Application of diatom multi-metric indices to state monitoring data

Description: Diatoms are sensitive to changes in environmental conditions and can be used to evaluate the biotic integrity of streams and rivers. Carlisle et al. (2022) recently developed multi-metric indices (MMIs) for three aggregated level II ecoregions in the conterminous United States. These MMIs improved upon previous efforts to develop diatom-based bioassessment tools by modeling natural variation, removing metrics sensitive to taxonomic inconsistency, and being made publicly available via a web-based application through which independent data can be entered and used to assess biotic integrity. In this webinar, we describe the application of Colorado state diatom counts since 2004 to these MMIs. We walk through each step of using the web-based application with independent state data, including navigating the interface, assigning site identifiers that are consistent with the National Hydrography Dataset, updating diatom taxonomy, and computing MMI scores. Using the national MMIs, we found that 62% of samples across the state of Colorado reflect possible disturbance of diatom biotic integrity. Phosphorus and conductivity were the most dominant stressors related to diatom disturbance in Colorado streams. The present work represents the first application of independent state monitoring data to the national MMIs and provides guidance for how other states and regions can use these bioassessment tools.

Target audience:
Water managers, policymakers, researchers, and others interested in applying regional diatom data to publicly available tools for assessing biotic integrity.