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Simple Summary: Agricultural land is associated with destruction and fragmentation of natural habitats, but it can also serve as a habitat for many species. The aim of this study was to establish the abundance of three anuran species—the Marsh frog, the Eastern tree frog and the European green toad—across one natural (shallow pond) and two agricultural (rice fields) habitats near the city of Plovdiv, Central Bulgaria. Calling activity was recorded with acoustic loggers from June to September for two consecutive years. Our results indicate that all species had higher calling activity in the rice fields compared to the natural pond, and this should be considered during the process of pesticide use and approval in order to minimize the negative effect of toxic substances on anurans. Agriculture can have different effects on wildlife depending on land-use type and extensive/intensive practices. The aim of this study was to establish the significance of rice fields in Central Bulgaria as anuran habitats. We used Audiomoth acoustic loggers to record calling activity at three sites near the city of Plovdiv—one shallow pond and two rice fields—from June to September in 2022 and 2023. We registered the three most widespread species in the region—Bufotes viridis, Hyla orientalis and Pelophylax ridibundus—and created pattern-matching models for them using the free web interface Arbimon, which enabled us to perform presence/absence counts and abundance estimates. At the beginning and the end of the rice vegetation period, water samples were collected and analysed for 62 substances. Substance concentrations were compared between ponds and with LC50 data from the available literature. We registered 19 and 21 substances in 2022 and 2023, respectively, with concentrations within the accepted limits, and although some metals were near risk levels, this was not reflected in the presence counts or the abundance estimates. The results indicated that frog activity was not related to any of the registered substances, but that it was positively correlated with daily rainfall and was higher in the rice fields. [ABSTRACT FROM AUTHOR]

Freshwater vertebrate predators can exert trophic control over aquatic and littoral communities. Among these predators, post‐metamorphic anurans exhibit a biphasic trophic spectrum by foraging in both terrestrial and aquatic habitats. Many studies have described their diet through the classical taxonomic classification of prey. However, these singular diet habits imply a complex, time‐dependent, realised trophic niche in which predation pressure occurs over many consumers that fill diverse functional roles throughout the aquatic and terrestrial interface of ponds. Among anurans, marsh frogs (Pelophylax ridibundus) have been introduced outside their range in many countries and are now invading nationwide areas, particularly in western Europe. Focusing on their foraging specificities will therefore further the understanding of the trophic role of these alien taxa in pond environments that are highly colonised.We collected stomach contents from 761 marsh frogs from introduced populations in 19 ponds in southern France once a month over 4 months of their active period in the spring. The populations of marsh frogs were studied in a geographic area that was devoid of native water frogs and their origin tracks back as far as south‐eastern Europe (i.e., more than 1,000 km from the studied sites, as evidenced previously by genetic analyses).Marsh frogs exhibited generalist and opportunistic feeding strategies. The trophic niche was strongly asymmetrical and broader in the terrestrial environment than in the aquatic environment. However, predation occurred in communities of large freshwater macroinvertebrates and amphibians. Whereas the composition of the terrestrial diet exhibited strong seasonal variations, predation pressure was continuously exerted on the same aquatic organisms over time. Primary consumers and consumers at higher trophic levels frequenting aquatic benthic, vegetated, pelagic, and surface microhabitats were preyed upon, underlying the multidimensional extent of the predation spectrum.The diversified feeding strategies of alien marsh frogs highlight the extent of potential ecological control by predation on pond communities. Because of their wide trophic niche, they exert predation pressure on most pond organisms, triggering possible top‐down control of the overall aquatic communities.Our results show that the integration of the functional traits and microhabitats of consumed prey may aid in a better understanding of how predation by anurans may target specific components of pond communities. More particularly, this study raises concerns about the predatory role of introduced anurans in the context of biological invasions. [ABSTRACT FROM AUTHOR]

Evaluation of changes in the leukogram of adult marsh frogs Pelophylax ridibundus inhabiting the polluted sedimentation lake of the Brikel Thermal Power Station (TPS), southern Bulgaria, as biomarkers for ecological stress is presented. For a comparison, data for frogs inhabiting a less disrupted habitat (reference site, RS) are presented. Leukopenia in the blood of individuals of P. ridibundus inhabiting the sedimentation lake of the Brikel TPS was detected but not in frogs from the reference site. Furthermore, the differential leukocyte count of the affected frogs was characterised by neutrophilia, eosinophilia, monocytosis, basopenia and lymphopenia. The values of the neutrophil-lymphocyte (N/L) ratio of the frogs from the lake of the Brikel TPS were higher than that of the ones inhabiting the RS. These changes in the leukogram are indicators of the exhaustion of the immune system and of activation of the organism's defences in response to stress. The changes in the leukogram are interpreted as caused by the deteriorated water quality in the sedimentation lake as it contained toxicants (reactive water-soluble forms of nitrogen and phosphates) and industrial ash. The results from this study confirm the role of parameter changes in the leukogram of P. ridibundus as diagnostic biomarkers for ecological stress. [ABSTRACT FROM AUTHOR]

The study of the peculiarities of energy metabolism in populations of the marsh frog Pelophylax ridibundus from several reservoirs of the Kamchatka Peninsula with different temperature regimes revealed the temperature compensation of this parameter in tadpoles. The linear dependence of the tadpoles' metabolic rate on the average annual temperature of habitat was shown. It was found that stable inherited differences in the intensity of tadpoles' metabolism were formed in 30–20 years from the moment of the first introduction of the species into the reservoirs of Kamchatka. An assumption is made about the limit of adaptive diapason of the species for the development stage 39–40 of tadpoles of the marsh frog. [ABSTRACT FROM AUTHOR]

Simple Summary: National conservation management is informed by knowledge on the species diversity of the taxon group in focus, specifically on the occurrence of endemics. Turkey, at the intersection of the Caucasus, Irano-Anatolian, and Mediterranean biodiversity hotspots, harbors a rich anuran diversity including two species considered endemic. The species status of one of them, the Beyşehir water frog Pelophylax caralitanus, has been in question since its proposal in 2001. We provide evidence that mating vocalizations of this taxon do not differ sufficiently from those of the widespread P. bedriagae to function as a premating barrier between the two, preventing significant gene flux. The low degree of bioacoustic differentiation agrees with earlier genetic, karyological, and morphological findings. We conclude that the Beyşehir frogs do not deserve species status and that P. caralitanus are in fact P. bedriagae. Therefore, the number of endemic anuran species in Turkey decreases to one. Informed conservation management requires exact knowledge on the species diversity of the taxon group in focus within a geographic area, specifically on the occurrence of endemics. In Turkey, there are three water frog taxa of the genus Pelophylax; one is the widespread P. bedriagae, the other two are geographically restricted to either Thrace (P. ridibundus) or to the Anatolian Lake district (P. caralitanus). The species status of the Beyşehir frog P. caralitanus has been questioned since its proposal in 2001. We recorded and analyzed advertisement and release vocalizations at representative populations of Pelophylax taxa to assess the degree of inter-taxon differentiation and the potential for premating isolation. We found that P. bedriagae and P. caralitanus have much more similar vocalizations than both have compared to P. ridibundus. A functional bioacoustic premating barrier between bedriagae and caralitanus in syntopy does not exist according to our study. The low degree of bioacoustic differentiation mirrors earlier genetic, karyological, and morphological findings. We conclude that the Beyşehir frogs do not deserve species status and that P. caralitanus should be considered a junior synonym of P. bedriagae. Therefore, the number of endemic anuran species in Turkey decreases to one. [ABSTRACT FROM AUTHOR]

