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Tonic immobility is an antipredator defence in which the prey animal remains motionless after physical contact with the predator, pretending to be dead. This behaviour has been observed among a variety of taxa but has received only little attention in amphibian larvae. During our field studies with fire salamander larvae, we observed that larvae from different habitats display tonic immobility after handling. In our study site, we find larvae in pond and stream habitats, that differ in several aspects such as their stress response and their risk‐taking behaviour, likely caused by the very different habitat conditions. We measured the time that the tonic immobility behaviour was displayed but found no difference between larvae from the two habitat types. Likewise, we also found no correlation between the size of the larvae and the duration of displaying the behaviour. In conclusion, we found that fire salamander larvae show tonic immobility, but found no evidence that the different habitat conditions influence the tonic immobility behaviour. [ABSTRACT FROM AUTHOR]

In this work, we evaluated the subchronic toxicity of FeSe nanoparticles (NPs) in tadpoles of Rana saharica. Tadpoles were exposed for 1–3 weeks to FeSe NPs at 5 mg/L and 100 mg/L rates. Parameters of oxidative stress were measured in whole larvae, and the micronucleus test was performed on circulating blood erythrocytes. We noted a disturbance of the detoxification systems. Enzymatic and non-enzymatic data showed that exposure to FeSe NPs involved a highly significant depletion of GSH, a significant increase in GST activity, and a lipid peroxidation associated with a highly significant increase in MDA. We also noted a neurotoxic effect characterized by a significant inhibition of AChE activity. A micronucleus test showed concentration-dependent DNA damage. This research reveals that these trace elements, in their nanoform, can cause significant neurotoxicity, histopathologic degeneration, cellular and metabolic activity, and genotoxic consequences in Rana larvae. [ABSTRACT FROM AUTHOR]

Facultative colour change is widespread in the animal kingdom, and has been documented in many distantly related amphibians. However, experimental data testing the extent of facultative colour change, and associated physiological and morphological implications are comparatively scarce. Background matching in the face of spatial and temporal environmental variation is thought to be an important proximate function of colour change in aquatic amphibian larvae. This is particularly relevant for species with long larval periods such as the western spadefoot toad, Pelobates cultripes, whose tadpoles spend up to six months developing in temporary waterbodies with temporally variable vegetation. By rearing tadpoles on different coloured backgrounds, we show that P. cultripes larvae can regulate pigmentation to track fine-grained differences in background brightness, but not hue or saturation. We found that colour change is rapid, reversible, and primarily achieved through changes in the quantity of eumelanin in the skin. We show that this increased eumelanin production and/or maintenance is also correlated with changes in morphology and oxidative stress, with more pigmented tadpoles growing larger tail fins and having an improved redox status. [ABSTRACT FROM AUTHOR]

