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Parasite (Ribeiroia ondatrae) infection linked to amphibian malformations in the western United States
journal contribution
posted on 2002-05-01, 00:00 authored by P T J Johnson, K B Lunde, E M Thurman, Euan RitchieEuan Ritchie, S N Wray, D R Sutherland, J M Kapfer, T J Frest, J Bowerman, A R BlausteinParasites and pathogens can influence the survivorship, behavior, and very structure of their host species. For example, experimental studies have shown that trematode parasites can cause high frequencies of severe limb malformations in amphibians. In a broad-scale field survey covering parts of California, Oregon, Washington, Idaho, and Montana, we examined relationships between the frequency and types of morphological abnormalities in amphibians and the abundance of trematode parasite infection, pH, concentrations of 61 pesticides, and levels of orthophosphate and total nitrate. We recorded severe malformations at frequencies ranging from 1% to 90% in nine amphibian species from 53 aquatic systems. Infection of larvae by the trematode Ribeiroia ondatrae was associated with, and functionally related to, higher frequencies of amphibian limb malformations than found in uninfected populations (≤5%). Parasites were concentrated around the basal tissue of hind limbs in infected anurans, and malformations associated with infection included skin webbings, supernumerary limbs and digits, and missing or malformed hind limbs. In the absence of Ribeiroia, amphibian populations exhibited low (0-5%) frequencies of abnormalities involving missing digits or distal portions of a hind limb. Species were affected differentially by the parasite, and Ambystoma macrodactylum, Hyla regilla, Rand aurora, R. luteiventris, and Taricha torosa typically exhibited the highest frequencies of abnormalities. None of the water-quality variables measured was associated with malformed amphibians, but aquatic snail hosts (Planorbella spp.) were significant predictors of the presence and abundance of Ribeiroia infection. Morphological comparisons of adult specimens of Ribeiroia collected from different sites and raised in experimental definitive hosts suggested that all samples represented the same species - R. ondatrae. These field results, coupled with experimental research on the effects of Ribeiroia on amphibians, demonstrate that Ribeiroia infection is an important and widespread cause of amphibian limb malformations in the western United States. The relevance of trematode infection to declines of amphibian populations and the influence of habitat modification on the pathology and life cycle of Ribeiroia are emphasized as areas requiring further research.
History
Journal
Ecological monographsVolume
72Issue
2Pagination
151 - 168Publisher
Ecological Society of AmericaLocation
Tempe, Ariz.ISSN
0012-9615Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2002, Ecological Society of AmericaUsage metrics
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Keywords
abnormality frequency in amphibiansAmbystomaamphibianBufoHylalimb deformityamphibiansparasite-induced malformationsPlanorbella snails vs. Ribeiroia infectionRanaRibeiroia ondatraeTarichatrematodeScience & TechnologyLife Sciences & BiomedicineEcologyEnvironmental Sciences & EcologyLIMB MALFORMATIONSALTERED BEHAVIORXENOPUS-LAEVISFROGSWATERABNORMALITIESMINNESOTAMORTALITYPREDATIONTREMATODAEcology
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