Studying the effects of neonicotinoids on non-target organisms is still an urgent task in today's world, where they are used in substantial quantities. Initially, it is interesting to find out the change in easy-to-detect parameters under insecticide exposure conditions that may indicate some exposure. Therefore, we investigated the parameters of oxidative changes (SOD, CAT, MDA, and total protein) in sexually mature marsh frogs caused by exposure to imidacloprid. Thirty frogs were selected for the experiment and divided into five groups of six individuals each. The exposure concentrations of imidacloprid were 10 µg/L and 100 µg/L. The duration of insecticide exposure was 7 and 21 days. After the finish of the experiment, the liver, kidney, and blood were taken from the animals under anesthesia. It was found that after 7 days of exposure, the group exposed to 100 µg/L imidacloprid solution had lower serum total protein than the control and 10 µg/L exposure groups (p<0.05). Also, after 21 days of imidacloprid exposure at a concentration of 100 µg/L, there was an increase in the SOD value in the frog liver compared to the control group (p<0.05). No significant differences were found in other parameters (p>0.05). The findings cast doubt on the unconditional use of common oxidative stress indices in adult marsh frogs as biomarkers of low-dose imidacloprid exposure. The obtained results for the adult marsh frog may support the possibility of using the liver SOD level only as a biomarker of imidacloprid exposure at environmentally significant concentrations. [ABSTRACT FROM AUTHOR]

Agriculture can have different effects on wildlife depending on land-use type and extensive/intensive practices. The aim of this study was to establish the significance of rice fields in Central Bulgaria as anuran habitats. We used Audiomoth acoustic loggers to record calling activity at three sites near the city of Plovdiv—one shallow pond and two rice fields—from June to September in 2022 and 2023. We registered the three most widespread species in the region—Bufotes viridis, Hyla orientalis and Pelophylax ridibundus—and created pattern-matching models for them using the free web interface Arbimon, which enabled us to perform presence/absence counts and abundance estimates. At the beginning and the end of the rice vegetation period, water samples were collected and analysed for 62 substances. Substance concentrations were compared between ponds and with LC50 data from the available literature. We registered 19 and 21 substances in 2022 and 2023, respectively, with concentrations within the accepted limits, and although some metals were near risk levels, this was not reflected in the presence counts or the abundance estimates. The results indicated that frog activity was not related to any of the registered substances, but that it was positively correlated with daily rainfall and was higher in the rice fields.

Determining the invasibility of habitats by alien species is crucial for understanding their spread potential, the habitats the most at risk and to implement adequate management actions. This is urgent for introduced taxa that show high invasion potential across broad geographical scales. We here assess these processes in invasive Pelophylax water frogs which are widespread colonizers across Western Europe and for which the invasibility of habitats remains to be quantified. Specifically, we used hierarchical occupancy models in a Bayesian framework to identify local- and landscape-scale features that can enhance occupancy of the most common invasive water frog, the marsh frog (P.ridibundus), in southern France. Water frogs were highly detectable and showed high occupancy across the invaded landscape. The invaders expressed a very broad habitat tolerance for both local- and landscape-scale variables while their invasion was facilitated by the occurrence of deep, permanent ponds with abundant aquatic vegetation and high sun exposure. Cross-validation showed a good transferability of models across space. The high invasibility of a wide range of habitats by Pelophylax water frogs is alarming and unveils their invasiveness, contributing therefore to explain their success of invasion over broad geographic scales. [ABSTRACT FROM AUTHOR]

Certain amphibian species have long served as a valuable protein source for humans, in addition to being good bioindicators for environmental pollutants. Hence, to investigate the consumption outcomes leading to potential health risks, we determined the trace element (TE) levels in the hind leg and liver tissues of marsh frogs (Pelophylax ridibundus), one of the delicacies of several cuisines today. The sediment, water, and frog tissue samples were collected from 15 different locations of NE Turkey and analyzed to determine the arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) concentrations. The TE concentrations in the sediment, water, and individuals were detected to show significant variations among sampling stations (p < 0.05). Yet, Cd and Pb concentrations of the hind legs cooked and enjoyed in the diets were determined below the European Commission's permitted levels. Furthermore, based on the TEs in edible tissues, consumption of the marsh frog did not appear to pose a risk to humans in terms of provisional tolerable weekly intake (PTWI), target hazard coefficient (THQ), and hazard index (HI). [ABSTRACT FROM AUTHOR]

Within the scope of this research, the chronic effects of ammonium nitrate, which is the most widely used fertilizer worldwide, on the tadpoles of Marsh Frog (Pelophylax ridibundus), the Iranian Long-Legged Frog (Rana macrocnemis), the Caucasian Parsley Frog (Pelodytes caucasicus) and the Variable Green Toad (Bufotes variabilis) were examined. To assess the chronic effects of the fertilizer, the tadpoles of all the species were exposed to 0, 5, 10, 15, 20, 25 mg/L concentrations in same conditions. The chronic concentrations were applied from the 25th developmental stage to the 42nd developmental stage. It was defined at the end of the experiments that although there were some variability between different populations of the same species or between different species in the observed effects, chronic levels of ammonium nitrate caused decreased growth rate, prolonging in time to complete metamorphosis, increased abnormalities, and mortality in general. Among the 4 amphibian species, the Variable Green Toad was the most damaged one in terms of growth reduction (on average 31-41 %), abnormality rates (on average 50-75 %), prolonged time to complete metamorphose (14-21 days on average) and mortality rates (%54-100). The most adaptive species and the least damaged one was an Iranian long-legged frog for growth reduction (on average 0-15 %), prolonged time to complete metamorphose (7-9 days on average), and mortality rates (%9-15). All the harmful effects of chronic fertilizer levels caused by agricultural activities in the region had very important for examined species in our researches and it can be said that important environmental and biodiversity problems may occur if certain precautions are not taken regarding the use of the fertilizers and if the attitudes of the farmers on this issue cannot be changed.

The tadpoles of four amphibian species, namely the Marsh Frog (Pelophylax ridibundus), the Iranian Long-Legged Frog (Rana macrocnemis), the Caucasian Parsley Frog (Pelodytes caucasicus) and the Variable Green Toad (Bufotes variabilis), were exposed to acute concentrations (0 to 500 mg/L) of ammonium nitrate to assess the lethal effects (larval growth, abnormalities, mortality, and LC50 values). Eggs of each species were obtained from clean and polluted habitats in the same region and the tadpoles for experiments were provided from those eggs in the laboratory conditions. Although there was some variability between different populations of the same species or between different species in the observed effects, acute levels of ammonium nitrate caused decreased growth rate and increased abnormalities and mortality in general. Among the 4 amphibian species, the Variable Green Toad was the most damaged one in terms of growth reduction (on average 77-83%), and abnormality rates, and the most damaged one in terms of mortality rates was the Marsh Frog (on average 61-72%). Additionally, the species with the lowest concentration of ammonium nitrate, which killed half of its population, was the Marsh Frog. LC50 values for two populations of Marsh Frog were 37 and 59 mg/L. As a result of our research, it was determined that the acute fertilizer levels caused by agricultural activities in the region had very important harmful effects for all the species we examined. In this context, it can be said that very important environmental and biodiversity problems may occur if certain precautions are not taken regarding the use of the fertilizers and if the awareness of the farmers using these fertilizers cannot be raised.