Several aquatic sampling techniques are commonly used to detect and quantify amphibian larvae. Although many techniques have been standardized, comparisons among methods have been poorly studied. We employed a removal design to investigate the detection rate of amphibian larvae using box enclosures and evaluated the reliability of timed dipnet sampling relative to the more quantitative box enclosure sampling across 13 vernal pools. For these comparisons, we studied larvae of the endangered California Tiger Salamander (Ambystoma californiense; CTS) and the smaller and more abundant tadpoles of the Pacific Treefrog (Pseudacris regilla; PTF). Based on N-mixture model estimates, box enclosure sampling captured only 5% more of the CTS larvae present than PTF tadpoles, despite disparities in their sizes and estimated abundances. Dipnet sampling was slightly more effective at detecting CTS larvae than was enclosure sampling, while both methods equally detected PTF tadpoles. We found a strong relationship (R2 = 0.92) between the densities of CTS larvae estimated from dipnet sampling and those calculated from the more quantitative enclosure sampling, indicating that dipnet sampling is a reliable measurement of relative abundance. We conclude that timed dipnet surveys can be an important tool for monitoring populations of CTS, and possibly other lenticbreeding amphibians, especially given its relative efficiency that can be replicated across both time and space. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are threatened by climate change and invasive species. Amphibians are important members of freshwater communities and are susceptible to negative effects of climate change and invasion. Furthermore, both climate change and invasion can influence density of amphibian larvae at the microhabitat scale because of larval clustering. To understand the effects of climate change and invasion on Pacific Chorus Frog Pseudacris regilla (Baird and Girard, 1852) larvae, a 2 × 2 × 2 factorial experiment was carried out with a climate treatment (future/historical; simulated as changes in both temperature and hydroperiod), indirect exposure to the invasive Brook Stickleback Culaea inconstans (Kirtland, 1840) fish (chemical cues present/absent), and conspecific density (conspecific present/absent). We measured tadpole survival and development rate along with variables related to body shape, including mass, growth, growth rate, body mass index, tail fin depth, tail muscle depth, tail muscle width, and rear limb length. We assessed the effects of 3 common and important stressors (climate, invasive species, and density) alone and in combination with the other stressors to explore their interactions. Climate change, as simulated by our study, had large effects on Pacific Chorus Frog tadpole development and body shape. Brook Stickleback chemical cues had smaller but important effects on body shape and development rate when combined with additional stressors. Competition because of presence of a conspecific tadpole also reduced survival and had large effects on body shape. Pairwise interactions were largely additive or antagonistic. Three-way stressor interactions were most often antagonistic, resulting in less-than-additive effects of the 3 stressors together. However, 3 synergistic 3-way emergent interactions were detected. When all 3 stressors were present, development rate was faster than expected but rear limb length and tail muscle width were smaller than expected. Our results illustrate that climate change and conspecific density have wide-ranging effects on amphibian growth, development, and morphology—effects which may carry over into the terrestrial stage and reduce fitness. Furthermore, our findings reveal complex stressor interactions that were not predictable from single stressor effects or pairwise stressor effects, illustrating the difficulty in predicting multiple stressor interactions in freshwater systems. [ABSTRACT FROM AUTHOR]

Monensin, an antibacterial commonly used in animal fattening, can enter aquatic ecosystems and harm non-target organisms. Since there are no previous studies about the effects of monensin on amphibians, the aim of the present study was to evaluate the lethal and sublethal toxicity of a commercial formulation of monensin (CFM) through standardized bioassays with embryos and larvae of the amphibian Rhinella arenarum. Oxidative stress (catalase and glutathione S-transferase activities, and reduced glutathione and lipid peroxidation levels), cholinesterasic effect (acetylcholinesterase and butyrylcholinesterase activities) and mutagenicity (micronuclei frequency) biomarkers were evaluated. The CFM produced teratogenic effects, with a teratogenic index of 6.21. Embryos (504 h-LC50: 273.33 µg/L) were more sensitive than larvae, as no significant mortality was observed on larvae exposed up to 3000 µg/L for 504 h. However, oxidative stress, cholinesterasic effect and mutagenicity biomarkers were altered on larvae exposed for 96 h to environmentally relevant concentrations (4, 12 and 20 µg/L of monensin active ingredient). The CFM caused adverse effects on the exposed organisms, primarily on embryos, leading to lethal and sublethal effects, which could impact the wildlife when it reaches aquatic ecosystems. • Mortality was stage and time dependent, with embryos being more sensitive. • Monensin produced teratogenicity for Rhinella arenarum embryos. • Oxidative stress and neurotoxicity biomarkers were altered at low concentrations. • Environmental concentrations caused genotoxicity. • The risk quotient indicated a risk of adverse effects on aquatic organisms. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr [VI]) is one of the major detrimental heavy metal pollutants. In the present study, Bufo gargarizans were exposed to 0, 52, 104, 208, and 416 μg/L Cr (VI) from Gosner stage 2 until metamorphosis; and growth, development, and histological characteristics of the thyroid gland and skeletal ossification were examined. The results demonstrated that the survival rate of larvae exposed to Cr (VI) was not different from that measured in animals from the control group. However, high levels of Cr (VI) (104, 208, and 416 μg/L) were associated with significantly delayed growth and development. The suppression of skeletal ossification was observed at high Cr (VI) levels. Besides, histological alterations of the thyroid gland, such as follicular cell hyperplasia, colloid depletion, and peripheral colloid vacuolation, were found in 52 to 416 μg/L Cr (VI) treatments. The results of the present study highlight reductions in growth and development as well as percent metamorphosis and skeletal ossification due to histological alteration of the thyroid gland during exposure to Cr (VI) in B. gargarizans larvae. The present investigation could provide a basis for understanding the detrimental effects of Cr (VI) in amphibian larvae. Environ Toxicol Chem 2021;40:2474–2483. © 2021 SETAC [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]

