ScholarWorks at University of Montana

The ecology of the filamentous green algae Cladophora glomerata has been studied in the Clark Fork River for many years due to its influence on dissolved oxygen, pH, aquatic organisms, and recreational use. While a number of factors contribute to algal persistence and dominance, the influence of fluid velocity on resource acquisition (i.e., nutrient uptake) and removal by shear stress are important processes affecting Cladophora distribution in space and time. A basic introduction to mechanistic principles governing removal and nutrient uptake is provided, followed by techniques to examine such relationships in rivers. Techniques include use of low-cost unmanned aerial vehicles (UAVs) to remotely sense the spatial location of algae, and the use of acoustic Doppler current profilers (ADCPs) to assess habitat suitability and optimal/critical velocities for algal establishment. In 2013, a river site downstream of Deer Lodge exhibited percent algal cover that ranged from < 5 to > 50%, increasing immediately after vernal freshet, peaking midsummer, and declining in the fall. When paired with velocity observations from over 3,500 ADCP observations, the mean measured velocity profile in algal covered areas averaged 0.67 m s⁻¹, whereas it was found to be 0.41 m s⁻¹ in uncovered locations (p

Uncontrolled disposal of mining wastes in the Butte mining districts resulted in extirpation of fishes from Silver Bow Creek throughout the 20^th century. Superfund remediation has been ongoing in the watershed since 1998 and is near completion. Overall, metal concentrations in Silver Bow Creek are reduced from pre-remediation levels however. However, the stream is influenced by municipal sewage, and during midsummer, hypoxia has been observed at night downstream from the wastewater discharge. Despite the water quality problems, six fish species, including three sensitive salmonids, now inhabit Silver Bow Creek. To evaluate the success of remediation in reestablishing salmonid populations, spatially-continuous fish abundance and habitat surveys were conducted in coordination with synoptic water quality measurements throughout 34 stream km during the summer of 2011. An extensive stream portion (≈6 km) had low dissolved oxygen (DO/L), and minimum DO concentrations were