In this study, testicular and ovarian structures of economically important edible Pelophylax ridibundus (Pallas, 1771) were histologically examined before and after reproduction in male and female individuals. Fourty eight (24 ♀, 24 ♂) adult frogs were collected from Gölbaşı Lake in Hatay. The average weight and length values of female frogs collected from nature were found to be 56.61±19.59 g and 79.54±7.07 mm; while, the average weight and length values of male frogs were 36.63±12.84 g and 69.29±9.15 mm, respectively. Frogs were brought to the frog farm established in Aydıncık and placed in breeding ponds with a width of 1m2. Frogs in the ponds were brought to the laboratory of Iskenderun Technical University in different periods, before breeding (March) and after breeding (June). Then, histological samples were taken from ovary and testis. The female frogs were determined ready for reproduction. Moreover, a large number of mature oocytes in the before breeding ovaries in vitellogenic stage, while after reproduction oocytes in primary structure and oocytes which have atresia status observed. Also, increase in the thickness of the theca layer was determined. In the male frog seminiferous tubules containing a large number of spermatogonia, spermatocyte, spermatid and a small number of spermatozoons including sperm bundles and leydig cells were found before reproduction. After the reproduciton, the density of spermatogonia, spermatocyte and spermatids were decreased; while, the density of spermatozoon and sperm bundle were increased in the seminiferous tubules. This study will contribute to the determination of mating and spawning in frog breeding by revealing the histological status of the gonad structure of P. ridibundus in the breeding process.

Background. The growth of anthropogenic pressure on water bodies due to the expansion of agglomerations contributes to the reduction in the abundance of both rare and widespread amphibian species. We studied the features of Pelophylax ridibundus adaptations living in urban water bodies to anthropogenic pollution based on the study of a number of morphometric and biochemical parameters. Materials and methods. For the study, three reservoirs were used on the territory of the city of Makhachkala with varying degrees of pollution, based on the calculation of the coefficient of complexity of environmental pollution. In mature P. ridibundus, after spawning, morphometric measurements were taken, body weight was measured, linear indices were calculated, and the content of total protein, cholesterol in tissues, and blood glucose was determined. Results. In the course of studying the morphometric parameters of P. ridibundus in a polluted environment, a decrease in the morphometric parameters of the body, the presence of size-weight sexual dimorphism, and an increase in the size of the head and limbs in females were noted. Correlation analysis showed the presence of a negative correlation in females between the L/L.c. and F/T indices from polluted water bodies and a positive correlation from a water body with a low degree of pollution. In males, only a positive correlation was noted. According to the factor analysis of variance, it was revealed that environmental pollution affects the decrease in body weight, cholesterol and glucose levels, as well as an increase in the total protein content in P. ridibundus tissues (R2 ≥ 53 %, p ≤ 0.05). Some parameters are also affected by gender, as well as the interaction of two factors. Conclusions. The population variability of body weight and biochemical parameters in P. ridibundus is largely due to environmental pollution, while the variability of morphometric parameters both within and between populations is due to a complex of factors, where the degree of environmental pollution affects to a lesser extent.

Associational effects such as "associational resistance" or "aposematic commensalism" may facilitate the subsequent evolution of mimicry. However, such effects are usually expected to be contingent on a spatiotemporal co-occurrence of defended and undefended species. Associational resistance may emerge in communities of larval anurans where tadpoles of different species share a generalized morphology but vary in chemical defences. In Europe, the marsh frog Pelophylax ridibundus reproduces in fish-containing habitats that earlier in the season can be used by the common toad Bufo bufo, a species with chemically defended larvae. In a mesocosm experiment, we investigated if the associational protection against predation provided by the defended species could be strong enough to last even after the defended prey metamorphose and leave the system. We expected that the higher abundances (both absolute and relative) of chemically defended B. bufo in the tadpole assemblage exposed to predation by the common carp Cyprinus carpio prior to the occurrence of P. ridibundus tadpoles would be related to the increased later survival of P. ridibundus in the presence of the same fish. The tadpoles of P. ridibundus were highly vulnerable to predation during a 2-week cohabitation with fish. We found no relationship between the survival of P. ridibundus and the absolute density or relative proportion of B. bufo. Although associational effects may be ecologically relevant in aquatic animal communities, they apparently require the co-presence of the defended prey in fish-tadpole interactions. [ABSTRACT FROM AUTHOR]

Informed conservation management requires exact knowledge on the species diversity of the taxon group in focus within a geographic area, specifically on the occurrence of endemics. In Turkey, there are three water frog taxa of the genus Pelophylax; one is the widespread P. bedriagae, the other two are geographically restricted to either Thrace (P. ridibundus) or to the Anatolian Lake district (P. caralitanus). The species status of the Beyşehir frog P. caralitanus has been questioned since its proposal in 2001. We recorded and analyzed advertisement and release vocalizations at representative populations of Pelophylax taxa to assess the degree of inter-taxon differentiation and the potential for premating isolation. We found that P. bedriagae and P. caralitanus have much more similar vocalizations than both have compared to P. ridibundus. A functional bioacoustic premating barrier between bedriagae and caralitanus in syntopy does not exist according to our study. The low degree of bioacoustic differentiation mirrors earlier genetic, karyological, and morphological findings. We conclude that the Beyşehir frogs do not deserve species status and that P. caralitanus should be considered a junior synonym of P. bedriagae. Therefore, the number of endemic anuran species in Turkey decreases to one.

Frogs can be added to a list of different raw materials which have sustainable economic value to their producers. Therefore, the biochemical attributes of the frogs require further scientific scrutiny. The major objective of the current study is to investigate some biochemical compositions of edible portions of Pelophylax ridibundus (Pallas, 1771) grown in different conditions. The wild frogs, semicultured frogs, and cultured frogs were investigated regarding female and male specimens, leading to six groups that were determined to investigate the biochemical features of frogs. The results show that they (all frogs in all six groups) have low lipid contents (p < 0.05). The protein contents of the frogs varied in the range of 10.54%-16.10%. The lowest ash contents were found in semicultured male and female frogs. The average moisture contents were roughly 80% for all specimens. The major fatty acids were C16:0, C18:0, C18:1n9, C18:2n6, and C20:4n6 for wild, semicultured, and cultured frogs, respectively, for both sexes, showing their respective amounts varied among groups. All in all, the results show that there exist some differences in the nutritional content of frogs grown in different conditions in terms of the analyzed parameters. [ABSTRACT FROM AUTHOR]

The present study was carried out on 10 frogs, Pelophylax ridibundus (Pallas, 1771), captured near the river Bahlui, Iasi, between April and May, 2019, for the study of digestive helminths and their effect on the digestive tract. Macroscopic examination of the general cavity revealed distension of the small intestine. The sectioning of the intestinal wall revealed a variable number of parasites (1 – 12) with a whitish cylindrical body, anchored in the duodenal mucosa. The morphological study of the parasites confirmed the species as Acantocephalus ranae. The prevalence of the infection was 60 % and the average intensity was 4.83 ± 4.15. Lesions of the small intestine were characterized by catarrhal enteritis, hemorrhagic spots and ulcers on the mucosa, occlusion and obstruction of the intestinal lumen. Histologically, eosinophilic inflammatory infiltrate in the glandular crypts, mucosal and submucosal edema, fibrosis and conjunctival hyperplasia, total mucosal atrophy, were found. The infection with Acanthocephalus ranae in Pelophylax ridibundus caused severe pathological changes, conditioned by the intensity of the infection, aspects revealed for the first time in Romania.