Changes in phenology are among the most pervasive effects of current climate change. Modifications in the timing of life‐cycle events can affect the behavior, physiology and life‐history of wildlife. However, organisms can develop compensatory strategies in order to reduce the costs of phenological alterations. Here, we examine the extent and limits of compensatory developmental responses in amphibian larvae exposed to variation in hatching timing. Using a common‐garden experiment, we analyze how changes in temperature and food conditions alter compensatory responses to hatching delay, paying particular attention at how adverse environmental conditions can constrain these responses. We found that under benign conditions (warm temperature, unrestricted food) larvae fully compensate for the hatching delay, without cost in mass. However, under detrimental conditions (cold temperature and restricted food) these responses were prevented, and the combination of adverse conditions with long hatching delay completely disrupt compensatory responses. This study highlights the need of examining ecological responses to climate variation across a broad spectrum of environmental conditions in order to accurately predict the putative effect that climatic alterations can have on the life‐histories and survival of wildlife. [ABSTRACT FROM AUTHOR]

Urodelan amphibian larvae develop three pairs of branching external gills on both sides of the pharyngeal region, and this study focuses on motile cilia on the gill surface. High-speed camera was used to observe ciliary strokes on the surface of the external gills of Pleurodeles waltl larvae. We found that the directionality of ciliary beating is position-dependent on the gill surface, and this rule is applicable to all the samples examined. For visualizing water flow around the external gills, we used bead suspensions. We revealed continuous anterior-to-posterior water flow generated by coordinated ciliary beating. Around the frontal surface of the gill stem (gill rachis), water flows countercurrent to the bloodstream beneath the gill epidermis. These results suggest that ciliary beating in each ciliated cell is coordinated, which cooperatively generates continuous and directional ciliary flow. We next visualized the overall distribution of ciliated cells on the gill surface by immunostaining of acetylated alpha-tubulin. Our results showed that the fine branches of external gills (fimbriae) have a circumferential distribution of cilia aligned orthogonal to the longitudinal axes of fimbriae, which facilitates water flow from proximal to the distal part of the fimbriae through the gills. This ciliary distribution pattern and directionality of cilia-driven flow are shared among five urodelan and two anuran species. Taken together, our findings suggest that the distribution and motility of ciliated cells on the surface of external gills is finely controlled, and this might support efficient respiration by the gills in urodeles. [ABSTRACT FROM AUTHOR]

Species habitat range is partly determined by interspecies interactions between phylogenetically related species. Siberian salamanders are widely distributed across the Eurasian continent and occupy various habitats, but in Hokkaido island, Japan, it is restricted to only two regions. For the restricted habitat range of Siberian salamanders in Hokkaido, we hypothesized that Ezo salamander, whose larvae heavily consume amphibian larvae, excludes Siberian salamander from their range by the predation during the larval period. Here, we investigated the potential interaction between Siberian and Ezo salamander larvae in an aquarium experiment. As expected, in the cases where they cohabit, all Siberian salamander larvae were immediately killed by Ezo salamander larvae through predation. Although the predation enhanced individual growth of Ezo salamander larvae, it may not merely increase the fitness of Ezo salamander larvae. Interestingly, in the presence of Siberian salamanders, cannibalism occurred more frequently in Ezo salamanders, even though it only occurred in limited replications, probably as a result of improving growth and increasing size variation among Ezo salamander larvae. [ABSTRACT FROM AUTHOR]

Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungus Batrachochytrium dendrobatidis (Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before exposure to Batrachochytrium dendrobatidis (Bd) alters susceptibility to the disease chytridiomycosis in the larval stage of two amphibian species–western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15° C) temperature in comparison to constant warm (20° C) temperature. Additionally, both species experienced an increase in Bd infection abundance after shifted from 15° C to 20° C, compared to a constant 20° C but they experienced a decrease in Bd after shifted from 20° C to 15° C, compared to a constant 15° C. These results are in contrast to prior studies of adult amphibians highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis. [ABSTRACT FROM AUTHOR]

Replacing chair fungicide racemate marketed product by its enantiomer with high activity and low environmental risk for application is a more environmentally friendly methods to control crop diseases. Moreover, carbon-based nanomaterials, with the desirable chemical and mechanical properties, exhibits latent reduce fungicide toxicity capability, while the mechanism is still poorly understood. Therefore, the present study characterized the toxicity of rac -metconazole (Mez; (1 RS ,5 RS ;1 RS ,5 SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(1H)) and its two cis -enantiomers as well as the repairing effect of reduced graphene oxide (rGo) on Xenopus Laevis larva by examining growth appearance indexes, Mez bioaccumulation, and hypothalamus-pituitary-thyroid (HPT) axis related hormone contents and gene expression after 14 and 28 days exposure. Compared with two cis -Mez, rac -Mez was preferentially bioaccumulated in tadpoles, and rac -Mez treatment showed a higher toxicity effect on tadpole including growth stage and body weight inhibition by dysregulating tadpole thyroid stimulating hormone (TSH) and thyroid hormone (TH) contents and related gene expression. Enantioselectivity was observed in two cis -Mez treatments. Compared with R , S -Mez, S , R -Mez treatment showed more severe damage on tadpole HPT axis related physiological and biochemical processes. rGo could effectively decrease the toxicity of Mez, especially shown the capacity of repairing the hormone dysregulation caused by R , S -Mez treatment. Moreover, the addition of rGo can decrease the bioaccumulation of Mez in tadpoles. Therefore, R , S -Mez is less toxic to Xenopus Laevis larva growth, and its toxicity could be effectively repaired by the addition of rGO. Reduced graphene oxide could effectively repair the inhibition of TSH content and Dio2 activity caused by Metconazole, then regulated HPT related hormone and gene expression back to the normal level. [Display omitted] • rac- metconazole was preferentially bioaccumulated in tadpoles. • Endocrine disruption of metconazole on amphibian larva was observed. • R , S -metconazole exhibited lower inhibition on tadpole growth than others. • rGo could effectively decrease the bioaccumulation and toxicity of metconazole in tadpoles. [ABSTRACT FROM AUTHOR]

Concerns about the implications of microplastics (MPs) on aqueous animals have gained widespread attention. It has been postulated that the magnitude of MPs can influence its toxicity. However, little is known about how MPs toxicity changes with particle size. Amphibians are reliable bioindicators of ecosystem health due to their complex life cycles. In this study, we compared the influences of two sizes nonfunctionalized polystyrene microspheres (1 and 10 μm) on the metamorphosis of Asiatic toad (Bufo gargarizans). Acute exposure to MPs at high concentrations led to bioaccumulation in the digestive track and internal organs (i.e., liver and heart) of tadpoles. Long-term exposure to either size, at environmentally-related concentrations (1 and 4550 p/mL), led to growth and development delay in pro-metamorphic tadpoles. Remarkably, developmental plasticity mitigated these deleterious effects prior to the onset of metamorphic climax without compromising survival rate in later stages. MPs with a diameter of 10 μm dramatically altered the gut microbiota (e.g., abundance of Catabacter and Desulfovibrio) of pro-metamorphic tadpoles, whereas MPs with a diameter of 1 μm induced much more intensive transcriptional responses in the host tissues (e.g., upregulation of protein synthesis and mitochondrial energy metabolism, and downregulation of neural functions and cellular responses). Given that the two MPs sizes induced similar toxic outcomes, this suggests that their principal toxicity mechanisms are distinct. Small-sized MPs can travel easily across the intestinal mucosa and cause direct toxicity, while large-sized MPs accumulate in gut and affect the host by changing the homeostasis of digestive track. In conclusion, our findings indicate that MPs can affect the growth and development of amphibian larvae, but their developmental plasticity determines the ultimate detrimental effects. Multiple pathways of toxicity may contribute to the size-dependent toxicity of MPs. We anticipate that these findings will increase our understanding of the ecological effects of MPs. [Display omitted] • Both 1 and 10 μm MPs affect the growth and development of pro-metamorphic tadpoles. • Developmental plasticity offsets the effects of MPs before metamorphic climax. • Differently-sized MPs impact host tissues and symbiotic microbiota discriminately. • Large-sized MPs mainly affect the diversity and function of gut symbiotic microbiota. • Small-sized MPs mainly target host tissues and affect mitochondrial and neural functions. [ABSTRACT FROM AUTHOR]

