Local and systemic controls on fish and fish habitat in South Dakota rivers and streams: Implications for management.

摘要

Assessments of the health of rivers and streams in prairie environments would improve if the role of systemic patterns and processes among geologic-climatic settings in controlling physical habitat and fish communities were better defined. My research approach was based on a premise that assessments of the health of rivers and streams in prairie environments would benefit from studies that (1) examine the moderating effects of systemic patterns and processes by comparing physical habitat continua and fish communities among geologic-climatic settings, (2) determine the relative influence of locally interacting variables (e.g., channel shape and riparian vegetation) and systemic processes in structuring physical habitat and fish communities among a range of streams sizes, and (3) test the effects of biotic and abiotic controls on habitat partitioning by fish during critical periods of low flows common in prairie streams.; In the first study, longitudinal trends in channel morphometry, bankfull dimensions, stream bank and riparian traits, substrate, and fish community attributes were compared between the Bad River in a semi-arid region of western South Dakota and the Big Sioux River in the sub-humid region in eastern South Dakota. My findings show that while prairie streams in sub-humid regions exhibit a truncation of the river continuum concept (RCC), physically and biologically, in semiarid regions, further truncation of the upper part of the RCC occurs. While both rivers had similarities in pioneering species in the upper parts of each river, only the Big Sioux River had a headwater component in the upper part.; In the second study, findings indicate that variation in channel morphometry, physical habitat, and riparian-related habitat decreases with watershed size in a subhumid prairie stream. Variation in channel morphometry, physical habitat, and riparian related habitat in tributaries could not be explained by local riparian conditions or adjacent land use.; In the laboratory study, low flow conditions were simulated in three experimental streams. My findings suggest that predation is more important than competition in partitioning habitat use by minnow species, and that woody debris may play a critical role as fish habitat during droughts. (Abstract shortened by UMI.)