The genotoxicity and erythrocyte nuclear abnormalities in adult marsh frogs Pelophylax ridibundus inhabiting polluted industrial area at the city of Plovdiv, south Bulgaria, were evaluated as biomarkers for ecological stress. The present work is a part of a large-scale in situ study aimed at an assessment of the negative effects on P. ridibundus of the chronic impact of high doses of toxicants (mainly nitrates, nitrites, ammonium and heavy metals) entering its habitat with industrial waste waters. For a comparison, frogs from a less disrupted habitat (reference site) were used. Frequencies of micronuclei (MN), erythrocyte nuclear abnormalities (ENAs), mitosis and immature erythrocytes of frogs from the two sites were compared. Significantly higher MN and ENAs frequencies in frogs from the polluted site were registered. Industrial waste waters and the toxicants (reactive forms of nitrogen and heavy metals) in them are suggested as the reason for the genotoxic damages in erythrocytes of frogs from the polluted site. [ABSTRACT FROM AUTHOR]

Samples of marsh frogs (Pelophylax ridibundus) were collected from two thermal reservoirs in the southeastern part of the Kamchatka Peninsula: (1) from a discharge channel of Thermal Power Plant no. 2, Petropavlovsk-Kamchatsky (hereinafter TPP); and (2) from thermal waste waters of the Township of Paratunka (hereinafter Paratunka). The concentrations of iron and manganese in the TPP waters are higher than in Paratunka by 7 and 1.2 times, respectively; while the concentrations of cobalt, copper, and nickel in the TPP waters are lower in comparison with Paratunka. The striata and hemimaculata phenetic morphs predominate in the Paratunka population; while maculated (maculata), white-throated (albicollis), and white-bellied (albiventris) individuals predominate in the TPP population. Both males and females in the TPP population feature higher average age, body length, body weight, and postmetamorphic growth rate values in comparison with the Paratunka population. Males in the TPP population feature a significantly higher relative testes mass, which can be a compensatory reaction to the complex of pollutants. For the first time, the predominance of erythrocytes with attached micronuclei was identified in marsh frog populations of Kamchatka, which indicates chromosomal aberrations induced by mutagens present in the aquatic environment. Sexual differences in the proportion of erythrocytes with attached micronuclei have been identified in frogs of the Paratunka population, which indicates a higher mutation frequency in erythrocytes of males in comparison with females. The proportion of micronuclei increases in erythrocytes of older individuals; apparently, this is due to the cumulative effect of xenobiotics present in the aquatic environment. The morphophysiological indices (i.e., relative masses) of organs make the highest relative contribution to the total variance of the set of characteristics studied in marsh frogs belonging to two different populations; while cytogenetic disordersin somatic cells identified by the micronucleus test make the greatest difference in sexual differences (Paratunka population only). [ABSTRACT FROM AUTHOR]

A wild-caught mature female marsh frog (Pelophylax ridibundus) was presented for a left-sided dorsal swelling. No other abnormalities were detected during the examination. Fine-needle aspiration was non-diagnostic. Baseline hematological and biochemical analyses were within normal reference ranges, and medical imaging did not provide further useful information. Surgical exploration under general anesthesia was performed. The swelling was confirmed to be a digestive tract hernia protruding through a breach of the dorsal muscles and coelomic membrane. Reduction of the hernia was made difficult by the presence of multiple adhesions between the herniated tissue and the coelomic membrane, suggesting a relatively chronic lesion. A traumatic cause was hypothesized. One month later, the animal was considered healed and released back into the wild. Hernias in amphibians are poorly reported in the literature and historically are only found ventrally. To the best of our knowledge, this is the first report of a dorsal hernia in a captive or a wild amphibian. [ABSTRACT FROM AUTHOR]

The health status of Pelophylax ridibundus species living in anthropogenic pollution sources in Erzurum (Turkey) were investigated. Firstly, heavy metal concentrations in liver of the frog species, and in water and sediment samples taken from the habitats of the frogs were determined by instrumental analysis. Secondly, morphometric (fluctuating asymmetry-FA, hepatosomatic index-HSI) and erythrometric analyses were performed to reveal the health status of the frogs in the areas. Our study provides the first morphometric datas on the frog in Turkey. Although the metal concentrations in the water were high, it was determined that they did not exceed the limit values. However, Cr, Ni, Zn, and As metal concentrations in the sediment were determined to be above the acceptable level. It was also found that some metals accumulated in the livers of the frog due to heavy metal pollution. On the other hand, the FA, HSI values and the erythrocytic nuclear abnormality frequency increased in the frogs living in polluted stations. Moreover, erythrocyte size decreased and nucleated erythrocyte, mitotic erythrocyte, pycnotic erythrocyte, and immature erythrocyte frequencies increased. It was found that there was a correlation between the presence of pollution and the health status of the frogs, and the frog populations were affected negatively by anthropogenic pollution. [ABSTRACT FROM AUTHOR]

Doğadan toplanan erkek ve dişi kurbağaların (Pelophylax ridibundus), boy uzunluğu (SVL) ve arka bacak uzunluğu ile karkas, arka bacak, deri, baş ve karaciğer ağırlığı alınarak karkas miktarı belirlenmeye çalışılmıştır. Dişi kurbağaların ortalama SVL değeri 91,6±0,53 mm, erkeklerin 81,1±0,69 mm olarak ölçülerek, aradaki farkın istatiksel açıdan önemli olduğu tespit edilmiştir. Gıda olarak tüketilen arka bacakların ortalama uzunluk değerleri, dişi kurbağalarda 72,0±0,65 mm, erkek kurbağalarda 68,0±0,53 mm tespit edilmiş ve aradaki farkın istatiksel açıdan önemli olduğu görülmemiştir. Arka bacakların ortalama ağırlıkları dişi kurbağalarda 21,45±5,06 g, erkek kurbağalarda 15,53±2.94 g olduğu ve her iki cinsiyette de bu miktarların toplam vücut ağırlığının yaklaşık %25’ine denk geldiği belirlenmiştir. Çalışma esnasında dişi kurbağaların sırasıyla vücut, karkas ve gıda olarak tüketilen arka bacaklarının ortalama ağırlıkları, erkek kurbağalara göre daha yüksek miktarda tespit edilmiş olup; dişi kurbağalar ile erkek kurbağalar arasındaki bu ağırlık farkları aynı zamanda istatistiksel açıdan önemli bulunmuştur. Karkas ağırlıkları, hem dişi hem de erkek bireylerde toplam ağırlığın yaklaşık olarak %50’sini oluşturmaktadır. Kesim işlemi sonucunda karkas dışında kalan; deri, baş ve karaciğerin ortalama ağırlıkları dişi kurbağalarda erkek kurbağalara oranla daha fazla miktarda bulunmuştur. Dişi ve erkek bireyler arasında baş ağırlığı hariç karkas dışında kalan diğer kısımlar arasındaki farkların önemli olduğu belirlenmiştir. Kurbağa derisi önemli bir sanayi ürünü olup, miktarı dişi kurbağalarda ortalama 8,07±2,04 g, erkek kurbağalarda ortalama 5,66±1,21 g bulunmuştur. Bu değerlerin oranı, toplam vücut ağırlığının %10’una denk geldiği tespit edilmiştir. Bu çalışmada, dişi kurbağaların erkek kurbağalardan karkas kazancı bakımından daha iyi olduğu ve karkas miktarı dışında kalan, baş, karaciğer ve derinin miktarı tespit edilerek değerlendirilmesi araştırılmıştır.

