The effects of cattle derived nutrients on growth rates of Arizona Tiger Salamander hatchlings in pastureland

Abstract

Nitrogen is a critical element in biological systems, with its cycling increasingly influenced by human activities, particularly in agriculture. In Colorado, where 50% of land is used for agriculture, cattle grazing may impact the ecosystems of montane and subalpine ponds inhabited by Ambystoma mavortium nebulosum. My study examined how cattle presence affects ammonium, phosphorus, and hatchling growth rates in these ponds. I collected and measured hatchlings from ten ponds, and qualitatively assessed cattle presence. Water samples were analyzed for ammonium and phosphorus concentrations. Results showed that low to medium cattle presence significantly increased hatchling growth rates but there was no significant correlation with ammonium or phosphorus concentrations. However, phosphorus was significantly correlated with reduced growth rates in a linear model, though I have uncertainty about this trend due to slight inconsistencies in data analysis. Additional trends suggested potential correlations between cattle presence and other water quality variables, such as dissolved oxygen and pH, though these were not statistically significant. The study highlights the need for further research with larger sample sizes and more comprehensive water quality measurements to better understand the impacts of cattle on high-elevation pond ecosystems and salamander populations.