The wild pig (Sus scrofa) is one of the most destructive invasive species in the United States and causes an estimated $1.5 billion of damage annually. While the physical damage is obvious, their impacts on local watersheds are relatively unknown. Understanding this relationship may improve management strategies and predict changes in ecosystems, especially as wild pigs are rapidly expanding their range. Our first hypothesis is that pig rooting in riparian zones increases sediment and other pollutants in surface waters due to erosion and sediment transport, affecting bank stability and water quality. Our second hypothesis is that pig disturbance of soil and detritus changes soil characteristics and impacts microbial activity, including nitrogen mineralization (NMIN), nitrification, and microbial biomass. We are examining water quality (physiochemical and microbial characteristics) and soil nitrogen responses in watersheds on three privately-owned tracts in southeast Alabama. Water samples are being collected to measure concentrations and loads of sediment (TSS), nitrate and ammonium, base cations and chloride (Ca, Mg, Cl), and E. coli and other fecal coliforms. Soil samples are being analyzed for NMIN, nitrification rates, and microbial biomass. These data will be used to detect changes in nitrogen budgets in relation to the degree of pig disturbance.
Results/Conclusions
Preliminary results indicate that water quality is being impacted in watersheds with the greatest amount of pig disturbance. Analyses show that E. coli MPN is higher by a ratio of 5:1, although DNA analyses are inconclusive at this time. Nitrate concentrations and TSS are higher in the disturbed areas as well (e.g. in the case of nitrate by a ratio of 3:1). Analysis of soil samples indicate higher NMIN and microbial C and N in heavily disturbed areas which suggests that the elevated NMIN could provide an additional source of nitrogen to streams. This information is further evidence that pig eradication and control initiatives should be high priority for land owners and land managers to protect economic resources, wetland services, and even human health. While pig eradication is difficult and costly, management on private lands is necessary to halt the spread of pigs and their negative impacts on the landscape. Our research fills a gap of knowledge on the influence of pig damage in riparian systems and uncovers essential information that can influence management of this invasive species to safeguard water quality in local watersheds.