The distribution of species of Hepatozoon from anurans, specifically frogs, and their hostparasite relationships are of great interest. Due to the specifics of the ontogeny of frogs, they form a link between aquatic and terrestrial ecosystems. These amphibians are important in food chains, ensuring the normal functioning of biocenosis. In this study, we present data on the presence of Hepatozoon sp. in the marsh frog, Pelophylax ridibundus (Pallas, 1771) for the first time in Bulgaria. The blood smears of 137 individuals were investigated by fluorescence microscopy after staining with acridine orange. In three of five studied localities, the presence of apicomplexan haemoparasite from the genus Hepatozoon was revealed. Prevalence and parasitaemia values were different in frogs populations inhabiting the Chaya River (27.5% and 11.0%, respectively), Tsalapitsa Rice Fields (6.4% and 9.9%, respectively) and nature wetland Zlato pole (10.0% and 8.1%). It was found that the morphology and morphometric parameters of the parasite gamonts are closest to Hepatozoon magna, but molecular tools are required to confirm the genus and species determination. Our findings revealed that acridine orange is appropriate dye for detecting haemoparasites of the genus Hepatozoon. [ABSTRACT FROM AUTHOR]

Amphibians have big potential as bioindicators based on their combined life cycle as aquatic and terrestrial form. They can play the role of prey or predator, making them a key element in toxic substances transfer between aquatic and terrestrial habitats. The nuclear abnormalities (NAs) in amphibians' erythrocytes in recent years have been used as a successful biomarker for anthropogenic pollution. The NAs including micronuclei in erythrocytes of the marsh frog (P. ridibundus) have been studied to assess the cytotoxic and genotoxic effect in heavy metal polluted area in situ. Here we assess the cyto- and genotoxic potential of the polluted waters (Chaya River) close to the lead-zinc smelter near Plovdiv (Bulgaria) situated in an area that has been contaminated with heavy metals for 60 years. Frogs from Strandzha Natural Park were used as a negative control. Peripheral blood smears have been dyed with acridine orange. NAs of the following types: notched nuclei, nuclear buds and blebbed nuclei have shown the highest frequency. There is no sexual dependence in the formation of different types of NAs. The significant differences (P=0.0001) in the mean Total NAs (?) in erythrocytes of marsh frogs from the polluted area compared to the total NAs from the background region "Strandzha" NP demonstrate the presence of in vivo active cytotoxic and genotoxic agents in the impacted area. The obtained results for NAs in erythrocytes of P. ridibundus are evidence for successful application of NAs as a biomarker in amphibians for the purpose of biomonitoring. [ABSTRACT FROM AUTHOR]

The life cycle of the nematode Cosmocerca ornata (Dujardin, 1845)—a parasite of amphibians—was studied for the first time. The experimental infection of yearlings of the marsh frog Pelophylax ridibundus infected by larvae of C. ornata was performed. The development stages of parasites in the host were studied. It has been revealed that amphibians are infected with infectious larvae (J3) of nematodes in the surface-water layer by the penetration of parasites through eyes onto the conjunctiva under the lower eyelid, where the larvae undergo the third and fourth molting. Then the parasites migrate into the oropharyngeal cavity and through the digestive tract to the place of constant localization: the posterior part of the intestine. Morphological descriptions and original drawings of J3 and J4 juveniles, molting juveniles, and adults of C. ornata are given. The development stages of the juveniles are diagnosed by the body size, location of the genital primordium, and forming copulative structure. The sex of the nematodes can be identified at the third molt stage. Mature nematodes differ from juveniles by the presence of copulative organs: the vulva in adult females and spicules in adult males. The time of the development stages of C. ornata and the total life span of the parasite in the host is determined. The effect of ambient temperature on the period of development of nematodes in amphibians is established. [ABSTRACT FROM AUTHOR]

Background: Amphibians decline globally due to infection with virulent bacteria, despite their vital roles in the ecosystem. The current study aimed at addressing the pathological and bacterial findings of the infected Pelophylax ridibundus indigenous to the Al‐Ahsa region. Many clinical signs were observed in the eggs, including discoloration, disintegration of the outer jelly coat; defects in morphology, and mortality were reported. Furthermore, neuromasts lacking apical cilia and microvilli were observed in the cleavage stages of the infected developing egg. Additionally, cutaneous hyperaemia, lethargy, peripheral oedema, subcutaneous haemorrhage and cutaneous ulcerations were observed in the infected P. ridibundus adults. Methods: Ribbons of frog eggs were collected from Al‐Ahsa oasis, the Eastern region, Kingdom of Saudi Arabia (KSA), and examined under light and scanning electron microscope. The developed eggs and adults were further examined using a dissecting microscope to determine signs of infection. A bacterial strain designated as PRE‐1 was isolated from the infected eggs, identified genotypically and then characterized phenotypically. Strain PRE‐1 was identified as Aeromonas hydrophila based on the comparative gene sequences of the 16S rRNA gene at identity level of (99.92%). Furthermore, phylogenetic relationship based on the 16S rRNA gene sequences of our strain and other relevant strains Aeromonas spp. showed that PRE‐1 formed a cluster with A. hydrophila (99% bootstrap support), providing a robustness to the identification of PRE‐1 as A. hydrophila. This bacterium was found to be associated with disease outbursts in the marsh frogs from the Al‐Ahsa region. Conclusion: It is important to continue monitoring the emerging diseases so that their cause can be discerned, and appropriate protocols can be applied to limit the spread of the loss of amphibians, which are vital for our ecosystem. [ABSTRACT FROM AUTHOR]

Illumination and light spectrum have the most diverse effects on animals. However, their role in the development of amphibian larvae has been little studied. This study is aimed to study the effects of illumination and light spectrum on the growth and development of Pelophylax ridibundus larvae. The study has been conducted in experimental conditions. Roe has been obtained from a natural reservoir from one clutch. The larvae have been placed in aquariums and had been grown before the appearance of juveniles under illumination from 0 to 2400 lx in different spectrum colours (from red to blue). It has turned out that a wide range of illumination (from 3 to 2400 lx) has a positive effect. On the contrary, the larvae mortality and the duration of the larval development and metamorphosis climax increased in conditions of round-the-clock darkness. The tadpoles growth increases while the duration of the larval development reduces compared to the control (normal lighting) under blue light. The length and mass of the larvae decrease under red illumination compared with the control. Mechanisms of the possible light influence on Pelophylax ridibundus are discussed. [ABSTRACT FROM AUTHOR]

In order to determine the effects of environmental contamination, nuclear abnormalities of peripheral erythrocytes and lung, liver, and kidney histopathologies were evaluated in marsh frog (Pelophylax ridibundus) in agricultural areas. The most prominent histopathological alterations observed in lung tissue were noted as epithelial hyperplasia, thickness of alveolar septa, dilatations and congestions of blood capillaries, and melanomacrophage accumulation. An increase in the number and widening of melanomacrophage centers were also noted for liver, in parallel with hepatocyte degeneration and heterogenic vascular construction originating from congestion, deformation and dilatation. In kidney, degeneration, congestion, dilatation, and necrosis in proximal and distal tubules were recorded; moreover, expansions of Bowman's space, infiltrations of lymphocytes, and glomerulonephritis were observed. Also, the frequency of nuclear abnormalities in erythrocytes showed significant differences between the sites. Quantitative analyzes of histopathological and nuclear alterations indicated that the highest effects of pollutants in frogs were at the agricultural sites in June. [ABSTRACT FROM AUTHOR]

