INFLUENCES OF AGRICULTURAL LAND USE ON CLINOSTOMUM ATTENUATUM METACERCARIAE PREVALENCE IN SOUTHERN GREAT PLAINS AMPHIBIANS, USA

Agricultural land use surrounding wetlands can influence various aspects of amphibian ecology. Amphibians in the Southern Great Plains of North America exhibit altered demographics and body size in playa wetlands with cultivated watersheds compared to those in grassland watersheds. We identified metacercariae of the trematode Clinostomum attenuatum in dominant playa amphibians and therefore examined its prevalence between postmetamorphic individuals inhabiting wetlands in grassland and cultivated landscapes. During 1999 and 2000, 5,621 Bufo cognatus, 9,565 Ambystoma tigrinum mavortium, and 49,373 Spea multiplicata captured at playa wetlands were examined for C. attenuatum metacercariae. In general, metacercariae prevalence in amphibians was 2-11 times greater in grassland than in cropland wetlands. Metacercariae prevalence also was 2-13 times greater in 1999 than 2000. Land-use differences may be related to shortened hydroperiods in disturbed cropland wetlands, which may interrupt the life cycle of C. attenuatum. Yearly differences also may be related to hydroperiod; annual rainfall was two times greater in 1999 than 2000. Our results suggest that agricultural land use may influence metacercariae prevalence in amphibians on the Southern Great Plains, possibly through indirect effects on wetland hydroperiod.