The composition and diversity of biotic assemblages is regulated by a complex interplay of environmental features. We investigated the influence of climate and the aquatic habitat conditions on the larval traits and the structure of amphibian larval guilds in north-western Africa. We classified the species into morphological groups, based on external traits: body shape, size, and the relative positions of the eyes and oral apparatus. We characterized the guild diversity based on species richness and interspecific phylogenetic/functional relationships. The larvae of the urodeles were classified as typical of either the stream or pond type, and the anurans as typical of either the lentic-benthic or lentic-nektonic type. The variations in the body shapes of both urodeles and anurans were associated with the type of aquatic habitat (lentic vs lotic) and the types of predators present. Most of the urodele guilds (98.9%) contained a single species, whereas the anuran guilds were usually more diverse. Both the phylogenetic and functional diversity of the anuran guilds were positively influenced by the size of the aquatic habitat and negatively by aridity. In anurans, the benthic and nektonic morphological types frequently co-occurred, possibly influenced by their opportunistic breeding strategies. [ABSTRACT FROM AUTHOR]

Foraging theory suggests organisms increase their fitness through dietary and energetic choices. In nature, organisms choose to consume balanced optimal diets but as exotic plants invade ecosystems, new foraging options become available. Often these plants have different traits and can negatively affect fitness of foragers by lowering survival or growth due to toxicity. Wetland habitats are highly susceptible to plant invasions which can have negative effects on nutrient cycling. The purpose of this study was to examine whether invasion of purple loosestrife (Lythrum salicaria) alters tadpole foraging preference thus potentially impacting their survivorship and fitness. We designed a common garden experiment and utilized stable isotopic signatures to investigate the contribution of purple loosestrife and native hardwood detritus to larval wood frog (Rana sylvatica) and southern leopard frog (Rana sphenocephala) diets. Tadpoles derived a higher percentage of resources from purple loosestrife compared to native hardwood detritus when presented with both options, despite its high concentration of toxic secondary compounds. It is unknown if tadpoles can detect competing fitness signals that may be associated with higher nutrient and toxicity levels in purple loosestrife. Discovering the presence or absence of such signals will promote a greater understanding of selective foraging in changing environments. [ABSTRACT FROM AUTHOR]

ABSTRACT Amphibian metamorphosis is complex and larval morphology and physiology are completely restructured during this time. Amphibians that live in unpredictable environments are often exposed to stressors that can directly and indirectly alter physiological systems during development, with subsequent consequences (carryover effects) later in life. In this study, we investigated the effects of water level reduction on development rate, spleen size and cellularity, and examined the role of corticosterone levels in premetamorphic, metamorphic, and postmetamorphic New Mexico spadefoot toads ( Spea multiplicata). Based on previous studies, we hypothesized that declining water level would increase tadpole developmental rate, but with the trade-off of increasing corticosterone to a level that would subsequently affect spleen size and cellularity, thus prolonging potential immunological suppression. Declining water levels increased developmental rate by 3 days; however, there were no significant body size effects. Corticosterone (CORT) was negatively correlated with total length, snout vent length, body weight, and spleen weight at metamorphosis, suggesting that size at metamorphosis and the immune system may be affected by excessive CORT levels. When compared to other studies, our results support the view that multiple factors may be acting as stressors in the field affecting amphibian responses, and simple pathways as tested in this study may not adequately represent field conditions. [ABSTRACT FROM AUTHOR]