It is known that amphibians inhabiting agricultural areas are constantly exposed to chemicals such as insecticides. Deltamethrin, a type II pyrethroid insecticide, is widely used in the world. The present study aimed to investigate the toxic effects of different concentrations (0.625, 1.25, and 2.50 mg/kg body wt) of orally applied deltamethrin to marsh frog (Pelophylax ridibundus) after 96 h of treatment. The histopathological abnormalities in liver, gastrointestinal tract, and kidney tissues were evaluated with quantitative analyses. In liver, increase of melanomacrophagic aggregates, non-homogeneous hepatocyte parenchyma, sinusoidal dilatations, infiltration, vascular epithelial degeneration, central vein degeneration, and congestion were determined in exposed frogs. In gastrointestinal tract, vacuolization, hypertrophy, congestion, infiltration, necrosis, and erosion of the epithelial layer, increasing goblet secretion, degeneration in villi, epithelial disorganization, and edema were observed in high-dose groups. In all experimental groups, glomerular shrinkage, hemorrhage, degeneration, infiltration, increase in Bowman distance, and eosinophilic-stained tubular lumens were detected in kidneys. Histopathological changes were more prominent in 1.25 and 2.50 mg/kg groups than the other groups. To determine the genotoxic effects of deltamethrin, the peripheral blood samples of the frogs were used. The erythrocytic nuclear abnormalities such as micro-nucleus, double-nucleus, kidney-shaped nucleus, notched nucleus, and bud nucleus were determined in the frogs, and the genotoxicity did not show a significant increase between control and low-dose groups, statistically. However, the genotoxic effects increased in medium- and especially high-dose groups. The results of this study showed that acute deltamethrin exposure can lead to histopathologic and genotoxic effects in P. ridibundus. [ABSTRACT FROM AUTHOR]

A comparative analysis of the trematode fauna of the marsh frog Pelophylax ridibundus from different habitats of the National Park «Samarskaya Luka» is given. It is based on the authors' own materials collected in 1998‒2001 on three locations: on the coast of the Volga channel, floodplain lakes and nearby islands. Twenty-two trematode species were found. Differences in the composition of trematodes and the nature of infestation of amphibians from different biotopes have been revealed. It has been established that the diversity of trematodes and their infectivity are higher in amphibians in floodplain lakes with relatively constant environmental conditions. Frogs from river coast habitats with dynamic environmental conditions are less infected with the same diversity of species. Amphibians of isolated island habitats are characterised by relatively small number of trematode species and a low level of helminth invasion. The causes of differences in amphibian infestation by trematodes in different biotopes are complex. Diversity, high abundance of mollusks and arthropods (intermediate hosts) cause a high level of infestation of frogs with sexually mature flukes, transmitted through food chains. The high density of the amphibians themselves, and, accordingly, of the predators batrachophages, leads to intensive infestation of frogs by larval stages of trematodes. A literature review of the data on the influence of abiotic and biotic factors of the environment on amphibian trematode is given. The formation of the trematode fauna of frogs is influenced by a number of environmental factors acting in the aggregate: the hydrological regime of the reservoir, the diversity and density of populations of intermediate, reservoir and definitive hosts of trematodes in the biocoenosis.

A high level of biological diversity, including amphibians, is characteristic for Protected Areas. The group of the European green frogs has a special interest because they are characterised by unique genetic and ecological interactions in the process of hybridogenic reproduction. In 2000–2018 in the Middle Volga Region we studied green frogs in five nature reserves (Mordovia State Nature Reserve, State Nature Reserve «Prisurskiy», Volzhsko-Kamskiy State Nature Biosphere Reserve, Zhiguli State Nature Biosphere Reserve, and State Nature Reserve «Privolzhskaya lesostep'») and four national parks (National Park «Smolny», National Park «Chavash Varmane», National Park «Samarskaya Luka», and National Park «Buzulukskiy Bor»). These Protected Areas are located in a zone of overlap of ranges of Pelophylax lessonae and P. ridibundus, i.e. in area of potential spread of their meroclonal hybrid P. esculentus. Pelophylax ridibundus inhabits eight studied Protected Areas, while P. lessonae has been registered in seven and P. esculentus only in five of them. Two molecular-genetic markers were used in the study: mitochondrial COI and nuclear SAI-1. Mitotypes and alleles of two cryptic forms of P. ridibundus were revealed here, a «western» (P. ridibundus) and «eastern» (P. cf. bedriagae). In the Protected Areas we found four (of six which are possible) combinations of mitotypes of mitochondrial DNA and alleles of nuclear DNA of these two forms, and only one combination in P. esculentus. Six types of population systems of green frogs are presented in the studied Protected Areas. Single-species systems, including P. ridibundus (n = 16; 41.0%) or P. lessonae (n = 10; 25.6%), predominated. Among mixed systems a type including all three species was most common (n = 6; 15.4%). Two-species systems were the rarest: P. ridibundus and P. lessonae (n = 3; 7.7%), P. esculentus and P. lessonae (n = 3; 7.7%), P. ridibundus and P. esculentus (n = 1; 2.6%).

The introduction of alien water frogs is perhaps one of the most underestimated herpetological conservation issues in Europe. The identification of distinct species is highly challenging at the phenotypic level, and artificial syntopy between various taxa and lineages may lead to diverse outcomes, including hybridisation and local extinction. In central Italy the native synklepton of Pelophylax bergeri (the parental taxon) and P. kl. (klepton) hispanicus (the hybridogenetic hybrid, which clonally transmits the genome of an extinct ridibundus-like taxon) is present. Until recently, data regarding the presence of alien water frogs in central Italy was scarce, and no alien taxa have been reported for Tuscany. In this study, four distinct non-native Pelophylax lineages have been identified via molecular analysis in the Cecina and Arno river basins and ascribed to the Marsh frog group (P. ridibundus sensu lato). Alien Pelophylax ridibundus, P. kurtmuelleri, and P. cf. bedriagae sensu stricto currently appear to be widespread in the Cecina basin. Furthermore, evidence of hybridisation with autochthonous taxa has been suggested by genetic analyses in four out of eight sampling localities. With a view to evaluate urgent conservation strategies, a greater sampling effort is required to assess the actual distribution and ecology of the alien lineages, and further research is necessary to measure their impact on the native hybridogenetic system of the central-southern Italian pool frogs. [ABSTRACT FROM AUTHOR]

Methods for morphological identification of water frogs from the Pelophylax esculentus complex have changed over the decades. Still, without resort to genetic analyses, water frogs remain among the most difficult European amphibians to distinguish due to their hybrid nature. The aim of this study was to identify a reliable set of quantitative and qualitative morphological characters that objectively resolve species' identification in the Pelophylax esculentus complex and provide a rapid and robust procedure for taxon identification. Our results showed a substantial difference in morphological characteristics among taxa. The shape and size of the metatarsal tubercle along with the coloration of the hind limbs and flanks appear to be the most important diagnostic traits. Linear discriminant analysis with both quantitative and qualitative traits as a rapid method for the assessment of water frog taxa showed satisfactory accuracy and prediction classification for all 3 members of the complex. [ABSTRACT FROM AUTHOR]

