State Water Resources Research Institute Program

Project ID: 2008ID129B
Title: Investigating Mechanisms by Which Long Distance Circulation (LDC) Enhances Surface Water Quality
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2010
Congressional District: First
Focus Categories: Toxic Substances, Surface Water, Water Quality
Keywords: Harmful Algal Blooms, Water Quality, Long Distance Circulation, Enclosure Experiments
Principal Investigator: Wilhelm, Frank
Federal Funds: $ 20,032
Non-Federal Matching Funds: $ 40,064
Abstract: Surface water is an important resource in Idaho with multiple uses including drinking water and irrigation supply, generation of electricity, habitat for aquatic biota including fish, and various recreational opportunities. Many of these uses can be impaired by blooms of cyanobacteria, small algae, which form surface sums and produce toxins. Harmful algal blooms (HABs) have resulted in the death of livestock, pets, wildlife and even humans; and caused authorities to close entire lakes, resulting in economic loss and reduced property values. The prevention and remediation of HABs is a high priority among lake and drinking water managers.

Although chemicals can be used to control algae in lakes, these typically are expensive, can not treat whole lakes, are relatively short-lived and may have undesirable side effects on the lake environment or may restrict certain uses. Long distance circulation (LDC), the vertical and horizontal transport of water, has also been used to control HABs. It is compatible with all water uses, introduces no chemicals, and can be solar powered, nearly eliminating operating costs and allowing installation in remote areas. However, the widespread adoption of LDC as a management strategy for HABs is currently hindered because its mechanism of action is unknown and thus can not be adequately explained to a skeptic public and professionals.

The proposed research aims to use an experimental approach to examine mechanisms by which LDC controls and prevents HABs. Specifically, the following two hypotheses will be addressed: LDC supplies sufficient nutrients to maintain edible phytoplankton that promote a high abundance of large zooplankton, which effectively graze cyanobacteria to prevent blooms; and LDC disrupts cyanobacteria from their optimal habitat at the lake surface and thus prevents blooms. Experiments will be undertaken in replicated (triplicate) 1 acre U-shaped enclosures with and without long distance circulators representing treatment and control, respectively. Use of large enclosures will allow realistic lake conditions and natural community dynamics to occur within a defined area that can be related to the treatment effect. Enclosures will be sampled regularly (biweekly in spring and fall, and weekly in summer) for chemical (Nitrogen, phosphorus, oxygen etc.), physical (temperature, light penetration, etc.) and biological (phytoplankton and zooplankton abundance, spatial distribution and diversity) parameters. A comparative statistical approach will be used to analyze treatment effects relative to the controls. It is expected that this experimental design will allow a rigorous scientific approach to test specific hypotheses by which LDC controls HABs. In the long-term, the enclosure set up will also lend itself as an ideal framework with which to address additional emerging water quality issues using an experimental hypothesis-driven approach. The research program will involve graduate and undergraduate students and results will be presented in published manuscripts and presentations at national and international conferences. Specific emphasis will be placed on communicating the results to the public and lake professionals.

Progress/Completion Report, 2008, PDF
Progress/Completion Report, 2009, PDF

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