Influence of a Former Mining Area in the Heavy Metals Concentrations in Blood of Free-Living Mediterranean Pond Turtles (Mauremys leprosa)

Trachemys dorbigni as a metal(loid) bioindicator: a study in rural and urban areas

Metals and metalloids are persistent environmental pollutants with the potential for bioaccumulation, posing significant health risks, including genotoxicity. These contaminants are prevalent in industrial and agricultural runoff. This study utilizes Trachemys dorbigni, an aquatic reptile, as a bioindicator to assess environmental contamination by metals and metalloids in both rural and urban settings in Pelotas, Rio Grande do Sul, Brazil. We captured specimens using pit-type traps with barriers (fyke nets), dividing them into two groups: 15 from a rural area and 15 from an urban area. Each animal underwent physical evaluations, and biometric data (weight, total carapace length and width) were recorded to calculate body condition indices. Biological samples were collected via manual restraint, with blood samples drawn from the supraoccipital venous sinus and linear carapace fragments obtained through manual scraping. Water samples from each location were also analyzed. Using atomic absorption spectrophotometry, concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn were measured in the water, carapace fragments, and blood samples. Cellular damage was assessed through flow cytometry and microscopy, examining erythrocyte disruption, reactive oxygen species, membrane fluidity, DNA fragmentation and micronucleus formation. Urban area samples showed concentrations of As, Cd, Cu, Fe, Hg and Ni exceeding national standards set by the Conselho Nacional do Meio Ambiente (CONAMA), with rural areas also showing elevated levels of As, Cd, Hg and Ni. Biometric analysis revealed that rural reptiles had significantly higher weight and carapace dimensions, whereas urban tortoises displayed a higher body condition index and significantly elevated blood levels of Al, Cr, Ni, Pb and Zn. The urban tortoises also exhibited higher concentrations of all tested metal(loid) in carapace samples (p < 0.05) and more pronounced cellular damage (p < 0.05), highlighting severe bioaccumulation and associated deleterious effects. Elevated reactive oxygen species levels were noted in rural specimens. This study underscores the impact of water degradation and metal(loid) pollution in urban environments on T. dorbigni, suggesting that carapace tissue analysis can serve as a chronic exposure indicator to these harmful contaminants.

HEALTH ASSESSMENT OF SPOTTED (CLEMMYS GUTTATA) AND PAINTED (CHRYSEMYS PICTA) TURTLES IN CAPE COD, MASSACHUSETTS, U.S.A, WITH DETECTION OF A NOVEL ADENOVIRUS

Freshwater turtles face numerous anthropogenic threats worldwide. Health assessments are a key component of chelonian population assessment and monitoring but are under reported in many species. The purpose of this study was to characterize the health of spotted turtles (Clemmys guttata; n = 30) and painted turtles (Chrysemys picta; n = 24) at Camp Edwards, a military base in Cape Cod, Massachusetts, using physical examinations, hematology, plasma heavy metal analyses, and pathogen surveillance via PCR. Spotted turtles had a high prevalence of carapace (n = 27, 90%) and plastron (n = 14, 46.7%) lesions, and a previously undescribed adenovirus was detected in three animals (proposed as Clemmys adenovirus-1). Female painted turtles had lower plasma copper (p = 0.012) and higher strontium (p = 0.0003) than males, and appeared to be in a similar plane of health to previous reports. This initial health assessment effort provides useful baseline data for future comparison in these species. Conservation efforts on Camp Edwards should incorporate continued health surveillance of these populations to identify intervention opportunities and determine the conservation threats, if any, of the novel adenovirus.

Morphological variations and demographic responses of the Mediterranean pond turtle Mauremys leprosa to heterogeneous aquatic habitats

Human activities affect terrestrial and aquatic habitats leading to changes at both individual and population levels in wild animal species. In this study, we investigated the phenotype and demographics of the Mediterranean pond turtle Mauremys leprosa (Schweigger, 1812) in contrasted environments of Southern France: two peri-urban rivers receiving effluents from wastewater treatment plants (WWTP), and another one without sewage treatment plant. Our findings revealed the presence of pesticides and pharmaceuticals in the three rivers of investigation, the highest diversities and concentrations of pollutants being found in the river subsections impacted by WWTP effluents. Principal component analysis and hierarchical clustering identified three levels of habitat quality, with different pollutant concentrations, thermal conditions, nutrient, and organic matter levels. The highest turtle densities, growth rates, and body sizes were estimated in the most disturbed habitats, suggesting potential adult benefits derived from harsh environmental conditions induced by pollution and eutrophication. Conversely, juveniles were the most abundant in the least polluted habitats, suggesting adverse effects of pollution on juvenile survival or adult reproduction. This study suggests that turtles living in polluted habitats may benefit from enhanced growth and body size, at the expense of reproductive success.