Habitat degradation is a contributory factor to poor recruitment and sustainability of the European native oyster, Ostrea edulis. Bed cleaning (harrowing) is a widely referenced but little studied habitat management measure aimed at exposing clean shell for oyster larvae to settle upon. This study carried out a large-scale field experiment in Lough Foyle on the border of Northern Ireland and Ireland over 3 years aimed at investigating the effects of harrowing on oyster spat settlement, substratum condition, suspended particulate matter and associated faunal assemblage. The results demonstrated that O. edulis spat settlement was higher in unharrowed areas and there was no significant difference in bivalve settlement between the two treatments. Harrowing had no significant effect on percentage cover of fouling organisms, but there was a significant difference between assemblages in harrowed and unharrowed treatments. This study concluded that harrowing is not suitable for all oyster production areas and should only be employed with caution. [ABSTRACT FROM AUTHOR]

This paper describes the external and buccal cavity morphology, chondrocranium, hyobranchial apparatus and cranial muscles of Alsodes neuquensis in comparison with the sibling species A. gargola. The tadpole of A. neuquensis presents a shorter and higher tail, and a relatively smaller oral disc than A. gargola. The external larval morphology of Alsodes may be characterised as follows: (i) tooth row formula 2(2)/3(1), (ii) single row of marginal papillae with a wide rostral gap, (iii) single row of submarginal papillae in the mental region, (iv) both supra- and infraangular submarginal papillae present. The buccal features do not show marked intrageneric differences. The anterior and/or posterior pair of infralabial papillae may be simple or forked. All known tadpoles present one prenarial papilla accompanied or not by few pustules, and the lateral ridges of floor can be three to penta-armed. The chondrocranial features shared by the species of the genus Alsodes are (i) tetrapartite cartilage suprarostralis, (ii) chondrified adrostral tissue mass, (iii) processus anterolateralis of the larval crista parotica well developed or larval processus oticus, and (iv) large processus pseudopterygoideus that may be either completely fused to the basi cranii (A. vanzolinii, A. verrucosus and some A. neuquensis) or fused only at the tip (A. barrioi, A. gargola and some A. neuquensis). Larval cranial muscles are for the first time described for the genus Alsodes. They do not show differences between both species studied herein. [ABSTRACT FROM AUTHOR]

Conservation breeding programmes are increasingly needed for amphibians given the ongoing amphibian extinction crisis, yet key aspects of husbandry such as larval diet remain understudied and in many cases completely unknown. In Madagascar, enacting such programmes can also be challenging due to the unavailability of diets designed specifically for tadpoles. We tested three diets locally available in Madagascar -- mustard greens, spirulina algae, and atyid shrimp -- on the larvae of Mantidactylus betsileanus and recorded their growth and development. Tadpoles fed mustard greens took longer to develop and completed metamorphosis at a smaller size. No difference was found in the survival of tadpoles between treatments. These results suggest that mustard greens are a poor food source for rearing M. betsileanus and similar species. Instead, spirulina and atyid shrimp should be used, although other alternatives such as commercially manufactured tadpole and fish foods might yield even better results. [ABSTRACT FROM AUTHOR]

We compare diet and feeding behaviour of Snapping Turtles (Chelydra serpentina) and Midland Painted Turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles feeding on insect and amphibian larvae in ephemeral ponds, adult Chrysemys terrestrially foraging on odonate larvae, and adult Chelydra consuming aquatic vegetation and seeds. These and other observations highlight the importance of seasonally available habitat and food for juvenile turtles. We also discuss the evidence for, and importance of, turtles as seed-dispersal agents for aquatic vegetation. Illustrative video recordings accompany our dietary observations. [ABSTRACT FROM AUTHOR]