The frog has a highly developed nervous system. It consists of a brain, a spinal cord and nerves. The brain is the only center for the control of all vital activities as it receives impulses from different parts of the body through sensory nerves and issues orders through motor fibers to different parts of the body for appropriate action. The Aims of studyis general morphological structural of the brain and spinal cord in the Iraqi frog Rana ridibunda ridibunda. The brains of twenty of frogs belonging to class Amphibia were studied using conventional techniques of dissecting microscopy. All samples were sacrificed and anesthetized and then they were removed completely from the neurocranium, cranial, sensory nerves and the meninges and transported and then fixation in formalin solution (10%) before further dissection and analysis. The results showed the basic structure of the central nervous system in the Iraqi frog Rana ridibunda ridibunda consists of the brain and the spinal cord. The brainis divided into three parts: Proncephalon, Mesencephalon and Rhombencephalon. The Telencephalon (olfactory lobes, cerebral hemispheres) and diencephalon are included in the Proncephalon (forebrain). A pair of optic lobes is present in the Mesencephalon (midbrain). Cerebellum (Metancephalon) and medulla oblongata (Myelencephalon) are part of the Rhombencephalon (hindbrain). The spinal cord is the posterior continuation of brain which housed within the central canal of a vertebral column,it stats from the foramen magnum and end in the thin filament (filum terminate). The spinal cord was subdivided into four regions including cervical, thoracic, lumbar and sacral and additional to dorsal and ventral longitudinal groove were observed on each surface side of the spinal cord. The generality of the findings indicate that an amphibian including frogs continue to form a highly amenable vertebrate model system to illustrate general principles of organization of nerve system [ABSTRACT FROM AUTHOR]

In the last 10 years, many atypical novel members of Brucella species have been reported, including several Brucella inopinata‐like strains in wild‐caught and "exotic" amphibians from various continents. In 2017, a strain of Brucella was isolated for the first time in animals from a French farm producing frogs—Pelophylax ridibundus—for human consumption and identified as B. microti‐like. Following this first isolation, investigations were performed in this farm as well as in the farm of the research unit that provided the domestic frog strain to estimate the prevalence of B. microti‐like infection and its presence in the surrounding environment. Farming practices were investigated and samples including frogs at different development stages, surface tank swabs, water, feed and soil were analysed by real‐time PCR and bacteriological methods. High B. microti‐like prevalence values (higher than 90%) were obtained in frog samples in the commercial farm, and its presence was highlighted in the environmental samples except feed. In the research unit farm, B. microti‐like species was also isolated and detected in frog and environmental samples. These results show that B. microti‐like organisms are able to colonize amphibians and persist in their environment. Its presence could constitute a possible risk for consumers and workers proving the importance of assessing the zoonotic and pathogenic potentials of these new and atypical Brucella species. [ABSTRACT FROM AUTHOR]

The paper examines the effects of the antimicrobial agent triclosan on the functioning of the liver mitochondria of marsh frog (Pelophylax ridibundus (Pallas, 1771)). It was established that triclosan inhibits DNP-stimulated respiration of mitochondria and decreases respiratory control ratio. In addition, triclosan causes the collapse of the mitochondrial membrane potential on both types of substrates. Such an action of triclosan can be mediated by both a protonophore effect and suppression of the activity of complex II and combined activity of complexes II + III (and, to a lesser degree, the combined activity of complexes I + III) of the mitochondrial respiratory chain. It is shown that high concentrations of triclosan enhance the production of hydrogen peroxide during the oxidation of substrates of the complex I by mitochondria, and decrease it in the case of succinate oxidation. It is found that triclosan is able to induce nonspecific permeability of the liver mitochondria of these amphibians, as well as the plasma membrane of erythrocytes. The possible mechanisms of triclosan effect on marsh frog liver mitochondria and red blood cells are discussed. [ABSTRACT FROM AUTHOR]

The paper presents data on the identification of the helminth fauna structure of Pelophylax ridibundus species and the determination of its role as intermediate and paratenic host for various groups of vertebrate helminths. 84 specimens of Pelophylax ridibundus (26 - males, 31 - females, 27 - juveniles) from the Dniester River, border area of Talmaza village, Ștefan Vodă district, were helminthologically investigated. As result of helminthological investigations, it was established that the structure of the helminth fauna of Pelophylax ridibundus species is characterized by 13 species of helminths (Haematoloechus variegatus Rudolphi, 1819; Codonocephalus urniger Rudolphi, 1819; Opisthioglyphe ranae Froelich, 1791; Paralepoderma brumpti Buttner, 1951; Prosotocus confusus Looss, 1894; Tylodelphys excavata Rudolphi, 1803; Diplodiscus subclavatus Pallas, 1760; Parastrigea robusta Szidat, 1928, Strigea falconis Szidat, 1928; Cosmocerca ornata Dujardin, 1845; Oswaldocruzia filiformis Goeze, 1782; Icosiella neglecta Diesing, 1851; Spirocerca lupi Rudolphi, 1809), from 13 genera, 11 families (Omphalometridae, Haematoloechidae, Plagiorchiidae, Lecithodendriidae, Diplodiscidae, Diplostomatidae, Strigeidae, Cosmocercidae, Molineidae, Onchocercidae, Spirocercidae), 6 orders (Plagiorchiida, Echinostomida, Diplostomida, Ascaridida, Strongylida, Spirurida), 2 classes (Trematoda, Secernentea) and 2 phylums (Plathelminthes, Nematoda). Of the 13 helminth species detected, a special importance is attributed to the nematode Spirocerca lupi Rudolphi, 1809, for which the taxonomic classification, synonims, hosts, organic specificity and biological cycle are described, for which the Pelophylax ridibundus species is as paratenic host. The diversity and intensity of helminth infestation of Pelophylax ridibundus has been established. [ABSTRACT FROM AUTHOR]

Anurans have been introduced in many parts of the world and have often become invasive over large geographic areas. Although predation is involved in the declines of invaded amphibian populations, there is a lack of quantitative assessments evaluating the potential risk posed to native species. This is particularly true for Pelophylax water frogs, which have invaded large parts of western Europe, but no studies to date have examined their predation on other amphibians in their invaded range. Predation of native amphibians by marsh frogs (Pelophylax ridibundus) was assessed by stomach flushing once a month over four months in 21 ponds in southern France. Nine percent of stomachs contained amphibians. Seasonality was a major determinant of amphibian consumption. This effect was mediated by body size, with the largest invaders ingesting bigger natives, such as tree frogs. These results show that invasive marsh frogs represent a threat through their ability to forage on natives, particularly at the adult stage. The results also indicate that large numbers of native amphibians are predated. More broadly, the fact that predation was site- and time-specific highlights the need for repeated samplings across habitats and key periods for a clear understanding of the impact of invaders.