Heavy metal concentrations in Caspian pond turtle (Mauremys caspica) in Zarivar International Wetland, Kurdistan Province of Iran

In the present study, the cadmium, lead, and zinc levels in the blood and shell of Caspian pond turtles (Mauremys caspica) were investigated at five stations in Zarivar International Wetland in Kurdistan Province. All specimens were released at their capture locations within 2 h of capture. Water samples were collected at each station. Heavy metal concentrations were determined using an atomic absorption spectrometer. The mean cadmium, lead, and zinc concentrations were 0.04, 32.10, and 11.45 mg/l in blood samples; 1.82, 16.91, and 89.22 mg/l in shell samples; 0.005, 1.30, and 0.07 mg/l in water samples, respectively. In this study, the highest metal adsorption was zinc and was observed in shell. According to the results of this study, the shell of the Caspian Pond Turtle can be used to estimate the concentration of heavy metals. Our results suggest that Caspian pond turtle can be used as a biological indicator to estimate heavy metals.

Reproductive Traits Demonstrate How Well the Mediterranean Stripe-Necked Turtle Mauremys leprosa Can Flourish under Highly Degraded-Polluted Conditions

We measured and compared the reproductive traits of the Mediterranean stripe-necked turtles Mauremys leprosa living in highly degraded-polluted vs. intact natural habitats in Algeria. Data on reproduction were obtained by using X-ray examination of gravid females and examination of nests. The results were opposite to the negative trend confirmed in most freshwater turtles exposed to pollution and suggested the ability of this species to flourish instead in highly degraded-polluted habitats. An optimum development was recorded for several reproductive patterns of the studied freshwater turtle under conditions considered uninhabitable for other vertebrates. Females exhibited record body sizes among conspecifics, which allowed them to carry significantly larger clutches, exceeding by up to 3 eggs the previously largest reported clutch. The mean clutch size (8.79 ± 2.70 eggs) was also higher than findings from previous studies, except for in some other polluted habitats. Furthermore, large females even with large clutches carried large eggs. Egg measurements in the disturbed habitat revealed new records exceeding those previously noted; in egg length (by 3.0 mm), egg width (by 2.8 mm), egg mass (by 1.8 g), and clutch mass (by 18.6 g). In comparison, the usual reproductive performances were observed in the intact natural habitat; female body sizes were significantly smaller and carried fewer eggs of smaller size.

Freshwater aquatic reptiles (Testudines and Crocodylia) as biomonitor models in assessing environmental contamination by inorganic elements and the main analytical techniques used: a review

Despite the general lack of studies that use reptiles as bioindicators, the value of freshwater turtles and crocodilians in ecotoxicology has been proven, due to their importance as sentinel species. The aim of this study was to compile information on the use of freshwater turtles and crocodilians as environmental biomonitors of inorganic element contamination. We searched for articles in databases using specific keywords. A total of 104 studies published between the years 1970 and 2020 were collected. We noted a general increase in the number of studies involving turtles and crocodilians during the study time period. The Order Testudines were the subjects of 46% of the analysed publications, and the Order Crocodylia accounted for 54%. Within these studies, we counted 39 species (turtles n = 29 and crocodilians n = 10). Forty chemical elements were evaluated in the analysed articles, of which the majority represented non-essential elements (Hg, Cd, Pb). Although internal organs constituted the main biological matrix chosen for each group (37%), we observed an increase in the use of non-destructive matrices in both groups (scale, blood, tail muscle, carapace). The majority of analysed studies used HNO₃ for the sample decomposition, with the majority of analyses being performed using atomic absorption spectroscopy (53%). Mainly blank controls (19%), analyte recovery (18%) and replicates (18%) were used as methods of validating analytical procedures. Furthermore, the studies used certified reference materials, which measure the accuracy of the methods used. We conclude that the increase in the use of aquatic reptiles in environmental monitoring research is mainly due to their ability to reveal integrated changes in ecosystems, aiding in environmental public policy decision-making and effective management plans.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Mercury and Organochlorine Pesticides in Tissues of Loggerhead Sea Turtles (Caretta caretta) Stranded Along the Southwestern Mediterranean Coastline (Andalusia, Spain)

Nineteen loggerhead sea turtles (Caretta caretta) stranded along the southwestern Mediterranean coastline (Andalusia) were used in this study. A total of 68 samples of fat (n = 18), liver (n = 15), kidney (n = 13), pectoral muscle (n = 19), and brain (n = 3) were analysed for total mercury (Hg) and organochlorine pesticides [OC: ∑Dichlorodiphenyltrichloroethanes (∑DDT), ∑Hexachlorocyclohexane (∑HCH), ∑Heptachlor, ∑Drins and ∑Endosulfan]. These loggerhead sea turtles showed tissue Hg and OC concentrations similar to or lower than those reported in other studies. Few growth-related variations in Hg or OC levels in relation to straight carapace length were found, probably because the specimens were mostly juveniles. This study will help to fill the gap on spatio-temporal exposure data and ascertain the real world-wide picture of the contamination levels in loggerhead 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.