Effects of triphenyltin and pH on the growth and development of Rana lessonae and Rana esculenta tadpoles

Abstract

We tested the s sceptibility of parental (Rana lessonae) and hemiclonal hybrid tadpoles of the R. esculenta complex to triphenyltin (TPT), a fungicide commonly used in agriculture, at renewed concentrations of 0.11, 0.81, and 1.87 μg/L over the entire larval period. Because habitats of R. lessonae are often characterized by a low pH and disturbed habitats such as gravel pits by high pH, we also tested whether pH 6.4 or pH 8.1 modifies their susceptibility to triphenyltin. We measured survival to metamorphosis, body mass at day 30, body mass at metamorphosis, and time to metamorphosis of individually reared tadpoles. Crosses of R. lessonae males with R. lessonae females and with two hemiclones of R. esculenta females produced tadpoles of R. lessonae, R. esculenta (GUT1) and R. esculenta (GUT2). At increasing triphenyltin concentrations, survival and growth rate decreased and time to metamorphosis increased. The GUT1 larvae of R. esculenta were the least and larvae of R. lessonae the most sensitive. The GUT2 larvae of R. esculenta were intermediate in sensitivity. The effect of pH also depended on the genotype. Tadpoles of R. lessonae had a higher growth rate and a shorter larval period at pH 6.4. The pH effect on tadpoles of R. esculenta was slight, but growth rate was lower and larval period longer at pH 6.4. Because TPT most strongly affected the larval period, exposure to TPT could decrease survival in natural ponds because of the increased risk of predation in permanent ponds or desiccation in drying ponds as well as the increased risk of additional chemical exposure. Our results indicate that the sexual parental species R. lessonae is more sensitive to environmental chemicals such as triphenyltin than is the hemiclonal hybrid R. esculenta.

Spontaneous heterosis in larval life-history traits of hemiclonal frog hybrids

“…Such R. esculenta have faster larval growth (68)(69)(70), regularly reach metamorphosis earlier (35,69,71; L. Berger, personal communication), are more efficient feeders (36), and have higher resistance to hypoxic conditions of hibernation after metamorphosis (37) than either parental species. Relative to their sexual host R. lessonae, R. esculenta tadpoles also produce more metamorphs in harsh conditions of drying ponds and interspecific competition (33), have higher survival and earlier metamorphosis under resource-limited conditions (49), survive better in the presence of larval dragonfly predators (72), and are less sensitive to the common agricultural fungicide triphenyltin in survival, growth rate, and time to metamorphosis (38). Moreover, R. esculenta females were found to have a higher fecundity and produce more eggs per unit body mass than either parental species, outperforming females of the sexual host R. lessonae in mean fecundity by a factor of three (73).…”

“…Metamorphosed R. esculenta are more tolerant to hypoxic conditions than either parental species (37). In addition, R. esculenta tadpoles are more tolerant to a common agricultural fungicide (TPT, triphenyltin chloride) than R. lessonae tadpoles (38). These findings together suggest a broader environmental tolerance of the hybrid R. esculenta relative to its parental species, yet in most of these studies, R. esculenta was treated collectively, without resolving hemiclone identity.…”

Bioconcentration and bioavailability of organotin compounds: Influence of pH and humic substances

“…With respect to the ecotoxicology of organotin compounds, many studies have been performed on the contamination of aquatic systems and the toxicity. [1][2][3][4][5][6][7]14,15 Knowledge has also been gained on the distribution pattern of organotins in environmental compartments. 12,[16][17][18][19] However, the longterm ecotoxicological effects of organotin contaminants on the structure and function of aquatic ecosystems are still not well understood, particularly with respect to biomagnification in food webs 12,[20][21][22] and toxicity of contaminated sediments.…”

Assessment of hormonal activity of UV filters in tadpoles of frog Xenopus laevis at environmental concentrations

“…Antithyroid and thyroid-mimicking substances can be detected through delayed or enhanced metamorphosis resulting in lower or higher developmental stages, respectively (Fioramonti, Semlitsch, Reyer, & Fent, 1997;Goleman et al, 2002). Therefore developmental stage, whole body and tail length of the tadpoles were determined in our experiments for possible effects of UV filters on metamorphic development, growth rate and tail resorption.…”