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Title (Primary) Mass anomalies in green toads (Bufotes viridis) at a quarry in Roßwag, Germany: inbred hybrids, radioactivity or an unresolved case?
Title (Secondary) Studies on anomalies in natural populations of amphibians = Untersuchungen zu Anomalien in natürlichen Populationen von Amphibien
Author Henle, K.; Dubois, A.; Rimpp, K.; Vershinin, V.L.;
Publisher Henle, K.; Dubois, A.;
Journal Mertensiella
Year 2017
Department NSF;
Volume 25 (Suppl. zu Salamandra)
Language englisch;
POF III (all) T12;
Keywords Anura: Bufonidae: Bufotes viridis; Germany; chemicals; genetic causes; hybridization; inbreeding; mass anomalies; radioactivity; teratogenetic causes
UFZ wide themes RU1;
UFZ inventory Leipzig, Bibliothek, Hauptlesesaal, 00521048, 17-0740 DK: 597.6 Stu
Abstract Amphibian anomalies have attracted human curiosity for centuries and the literature on this issue is very extensive. The vast majority of publications on natural populations refer to less than ten affected individuals. Recent observations of mass anomalies in amphibians and increased environmental awareness reignited the interest in amphibian anomalies as potential indicators of environmental perturbations and triggered concerns about environmental conditions and human health. A particularly severe case of mass anomalies in a natural amphibian population was discovered in a quarry close to the village of Roßwag in southern Germany in 1980. Until now, only very brief preliminary data have been published on this case and the cause(s)
of the anomalies have remained controversial. Here we provide a detailed account of the anomalies observed and on the studies undertaken to assess the potential cause(s). Based on an extensive literature review on experimentally induced anomalies in amphibians, we evaluate all known causes of amphibian anomalies as potential explanations for the observations in Roßwag.
At least 245 recently metamorphosed individuals and 1,000–2,500 tadpoles of the green toad (Bufotes viridis) exhibited anomalies, thus scoring fourth highest among the 2782 cases from natural populations compiled by us for which concrete data were available. Thirty-two different types of anomalies were observed, which exceeded the next extreme case known (25 types of anomalies in a population of Rana arvalis that was exposed to a nuclear accident; 2990 cases with data available). Therefore, the
anomalies observed clearly do not represent a normal natural occurrence. The green toad was the only species spawning in the pond and, with the exception of three white clutches of the same species in a neighbouring quarry, no anomalies were found in any other population of amphibians in the vicinity of the quarry.
Based on an evaluation of results from 1025 publications of experimental studies, we show that all potential non-genetic factors taken together could at most explain a fraction of the observed types of anomalies, except for a cocktail of chemicals. Only one individual with a squashed head can be attributed with certainty to a non-genetic cause: traumatism. Chemical analyses of water samples from the breeding pond revealed a copper concentration at a level at which it might cause bent tails and edema in tadpoles. The water samples did not provide any other indication of chemical pollution and no pesticides were detected in abnormal toads. Notwithstanding, pesticides aerially sprayed on neighbouring vineyards might have contaminated the breeding pond well before water samples were taken.
The appearance of various anomalies in tadpoles and recently metamorphosed individuals raised from eggs transferred to the laboratory indicates that several types of anomalies were of genetic origins. The successful breeding of one abnormal individual verified this for one colour anomaly. Inbreeding, hybridization, as well as radioactivity and other mutagenic factors can explain genetically-based anomalies. Hybridization followed by inbreeding was put down as one explanation resulting from an official inquiry. However, genetic and morphological analyses as well as amphibian surveys conducted in the area of Roßwag clearly contradict hybridization as a potential cause. The great interindividual variability and high number of different types of
anomalies are not compatible with inbreeding as an explanation. No evidence of mutagenic chemicals was found, though it cannot be excluded with absolute certainty that such substances had been present but were already degraded at the time of chemical sampling. In contrast, high levels of radioactivity were measured at the opening of cracks at a deposit of earth bordering the breeding pond. Alerted officials rejected these measurements as artefacts but did not take any measurements at the opening of cracks. Here it is shown that all radioactivity measurements are consistent with one another and with the hypothesis of radioactive
material being burrowed in the deposit of earth and accessible to toads via cracks. This hypothesis is the only explanation that is consistent with all observations and measurements taken and with the results from a huge body of literature on experimental studies. There is no evidence for any other potential cause for the anomalies and biological knowledge clearly contradicts all of them with the exception of mutagenic substances.
ID 19688
Persistent UFZ Identifier http://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=19688
Henle, K., Dubois, A., Rimpp, K., Vershinin, V.L. (2017):
Mass anomalies in green toads (Bufotes viridis) at a quarry in Roßwag, Germany: inbred hybrids, radioactivity or an unresolved case?
In: Henle, K., Dubois, A. (eds.)
Studies on anomalies in natural populations of amphibians = Untersuchungen zu Anomalien in natürlichen Populationen von Amphibien
Mertensiella 25 (Suppl. zu Salamandra)
Deutsche Gesellschaft für Herpetologie und Terrarienkunde (DGHT), Mannheim, p. 185 - 242