Amphibians, Trematodes, and Deformities: An Overview from

ABSTRACT: Deformed amphibians have been reported from several locations in North America, with the prev-alences of these deformities varying from region to region. These deformities have been attributed to both anthropogenic and natural changes in the abiotic and biotic factors in the environment. Suggested causes for these deformities include toxins, ultraviolet B irradiance, larval trematodes, or synergistic interactions of some or all of these factors. Several studies, beginning in 1990, have investigated the helminths infecting amphibians from southern Michigan, U.S.A., with emphasis on locating populations of deformed amphibians. Although high numbers of many species of larval and juvenile helminths (Fibricola sp., Clinostomum sp., gorgoderid, strigeid, or unknown metacercariae, Mesocestoides sp., Spiroxys sp.) were found infecting the hind limbs, these helminths did not cause deformities in southern Michigan. KEY WORDS: helminths, larval trematodes, amphibians, deformities, Michigan. Many types of gross limb abnormalities have been reported from natural populations of am-phibians in North America, and several hypoth-eses have been suggested to explain their occur-rence. Chemical contaminants in the environ