Portland State University. Environmental Sciences and Resources Ph. D. Program
Date of Award
Doctor of Philosophy (Ph.D.) in Environmental Sciences and Resources
Environmental Sciences and Resources
1 online resource (viii, 161 pages)
Cyanobacterial blooms -- Oregon -- Upper Klamath Lake, Aphanizomenon, Water quality
The ability to regulate buoyancy (sinking and floating) using cellular gas vesicles is a unique characteristic that allows many common bloom-forming cyanobacteria to accumulate at water surfaces and dominate systems. Typical control and management strategies include nutrient manipulation and phosphorus reduction, which are effective but do not reduce the advantage of buoyancy control. Since buoyancy control is based upon a mechanism that is driven by photosynthesis along with environmental conditions that trigger vesicle formation and ion exchange, buoyancy regulation can be influenced by manipulating extracellular conditions. In this study I manipulated extracellular conditions using wetland water and additions of potassium, sodium, and calcium in small-scale lab experiments and larger scale, near-lake containers with Aphanizomenon flos-aquae from Upper Klamath Lake, Oregon. The results indicate a target mixture of 10% wetland water reduces surface accumulation, increases cellular turgor pressure (a measure of the ability of gas vesicle forming cells to control buoyancy), and leads to fewer rafts at the surface of the water column. By adding ions at the same concentration as the target wetland mixture, similar results were found. This research represents the basis of a possible strategy for mitigating surface blooms of buoyant cyanobacteria in lakes using wetland water and/or ion additions that could be used in tandem with nutrient manipulation and phosphorus reduction.
Rouhe, Arick Christopher, "Using Wetlands to Prevent the Surface Accumulation of Aphanizomenon flos-aquae from Upper Klamath Lake" (2018). Dissertations and Theses. Paper 4514.