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In this study, the effects of a neonicotinoid insecticide acetamiprid on the sciatic nerve of Rana ridibunda were investigated by using electrophysiological and histological methods. A total of 35 preparations of sciatic nerve isolated from 35 frogs (Nervus ischiadicus) were used in the experiments. Experiments were designed as four different dose groups (n = 8 per group). Acetamiprid solutions of 1 (group 1), 10 (group 2), 100 (group 3), and 1000 μ;M (group 4) were applied to the nerves in dose groups. In each group, action potentials were recorded before application of acetamiprid which served as control data. The extracellular action potentials were recorded for each group of 30th, 60th, 90th and 120th min of application time. Action potential amplitude and area were measured from recordings. Histological evaluation was performed by transmission electron microscopy. In electrophysiological examination, all doses in which acetamiprid applied have shown the effect from the 30th min and suppressed the sciatic nerve action potential. Acetamiprid significantly reduced the amplitude at the rate of 78-96% and the area at the rate of 79-98% (p < 0.05). In electron microscopic examination, the control nerves were in normal appearance. Disorganization, irregularity, dense ovoid body formation, fragmentation of the myelin sheath, and loss on some axoplasm of the nerves in the dose group have been observed. Our findings showed that acetamiprid can cause neuropathic changes in sciatic nerve at all applied doses. These results indicate that acetamiprid as other insecticides can have harmful effects on non-target organisms [ABSTRACT FROM AUTHOR]

Sardinian herpetofauna represent a valuable biodiversity resource in the Mediterranean Basin. Among amphibians, most of the taxa are indeed endemic to the island. In contrast, water frogs of the Pelophylax genus are considered allochthonous to Sardinia, and are traditionally assigned to the Italian pool frog (P. bergeri) and its hybridogenetic hybrid (P. kl. hispanicus). Members of this genus were recently found in certain sites in northern and southern Sardinia, and ascribed to the "ridibundus" group (the "Marsh frog" species complex). As the absence of clear phenotypic diagnostic features complicates the identification of distinct Pelophylax species, particularly European P. ridibundus, P. kurtmuelleri and several still undescribed "bedriagae" taxa, an informative diagnostic mitochondrial marker (ND3) was isolated in this work in order to detect the occurrence of distinct lineages in alien Sardinian populations. As water frogs are known to readily hybridize in the wild, two further diagnostic nuclear markers (SAI-1 and 4 microsatellite loci) were subsequently screened in order to exclude the occurrence of hybrid genotypes. According to our results, three distinct taxa were detected on the island, and assigned to P. kurtmuelleri (the Balkan frog), and two cryptic taxa of the "bedriagae" group. Nuclear markers only successfully amplified alleles diagnostic for the "ridibundus"-type (R) genome. Accordingly, we can exclude hybridization with the Italian pool frog already introduced on the island, although further studies are needed to better address the occurrence of new hybrid lineages stemming from the cross between the taxa detected in this work. As eggs and tadpoles have been detected in the field, alien populations can thus be considered successfully established in Sardinia. Our study revealed for the first time the occurrence of the alien Balkan frog in the western Mediterranean. It is worthy of note that this taxon shows a high invasion potential in mainland Europe. The establishment of alien Pelophylax populations in Sardinia may be favored by vacant niches. Nonetheless, the dry hot season could limit their expansion along rivers. [ABSTRACT FROM AUTHOR]

The effects of different concentrations of water-soluble fraction of crude oil (WSFO) from the Zhanazhol oil field (Aktobe region, Kazakhstan) and compared to o-xylene, prevalent in this oil, on growth and development of marsh frog (Rana ridibunda) were assessed. In subchronic experiments (7 d), a dose-related increase in mortality and incidence of deformities in embryos were observed. In chronic experiments (60 d; starting from the Gosner stage 26), a dose-dependent decrease in body weight, size and developmental delay by 3-4 stages were also detected. In addition, the content of lipid hyperoxide (LHO) and malondialdehyde (MDA), as well as activities of superoxide dismutase (SOD) and catalase (CAT) enzymes in liver of the tadpoles were determined at the end of chronic experiment. Exposure to 0.5 mg/L or 1.5 mg/L WSFO elevated the content of LHO by 76% and 86%, and MDA by 47% and 58% but decreased SOD activity by 26% and 49%, and CAT by 35% and 46%, respectively. A less pronounced adverse effect was found after chronic exposure to the same concentrations of o-xylene. In tadpole liver exposed to o-xylene levels of LHO was increased by 40% and 51%, MDA by 11% and 29%, while the activity of SOD was lowered by 18% and 41%, and CAT - by 13% and 37% in the 0.5 mg/L and 1.5 mg/L treatment groups, respectively. Data demonstrated the embryotoxic and teratogenic effects attributed to WSFO and o-xylene exposure which may involve oxidative stress mechanisms. [ABSTRACT FROM AUTHOR]

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Microplastics (MPs), which are of increasing concern in almost all ecosystems, continue to be an environmental threat. In the present study, the presence of MPs is investigated by using the gastrointestinal tracts (GITs) obtained from the true frog individuals sampled in the past years. The sample consists of a total of 146 individuals obtained from various regions of Türkiye. The results show that MPs were found in 87 adult frog individuals. The most predominant shape of MPs found was fiber, with a predominance of transparent color, and ethylene-vinyl acetate (EVA) was also the most abundant microplastic material. The highest amount of MPs among adult frog populations were found in the Denizli province. The size of MPs ranged between a minimum of 66 and a maximum of 3770 μm. In addition, no relationship was found between the body length and weight of the frogs and the sizes of MPs. Historically, most MPs were found in samples from 1990 and the highest content in terms of both color and material was detected in 1990. MPs were detected in almost all the years studied, but microplastic abundance varied from year to year. These results can be explained by the number of samples, habitat, and feeding behavior of adult frogs. [Display omitted] • For the first time, past patterns of microplastic pollution have been addressed in terms of amphibians. • The diversity of microplastics was greatest in 1990. • The most common form of microplastic, both in frog populations and across years, was fiber. • Ethylene-vinyl acetate (EVA) as microplastic type was the most abundant microplastic type. [ABSTRACT FROM AUTHOR]

The parasite fauna of lake frogs in the Ural region has been studied. 14 species of parasites belonging to Trematoda, Nematoda and Protozoa were found in the lake frog Pelophylax ridibundus in the South and Middle Ural. The parasitocenosis is characterized by a simplified structure while the number of infected animals increases with age. It was determined that the parasite species quantity in all age groups of P. ridibundus in the South Ural was higher than in the Middle Ural.

Several Brucella isolates have been described in wild-caught and “exotic” amphibians from various continents and identified as B. inopinata-like strains. On the basis of epidemiological investigations conducted in June 2017 in France in a farm producing domestic frogs (Pelophylax ridibundus) for human consumption of frog's legs, potentially pathogenic bacteria were isolated from adults showing lesions (joint and subcutaneous abscesses). The bacteria were initially misidentified as Ochrobactrum anthropi using a commercial identification system, prior to being identified as Brucella spp. by MALDI-TOF assay. Classical phenotypic identification confirmed the Brucella genus, but did not make it possible to conclude unequivocally on species determination. Conventional and innovative bacteriological and molecular methods concluded that the investigated strain was very close to B. microti species, and not B. inopinata-like strains, as expected. The methods included growth kinetic, antimicrobial susceptibility testing, RT-PCR, Bruce-Ladder, Suis-Ladder, RFLP-PCR, AMOS-ERY, MLVA-16, the ectoine system, 16S rRNA and recA sequence analyses, the LPS pattern, in silico MLST-21, comparative whole-genome analyses (including average nucleotide identity ANI and whole-genome SNP analysis) and HRM-PCR assays. Minor polyphasic discrepancies, especially phage lysis and A-dominant agglutination patterns, as well as, small molecular divergences suggest the investigated strain should be considered a B. microti-like strain, raising concerns about its environmental persistence and unknown animal pathogenic and zoonotic potential as for other B. microti strains described to date.