Stream assessment and fish management through an ecogeomorphological lens

Stream physical characteristics and fish communities are largely thought to be governed by a complex interplay between local- and landscape-level factors along the longitudinal continuum of the drainage network.  However, sampling methodologies related to stream condition and fish communities are largely conducted at the reach-scale, underscoring the need for monitoring approaches that link fish-environmental relationships in mechanistic ways.  Relationships between a stream’s geomorphic template and fish communities may offer a unique, linked structural-functional perspective.  Drawing on field investigations from Vermont, Idaho, and Ohio, we illustrate how stream geomorphology and fish assemblage diversity and productivity are tightly linked, even across geographic regions.  Our results also suggest that functional patterns of fish communities, including trophic structure and energy flows (C and N), are also strongly associated with geomorphic characteristics.  Overall, our results point to structural-functional patterns of fish assemblages that are uniquely associated with stream morphology and are distributed in a patchy, although somewhat predictable fashion.  Given the strength of these findings, it is likely that further integration of ecogeomorphological approaches into stream assessment and biomonitoring protocols may be an effective complement to current stream conservation and fish management efforts.