eretmochelys imbricata from Mexican coast (Punta Xen, Mexico)

Because of their vulnerable population status, assessing exposure levels and impacts of toxicants on the health status of Gulf of Mexico marine turtle populations is essential, and this study was aimed to obtain baseline information on oxidative stress indicators in hawksbill sea turtle (Eretmochelys imbricata). In order to evaluate the health status of sea turtles and the effect of organochlorine compounds (OC) in the southern part of the Gulf of Mexico, we searched for relationships between carapace size and the activity of antioxidant enzymes in the blood of the hawksbill sea turtle. The level of oxidative stress biomarkers such as the enzymes catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione S-transferase (GST), and acetylcholinesterase (Ache) in the hawksbill sea turtle was analysed during nesting season in the years 2014-2015 at Punta Xen (Campeche, Mexico). The results of this study provide insight into data of antioxidant enzyme activities in relation to contaminant OCPs in hawksbill sea turtles and the possible health impacts of contaminant in sea turtles.

Assessment of Mercury Concentration in Turtles (Podocnemis unifilis) in the Xingu River Basin, Brazil

Many studies on mercury contamination in aquatic biota deal with the effect of consuming metal-contaminated organisms on human health. In this study, we examined the factors that cause mercury contamination in Podocnemis unifilis in the Xingu River Basin of Mato Grosso and Pará States, Brazil. We quantified by atomic absorption spectroscopy with cold vapor the total mercury (THg) content in the liver and muscle samples of 50 Podocnemis unifilis specimens collected from the basin. The liver and muscle samples contained 134.20 ± 119.30 ng g−1 THg and 24.86 ± 26.36 ng g−1 THg, respectively. Each chelonian or meal has, on average, 5.34× more Hg than the highest level established as acceptable. From the results it can be inferred that, given the weekly consumption of chelonians, the riverine and indigenous communities in the Xingu River Basin are at risk of chronic consumption of Hg in amounts beyond the acceptable limit. The potential high risk to the health of this population is evident; however, the risk classification needs to be further studied.