Changes To Water Chemistry And Implications For Sensitive Aquatic Biota In Southern Blue Ridge Streams

Freshwater systems, which constitute a mere 2.5% of Earth's total water, are increasingly impacted by abiotic and biotic factors. Changes to land use and other anthropogenic stressors are widely understood to drive the alteration of freshwater ecosystems. The Southern Blue Ridge is among North America's most biologically diverse regions and is home to the forested headwaters of the Tennessee and Ohio drainages. I examined long-term (~60 years) water quality and land use (18 years) datasets to assess which broad-scale changes in water chemistry may be correlated with recent declines of aquatic species in this region. My in-depth analysis of water chemistry from 80 Hydrologic Unit Code (HUC10) watersheds revealed increases in DO concentration, TDS, pH and spC over the last 5 decades. I used descriptive statistics, Spearman rank correlations, and model fitting to understand how water chemistry has changed over time and in relation to urbanization in a primarily forested region. Species modeling suggests freshwater fish are the taxa that have experienced statistically significant changes in watershed occupancy from 1900-2010.