We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt ( Taricha granulosa ). We assigned newt eggs to different temperatures (7, 14, or 21 °C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the reduction and development of the dark-sided frog Hylarana nigrovittata sensu in at the Cologne Zoo in northern Thailand. The study involves identification of oviposition which occurred in accordance with dried natural habitat, along with the Important factor to increase the reproduction in captivity, such as an increase in misting with combined raised water levels. Results show the molecular divergence and morphological differences regarding the captive breeding and development stages of the dark-sided frog.

Abstract: Organophosphate (OP) and carbamate pesticides are anticholinesterasic agents also able to alter antioxidant defenses in different organisms. Amphibian larvae are naturally exposed to these pesticides in their aquatic environments located within agricultural areas. We studied the effect of the carbamate carbaryl (CB) and the OP azinphos methyl (AM), compounds extensively used in Northern Patagonian agricultural areas, on reduced glutathione (GSH) levels and the activities of esterases and antioxidant enzymes of the toad Rhinella arenarum larvae. Larvae were exposed 48h to AM 3 and 6mg/L or CB 10 and 20mg/L. Cholinesterase and carboxylesterases were strongly inhibited by CB and AM. In insecticide-exposed larvae, carboxylesterases may serve as alternative targets protecting cholinesterase from inhibition. GSH-S-transferase (GST) activity was significantly increased by CB and AM. Superoxide dismutase activity increased in tadpoles exposed to 6mg/L AM. Conversely, catalase (CAT) was significantly inhibited by both pesticides. GSH levels, GSH reductase and GSH peroxidase activities were not significantly affected by pesticide exposure. GST increase constitutes an important adaptive response to CB and AM exposure, as this enzyme has been related to pesticide tolerance in amphibian larvae. Besides, the ability to sustain GSH levels in spite of CAT inhibition indicates quite a good antioxidant response. In R. arenarum larvae, CAT and GST activities together with esterases could be used as biomarkers of CB and AM exposure. [ABSTRACT FROM AUTHOR]

The newt larvae (Pleurodeles waltl) stage 48-49 in the development table of Gallien and Durocher (1) were exposed for 30 days to sediment previously contaminated with individual 14 C-labeled polycyclic aromatic hydrocarbons (PAHs), including anthracene (Ant), phenanthrene (Phe), pyrene (Pyr), and benzo[ a ]pyrene (B a P). Toxicokinetic parameters (uptake and depuration rate constants) were measured. The rate of radioactivity release was measured under both contaminated (Experiment 1) and clean conditions (Experiment 2). The results confirmed that uptake and depuration rate constants were strongly related to physicochemical properties including the number of rings, molecular weight, octanol-water coefficient partition ( K OW ), and water solubility. The highest uptake rate was observed with a low-molecular-weight compound (Ant). Comparatively the uptake rates for Phe, Pyr, and B a P were 17%, 48%, and 95% respectively, all lower than that for Ant. The rank order of PAH depuration rate constants from P. waltl was Phe > Ant > Pyr > B a P under both clean and contaminated conditions. The results also indicate that the depuration rate constants seemed to depend on the PAHs' bioavailability potential and their initial concentration in larvae at the beginning of the depuration phase. Thus when the initial concentration of pollutants in the animal were very weak (example: B a P), the depuration rate constants were in the same range for Experiments 1 and 2. In contrast when the PAHs' initial bioconcentrations were relatively high like for Ant, Phe, and B a P, their elimination from the larvae remained from 1.5-fold to 2-fold faster under Experiment 1 than under Experiment 2. [ABSTRACT FROM AUTHOR]

The article focuses on a research study which analysed the difference in hydroperiod length, fish presence or absence and larval amphibian assemblage structure, amongst larval amphibians and fish in different locations in South Carolina. It states that it was found that wetlands which contained water for longer periods, contained high number of fishes and low amphibian species.

