Microcystins (MC) are a class of cyanotoxins produced by many cyanobacteria taxa. Although toxic to metazoans, the evolution of microcystin pre-dates the appearance of metazoans, and so MC did not originate as a toxin to potential metazoan grazers. One hypothesized functional role of microcystin is the management and acquisition of metals, several of which form complexes with MC intracellularly. Metals are often used to build enzymes within the cell that allow cyanobacteria to use non-preferred nitrogen (N) and phosphorus (P) sources, such as nitrate, urea and organic P. If trace metals are in low supply, primary producers may become limited because of their inability to access these non-preferred N and P forms. Furthermore, if MC are used for metal acquisition and management, we would expect that as demand for these trace metals varies, so will the production of MC. We performed 7 mesocosm experiments in triplicate on naturally occurring phytoplankton communities from two nearshore habitats that experience annual cyanobacterial blooms (Green Bay, Lake Michigan and Maumee Bay, Lake Erie). In these experiments, we provided natural communities with amendments of labile nutrients (NH4+ and/or PO43-) and trace metals (Fe, Zn, Ni and Mo) and measured growth (as chlorophyll a), the relative abundance of MC-producing genes (mcyE gene copies), the relative abundance of MC-producing RNA and the MC concentration. Experiments were performed by James H Larson and Sean W Bailey at the Upper Midwest Environmental Sciences Center (UMESC). Genetic measurements were performed by Erin A. Stelzer (Ohio-Indiana-Kentucky Water Science Center) on samples collected at UMESC. Cyanotoxin measurements were performed by Keith A. Loftin (Kansas Water Science) on samples collected at UMESC.

To address how phytoplankton in the Great Lakes respond to macro- and micronutrients, we conducted a bottle incubation enrichment experiment using water collected from blooming (Maumee Bay and Fox River) and non-blooming sites (Detroit River and Ford River) in Lakes Erie and Michigan, respectively, during late summer. Surface water from these locations was collected and taken to Kent State University either via overnight shipping (Lake Michigan sites) or driven directly after collection (Lake Erie sites). Chlorophyll a (an index of overall biomass), community composition and toxicity were all measured as responses to treatments of labile inorganic nitrogen (N), phosphorus (P) and a mixture of micronutrients (chemical symbols: Fe, Mn, Mo, Ni, Zn).

In 2015-2018, the U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency Great Lakes Restoration Initiative investigated the biodegradation of microcystins in source waters and sand filters from drinking-water plants in the Western Lake Erie Basin. Four source waters and three sand filtrate samples were collected from the intakes and sand filters of Lake Erie drinking-water plants and transported to the USGS Ohio Water Microbiology Laboratory, where investigators set up microcosms to enrich for and identify indigenous bacteria capable of degrading microcystins. Quality control samples were set up in the microcosms to check analyses and included positive controls, negative controls, and replicates. Microcystin biodegradation was quantified by the disappearance of the toxin as compared to control cultures in microcosm and microplate experiments, and by the presence of a gene within microcystin-degrading bacteria that encodes for an enzyme involved in the initial steps of biodegradation. Bacteria were isolated from microcosms enriched with microcystin-LR (MC-LR) and MC-LR concentrations were measured over time by ELISA (table 1). Isolates were selected from the microcosm experiments for further growth testing in microplate experiments with various enrichment media and MC-LR over 96 hours (table 2). Biofilm formation potential for the isolates were also measured and data is shown in table 3. Isolate absorbances of ten potential microcystin degraders were incubated in a microplate with MC-LR as the sole carbon source (table 4) and concentrations of MC-LR in microplate wells were measured over time (table 5).

