Assessing the vulnerability of stream communities and the consistency and use of biotic indices in least-disturbed streams

The need in freshwater conservation is to understand the current status of aquatic biota so that we can recognize when degradation or changes occur. Because stream habitats and communities are dynamic, it is important to understand the natural variability through time and space so that departures may be used to make inferences on stability or instability. Additionally, attempting to predict aquatic communities that are more likely to experience a change in diversity, abundance, and function from anthropogenic impacts may help to prioritize locations for management action. Finally, assessing the consistency of various biotic indices (quantitative tools used to convey lotic ecosystem health) will aid in conveying a more holistic depiction of stream condition and to prioritize locations and biota for management action. To address each of the aforementioned data gaps, we used fish and aquatic invertebrate community data collected from 1988 to 2013 from 88 sites within seven National Park Service (NPS) units represented within the Heartland Inventory and Monitoring Network. The fish community (Index of Biotic Integrity) at each of the seven NPS units was less temporally variable than spatially variable. This relationship was not found with aquatic invertebrate community (Hilsenhoff Biotic Index) in that only three of the seven NPS units were less temporally variable than spatially variable