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Freshwater ecosystems face very strong anthropogenic pressures, among which overexploitation, habitat degradation, flow modification, species invasion, and water pollution lead to growing threats on biodiversity. Urbanization through wastewater treatment, industry through the release of inorganic and organic chemicals, and agriculture through the use of pesticides and herbicides are the main factors involved in water pollution. In France, more precisely in the Pyrenees-Orientales department, the poor quality of the watercourses is attributable overall to the use of glyphosate-based herbicides in agricultural activities. Because these chemicals can impact individuals, populations, and biodiversity, we investigated, under experimental conditions, the physiological response of animals facing abiotic contaminants. We selected as a model, juveniles of the freshwater turtle Trachemys scripta elegans. We measured the gene expression and activity of the catalase and superoxide dismutase enzymes as well as the levels of lipid peroxidation, which are all oxidative stress biomarkers, in turtles challenged with high concentrations of glyphosate-based herbicides, on the one hand, and with degraded waters collected from a local watercourse, on the other. We also measured the acetylcholinesterase activity across the same animals. We showed through variations in gene expression and enzyme activity that a glyphosate commercial formulation induced a stress in turtles. A similar outcome was obtained when turtles faced degraded waters. The results indicated that the poor quality of regional waters could be a real threat for animal health. Because turtles are globally less sensitive to contaminants than amphibians, which are lacking in the degraded waters of the Pyrenees-Orientales department, they could constitute an excellent model to follow the evolution of water quality through the study of oxidative stress biomarkers. Environ Toxicol Chem 2017;9999:1–8. © 2017 SETAC

The red-eared slider turtle, Trachemys scripta elegans, is among the most over-exploited animals and is still exported annually from the USA all over the world. Once introduced into its new environment, feral populations may arise and pose threats to local biodiversity and ecosystem functioning. In France, it is in fact considered as a risk for the Mediterranean pond turtle, Mauremys leprosa, and the European pond turtle, Emys orbicularis, as they may compete for resources and habitat. Freshwater turtles are also host to a variety of parasites including protozoans and helminths. When introduced turtles escape, parasites may spread to native species. The objective of this study was to document the extent of platyhelminth invasions from T. s. elegans to natural M. leprosa populations in northern Spain and southern France and to evaluate the risks that parasite host-switching may pose on indigenous freshwater turtle species. From DNA barcoding analysis based on the sequencing of the Cytochrome c Oxidase I gene, the Bayesian tree and p-distance comparisons of closely related haplotypes revealed a greater polystome richness within M. leprosa than expected, suggesting that host switching may take place in natural environments. Because these parasites most typically infest American turtles like Chrysemys picta marginata and Graptemys pseudogeographica in their natural home range and because parasites were also found within T. s. elegans feral populations, it is suggested that the red-eared slider would serve as a carrier for a variety of not strictly host-specific polystomes that are transmitted to M. leprosa throughout the south of France. The global trade in freshwater turtles thus provides opportunity for parasites to be transported to new destinations which could impact the physiology, behavior and survival of native turtle species.

Increasing anthropogenic activities, like agricultural practices, constitute the main causes of the loss of water quality and disruption of freshwater ecosystems. High concentrations of pesticides, as shown under experimental conditions, can indeed impact freshwater animals. In Southern France, especially in the Pyrénées-Orientales department, because agricultural activities are mainly based on fruit crops and vineyards, glyphosate and AMPA were detected in some watercourses. Thereby we investigated the effects of degraded waters on the physiology of the endemic endangered freshwater species, namely the Mediterranean pond turtle Mauremys leprosa, in contrasted environments along the same rivers on the one hand and between different rivers on the other. We measured the activity and gene expression of two enzymes involved in the oxidative detoxification processes, namely the Catalase and the Superoxide dismutase. We showed significant variations in the Catalase gene expression and activity within turtles of the Fosseille River depending of their location, i.e. upstream or downstream of the wastewater treatment plants (WTP). Because agricultural environments are similar all along this river, they can no be longer considered as the unique source of turtle stress. The processed waters discharged by the WTP, which contribute to watercourses degradation, could therefore considerably impact the biodiversity of the freshwater environments.

International audience; BackgroundPolystomatid flatworms in chelonians are divided into three genera, i.e. Polystomoides Ward, 1917, Polystomoidella Price, 1939 and Neopolystoma Price, 1939, according to the number of haptoral hooks. Among the about 55 polystome species that are known to date from the 327 modern living chelonians, only four species of Polystomoides are currently recognised within the 45 South American freshwater turtles.MethodsDuring 2012, several sites in the vicinity of the cities Cayenne and Kaw in French Guiana were investigated for freshwater turtles. Turtles were collected at six sites and the presence of polystomatid flatworms was assessed from the presence of polystome eggs released by infected specimens.ResultsAmong the three turtle species that were collected, no polystomes were found in the gibba turtle Mesoclemmys gibba (Schweigger, 1812). The spot-legged turtle Rhinoclemmys punctularia (Daudin, 1801) was infected with two species of Neopolystoma Price, 1939, one in the conjunctival sacs and the other in the urinary bladder, while the scorpion mud turtle Kinosternon scorpioides (Linnaeus, 1766) was found to be infected with a single Neopolystoma species in the conjunctival sacs. These parasites could be distinguished from known species of Neopolystoma by a combination of morphological characteristics including body size, number and length of genital spines, shape and size of the testis. They were also differentiated at the molecular level using the cox1 gene marker. Based on morphological and genetic evidences, three new species are described herein, namely Neopolystoma cayensis n. sp. and Neopolystoma guianensis n. sp. from the bladder and the conjunctival sacs of R. punctularia, respectively, and Neopolystoma scorpioides n. sp. from the conjunctival sacs of K. scorpioides. However the monophyly of Polystomoides and Neopolystoma is still questioned regarding their phylogeny based on a dataset comprising four concatenated genes, namely, 18S, 28S and 12S rRNA genes and cox1.ConclusionsIn addition to these being the first chelonian polystomes to be reported and described from French Guiana, they represent the first polystomes from the hosts K. scorpioides and R. punctularia and the first representatives of Neopolystoma from South America. Chelonian polystomes now require an in-depth morphological study to reconcile the taxonomy of the genera with species evolution.