Potamoplankton of the Maumee River during 2018 and 2019: The relationship between cyanobacterial toxins and environmental factors |
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| Affiliation: | 1. F.T Stone Laboratory, The Ohio State University, 878 Bayview Ave., Put-in-Bay, OH 43456, USA;2. Biological Sciences, Bowling Green State University, Bowling Green, OH, USA;3. Department of Biology and Environmental Science and National Center for Water Quality Research, Heidelberg University, Tiffin, OH, USA;1. Cooperative Institute for Great Lakes Research, School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA;2. University of Minnesota Duluth, Duluth, MN 55812, USA;3. Fedwriters at National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48108, USA;1. University of Windsor, Great Lakes Institute for Environmental Research, Windsor, Ontario, Canada;2. McMaster University, W. Booth School of Engineering Practice and Technology, Hamilton, Ontario, Canada;1. Program of Geography, College of Liberal Arts, University of Minnesota, Duluth, MN 55812, USA;2. Department of Biology, Clarkson University, Potsdam, New York, NY 13699, USA;3. Natural Resources Research Institute, University of Minnesota Duluth, 5013 Miller Trunk Highway, Duluth, MN, USA;4. Annis Water Resources Institute, Grand Valley State University, 740 West Shoreline Drive, Muskegon, MI 49441, USA;5. Great Lakes Research Center, Michigan Technological University, Houghton, MI 49931, USA;1. Department of Microbiology, University of Tennessee, Knoxville, TN, United States;2. Water Quality Engineering, Technical University of Berlin, Berlin, Germany;3. Department of Earth & Environmental Science, University of Michigan, Ann Arbor, MI, United States;4. Cooperative Institute for Great Lakes Research, University of Michigan, Ann Arbor, MI, United States;1. Technische Universität Darmstadt, Institute of Applied Geosciences, Schnittspahnstr. 9, 64287 Darmstadt, Germany;2. Polytechnique Montréal – Department of Civil, Geological and Mining Engineering, Montreal, Canada;3. Sharif University of Technology, Urmia Lake Restoration Program, Department of Civil Engineering, Azadi Ave, P.O. Box: 11155, 9313 Tehran, Iran |
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| Abstract: | While algal blooms are common in eutrophic lakes, blooms can also occur in tributaries that load nutrients into the lake. We sampled six sites along a 122-km stretch of the Maumee River May through October 2018 and 2019 at weekly to biweekly intervals to determine if algal blooms occur, in particular toxic cyanobacteria, and to provide insights on potential environmental drivers of blooms. Samples were analyzed for concentrations of potamoplankton (=riverine phytoplankton), chlorophyll a, nutrients, cyanobacterial toxins, microcystins and saxitoxins, and cyanotoxin genes (mcyE and sxtA). Extreme precipitation in 2019 resulted in more high discharge events during 2019 than in 2018. Chlorophyll a ranged from 50 µg/L to 300 µg/L during periods of low discharge (<50 m3/s), and green algae and diatoms accounted for the majority of the chlorophyll a. In both years, cyanobacteria comprised a low proportion of all chlorophyll a, usually<20 %, but microcystins and saxitoxins were detectable in 38.7 % and 16.7 % samples, respectively, and mcyE and sxtA were detected in 36.2 % and 59.7 % samples, respectively. Therefore, cyanotoxins were present even when cyanobacteria were not at bloom densities. Chlorophyll a, cyanotoxin genes, and microcystins negatively correlated with discharge rate measured on the date of sample collection. Together our results suggest that cyanotoxins can occur in any portion of the Maumee River during low discharge conditions. Climate change is expected to reduce precipitation during the warm summer months in the Maumee River watershed and thus possibly increase the frequency of low discharge conditions that favor cyanobacteria. |
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| Keywords: | Microcystins Saxitoxins Harmful algal blooms Climate change |
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