Bioindicators Enhance Stream Assessment: Physicochemical Parameters’ Effect on Salamander Abundance

Ecological restoration has emerged as a critical tool for addressing ecosystem degradation worldwide. The Stream Quantification Tool (SQT) represents a significant advancement in stream restoration methodology, providing a standardized framework for quantifying stream functions and evaluating project outcomes. We investigated relationships between salamander abundance and physicochemical parameters from the SQT (nitrogen, turbidity, temperature, and composite SQT physicochemical score) across 16 streams in the upstate region of South Carolina. Stream salamanders can be reliable bioindicators due to their philopatric nature, longevity, and stable populations, making them valuable for assessing stream restoration effectiveness. Six salamander species (n = 394 individuals) were identified across 14 streams where salamanders were present. N-mixture models were used to analyze abundance patterns while accounting for imperfect detection. Turbidity was the strongest negative predictor of salamander abundance, followed by nitrogen. Removal of an agriculturally impacted stream with elevated turbidity substantially altered model rankings, making the null model top-ranked, followed by nitrogen, composite physicochemical score, and temperature. These findings demonstrate turbidity’s critical role in salamander abundance. Management practices should prioritize erosion and sediment control solutions for salamander conservation. For SQT biological monitoring, we recommend focusing on turbidity and nitrogen as key parameters affecting salamander abundance in stream assessments.