Using Water Level Management to Reduce Harmful Algae Bloom Toxicity Active
Cyanotoxin concentrations that exceed World Health Organization’s drinking water guidance were observed in ~50% of samples taken during bloom events at Lake Kabetogama in Voyagers National Park. Lake Kabetogama is part of a large lake complex that includes other connected lakes, outflows of which are regulated by man-made dams. Here, we are exploring whether dam management could influence the likelihood and toxicity of future blooms.
Cyanobacteria: Harmful Algae Blooms
Due to the dam, water levels can fluctuate over time and have a substantial impact on different ecosystem properties such as nutrient retention rates in sediments and decreases in oxygen supply. If the cyanobacterial impacts to Lake Kabetogama are influenced by the water fluctuation, resource managers could be able to alter management practices to minimize cyanobacterial impacts to the lake.
Scientists aim to estimate the flux of nitrogen and phosphorous into and from sediments at different depths and air exposure periods, and to estimate if these nutrient inputs from sediments are likely to influence cyanobacteria, cyanotoxin, and phytoplankton production.
To accomplish this, scientists collect and incubate sediment cores that were collected in a line perpendicular from shore at differing depths to determine if the fluctuations in the water level influence the nutrient retention rates.
Additionally, water samples were collected during an active algae bloom and brought back to the lab where nutrient spikes were added, and samples were placed in an incubator. At select timepoints samples were taken and filtered to later be analyzed to determine the density of cyanobacteria, chlorophyll-a and cyanotoxin concentrations, and activation of cyanotoxin genes.
Finally, at the site of the active algae bloom, a combination of light and dark bottles with different nutrient spikes were suspended in the water column for a period of time to determine primary production during an algae bloom.
This project is ongoing and is in collaboration with the USGS Upper Midwest Water Science Center, USGS Ohio-Kentucky-Indiana Water Science Center, National Parks Service, and University of Georgia
Referenced Literature
Christensen, V. G., Maki, R. P., & Kiesling, R. L. (2013). Evaluation of internal loading and water level changes: implications for phosphorus, algae production, and nuisance blooms in Kabetogama Lake, Voyageurs National Park, Minnesota. Lake and Reservoir Management, 29(3), 202-215, DOI: 10.1080/10402381.2013.831148
Cyanotoxin concentrations that exceed World Health Organization’s drinking water guidance were observed in ~50% of samples taken during bloom events at Lake Kabetogama in Voyagers National Park. Lake Kabetogama is part of a large lake complex that includes other connected lakes, outflows of which are regulated by man-made dams. Here, we are exploring whether dam management could influence the likelihood and toxicity of future blooms.
Cyanobacteria: Harmful Algae Blooms
Due to the dam, water levels can fluctuate over time and have a substantial impact on different ecosystem properties such as nutrient retention rates in sediments and decreases in oxygen supply. If the cyanobacterial impacts to Lake Kabetogama are influenced by the water fluctuation, resource managers could be able to alter management practices to minimize cyanobacterial impacts to the lake.
Scientists aim to estimate the flux of nitrogen and phosphorous into and from sediments at different depths and air exposure periods, and to estimate if these nutrient inputs from sediments are likely to influence cyanobacteria, cyanotoxin, and phytoplankton production.
To accomplish this, scientists collect and incubate sediment cores that were collected in a line perpendicular from shore at differing depths to determine if the fluctuations in the water level influence the nutrient retention rates.
Additionally, water samples were collected during an active algae bloom and brought back to the lab where nutrient spikes were added, and samples were placed in an incubator. At select timepoints samples were taken and filtered to later be analyzed to determine the density of cyanobacteria, chlorophyll-a and cyanotoxin concentrations, and activation of cyanotoxin genes.
Finally, at the site of the active algae bloom, a combination of light and dark bottles with different nutrient spikes were suspended in the water column for a period of time to determine primary production during an algae bloom.
This project is ongoing and is in collaboration with the USGS Upper Midwest Water Science Center, USGS Ohio-Kentucky-Indiana Water Science Center, National Parks Service, and University of Georgia
Referenced Literature
Christensen, V. G., Maki, R. P., & Kiesling, R. L. (2013). Evaluation of internal loading and water level changes: implications for phosphorus, algae production, and nuisance blooms in Kabetogama Lake, Voyageurs National Park, Minnesota. Lake and Reservoir Management, 29(3), 202-215, DOI: 10.1080/10402381.2013.831148