Differential effects of exotic Eurasian wild pigs and native peccaries on physical integrity of streams in the Brazilian Atlantic Forest

摘要

Wild boars (Sus scrofa Linnaeus, 1758), native to Eurasia and Africa, are one ofthe world’s most widely distributed invasive species. Their impacts on terrestrialenvironments have been well documented, however little is known about theireffects on aquatic environments. We used standardized physical habitat surveys tocompare the use of streams by invasive wild pig and native white-lipped peccaries(Tayassu pecari Link, 1795), and their effects on the physical structure from fourfirst-order streams in the Brazilian Atlantic Forest. Two of these streams were usedsolely by wild pigs, while two were solely used by peccaries. Each stream wassubdivided by cross-sectional transects into continuous sections, each 10-m inlength, where we measured the intensity of use by each species and differentvariables related to the stream physical habitat. Although both species used thestreams, wild pigs altered physical and environmental parameters more, and withgreater intensity, than the native peccaries. Wild pigs decreased the stream bankangle and the riparian ground cover, leading to local erosion, increased finesedimentation and wetted width, and declined stream depth. We recommend studiesto evaluate the biological consequences of the alterations caused by introduced wildpigs, which should be conducted along with plans of population control inenvironments where the wild pig is considered an invasive species.