Fish Response to Velocity-Related Flow Modifications in a Warm-Water Stream

Stream Restoration;Velocity;Warm Water Streams;Natural Resources and Environment

Mikus, AmyWebb, Paul ;

University of Michigan

关键词: Stream Restoration;    Velocity;    Warm Water Streams;    Natural Resources and Environment;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/69251/Amy%20R.%20Mikus%20MS%20Thesis.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Recent developments in the field of stream restoration have led to multiple strategiesfor improving and restoring a variety of fish habitats across spatial and geographical scales.These habitat modifications often aim to increase overall fish abundance or species diversitythrough the installation of in‐stream structures. Historically these structures were common incold water streams for improvement of salmonid habitats, but as stream restoration projectsare needed in smaller and warm water streams it is important to understand and quantify theeffects of in‐stream structures on other fishes. Velocity is thought to be an importantparameter in determining fish habitat choices and hence essential for successful restoration ofaquatic ecosystems. This project attempted to change velocity profiles using in‐streamstructures and determine if these changes attracted fishes. In this project solid blocks wereinstalled perpendicular to the primary flow direction at ten sites located in runs and riffles in awarm water stream in Northern Michigan in order to create velocities similar to thoseexperienced by fishes in pool habitats. The modified sites and two pools were surveyed bysnorkeling over a one‐month period to determine fish use of the newly created habitats. Thephysical flow conditions were measured using an Acoustic Doppler Velocimeter and a Marsh‐McBirney flow meter.Fishes did not utilize the artificially created habitats despite large reductions of localvelocity behind the blocks. Current speeds behind the blocks were actually lower than thosemeasured in pools and in some cases were opposite in direction to the main channel current.Pools and modified sites showed significant differences in mean velocity, velocity fluctuations,turbulent kinetic energy, and turbulence intensity. Velocity gradients which developed at theedges of the blocks may have been a barrier to fish access to the modified sites, since they weremuch larger than those occurring in natural pools. Results suggest that several physicalcharacteristics of flow patterns are crucial in describing the complexity of fish habitats and thatvelocity alone does not provide enough information to determine the suitability of an area forfishes.