In nature, animals often face periods without food caused by seasonal fluctuations and/or prey scarcity. An organism's physiological response to imposed energetic limitations is followed by changes in mitochondrial functioning (adjustment of energy metabolism) and a reduction of non-essential processes. However, this energy-saving strategy can have its costs. In this study, we examined oxidative stress as one of the possible physiological costs of short-term, two-week-long food deprivation on developing amphibian larvae of the crested newts Triturus macedonicus and Triturus ivanbureschi and their hybrids. We investigated whether this exogenous factor additionally affected the oxidative status (fitness-related trait) of hybrid individuals. The fasting treatment led to lower growth and a lower body mass and body condition index of individuals. The results revealed that the antioxidant system (AOS) of food-deprived larvae could not cope in a proper manner with reactive oxygen species production under limited energy availability, leading to higher lipid oxidative damage. The lowest AOS response was observed for H 2 O 2 scavenging parameters (catalase, glutathione peroxidase, and total glutathione), which together with the elevated activity of superoxide dismutase suggested increased H 2 O 2 concentrations. Comparison between parental species and their hybrids showed that hybrid individuals suffered greater oxidative damage (as demonstrated by higher concentrations of lipid peroxides), indicating that they were more susceptible to fasting-induced oxidative stress. Overall, this study illustrates that: (i) an oxidative event is one of the costs amphibian larvae face during short-term periods of fasting, (ii) hybrids are less capable of dealing with this stressful condition, which can lower their chances of survival in a changing environment. Unlabelled Image • Two weeks of fasting lead to an oxidative stress situation in crested newt larvae. • Fasting individuals showed a decreased antioxidant response (CAT, GSH-Px, GSH). • Food deprivation in larvae increased oxidative damage (LPO). • Hybrids had a higher concentration of lipid peroxides than parental species. • Oxidative stress is one of the costs of fasting in amphibian larvae. [ABSTRACT FROM AUTHOR]

Simple Summary: A lack of adequate refuge, even in the absence of predators, can alter the metabolism, levels of corticosteroids, growth and behavior in various groups of animals. Even though some of those processes (higher metabolic rates and activation of the stress response of the hypothalamic-pituitary-adrenal axis) in animals can result in enhanced reactive species (RS) production and oxidative stress, there is no study examining the effects of shelter on oxidative stress parameters. The results from this study showed that in crested newt larvae the absence of refuges altered their oxidative/antioxidative status and movement, but did not affect their aggressivity/injuries rate. Higher values of catalase, glutathione peroxidase, glutathione S-transferase and glutathione can indicate increased production of hydrogen peroxide in individuals without an adequate hiding place. This boosted antioxidant defense has a certain physiological cost that can be expressed in terms of the consumption of energy needed to maintain it as upregulated. Shelters are important for animal survival. Provision of adequate hiding places allow animals to express their natural sheltering behavior and it can have different positive effects on cortisol levels, physiological processes and mental performance. Although the absence of a refuge activates some stress response, its effect on oxidative stress has not been adequately examined. This study investigated whether the presence/absence of a shelter modifies the oxidative status (the antioxidant system and oxidative damage) and aggressive behavior of crested newt larvae (Triturus macedonicus and its hybrid with T. ivanbureschi). Our results show that individuals reared with shelters had lower values of the tested antioxidant parameters (catalase, glutathione peroxidase, glutathione S-transferase and glutathione), indicating a lower production of reactive species than individuals reared without shelter. The same pattern was observed in both T. macedonicus and its hybrid. Contrary to the activation of some physiological pathways, shelter availability did not significantly affect the rate of intraspecific aggressive behavior. The physiological benefits of shelter use can be manifested as a lower requirement for investment in the energy necessary for the maintenance of the upregulated antioxidant defenses, activation of repair systems and synthesis of endogenous antioxidants. This study highlights the importance of shelter provision, which may be valuable in habitat restoration and animal conservation studies. [ABSTRACT FROM AUTHOR]