In 2015-2018, the U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency Great Lakes Restoration Initiative investigated the biodegradation of microcystins in source waters and sand filters from drinking-water plants in the Western Lake Erie Basin. Four source waters and three sand filtrate samples were collected from the intakes and sand filters of Lake Erie drinking-water plants and transported to the USGS Ohio Water Microbiology Laboratory, where investigators set up microcosms to enrich for and identify indigenous bacteria capable of degrading microcystins. Quality control samples were set up in the microcosms to check analyses and included positive controls, negative controls, and replicates. Microcystin biodegradation was quantified by the disappearance of the toxin as compared to control cultures in microcosm and microplate experiments, and by the presence of a gene within microcystin-degrading bacteria that encodes for an enzyme involved in the initial steps of biodegradation. Bacteria were isolated from microcosms enriched with microcystin-LR (MC-LR) and MC-LR concentrations were measured over time by ELISA (table 1). Isolates were selected from the microcosm experiments for further growth testing in microplate experiments with various enrichment media and MC-LR over 96 hours (table 2). Biofilm formation potential for the isolates were also measured and data is shown in table 3. Isolate absorbances of ten potential microcystin degraders were incubated in a microplate with MC-LR as the sole carbon source (table 4) and concentrations of MC-LR in microplate wells were measured over time (table 5).

The data contained in the worksheet provides the quantity data of Cyanobacterial 16S sequences, qPCR and water quality parameters. This dataset is associated with the following publication: Li, H., T. Miller, J. Lu, and R. Goel. Nitrogen fixation contribution to nitrogen cycling during cyanobacterial blooms in Utah Lake. CHEMOSPHERE. Elsevier Science Ltd, New York, NY, USA, 302: 134784, (2022).

Lake Superior is historically a nutrient poor lake that does not typically support significant cyanobacterial blooms. However, the lake has been experiencing an increase in blooms in the western portion of the basin recently. The largest blooms documented have occurred after recent major flooding events, indicating that nutrients transported to the lake during these events may be a source for the blooms. This study looks into the combination of streambed sediment-derived nutrient data during base flow conditions and suspended and settled sediment-derived nutrient data from storm events to provide information about nutrient transformation and storage in the river networks of the Bois Brule River and Siskiwit River watersheds, both tributaries of western Lake Superior.

Lake Superior is historically a nutrient poor lake that does not typically support significant cyanobacterial blooms. However, the lake has been experiencing an increase in blooms in the western portion of the basin recently. The largest blooms documented have occurred after recent major flooding events, indicating that nutrients transported to the lake during these events may be a source for the blooms. This study looks into the combination of streambed sediment-derived nutrient data during base flow conditions and suspended and settled sediment-derived nutrient data from storm events to provide information about nutrient transformation and storage in the river networks of the Bois Brule River and Siskiwit River watersheds, both tributaries of western Lake Superior.

This dataset records Cladophora and associated benthic algae, collectively Cladophora community or submerged aquatic vegetation (SAV), biomass collected during the growing season of 2022 at stations located along the U.S. shoreline of Lakes Michigan, Huron, Erie, and Ontario. It also records a variety of supporting data collected at Cladophora measurement stations. These supporting data include: - seasonal time series of light, currents, wave action, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen from moored sensors at a subset of stations; - measurements of Secchi disk depth and water chemistry; - water column profiles of PAR, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen; - diver observations of SAV, dreissenid mussels, round goby abundance, and substrate properties; - measurements of dreissenid mussel abundance and size class distribution coincident with SAV biomass; - nutrient content of SAV, dreissenid mussels, and sediments; - and information about sampling locations and operations. Similar data were collected at several of the same transects within four Great Lakes in 2018, 2019, 2020, and 2021 are available at (2018) https://doi.org/10.5066/P9E570JS, (2019) https://doi.org/10.5066/P99O4QXB, (2020) https://doi.org/10.5066/P9O9FSTT, and (2021) https://doi.org/10.5066/P9449EUF.

This dataset records Cladophora and associated benthic algae, collectively Cladophora community or submerged aquatic vegetation (SAV), biomass collected during the growing season of 2021 at stations located along the U.S. shoreline of Lakes Michigan, Huron, Erie, and Ontario. It also records a variety of supporting data collected at Cladophora measurement stations. These supporting data include: - seasonal time series of light, currents, wave action, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen from moored sensors at a subset of stations; - measurements of Secchi disk depth and water chemistry; - water column profiles of PAR, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen; - diver observations of SAV, dreissenid mussels, round goby abundance, and substrate properties; - measurements of dreissenid mussel abundance and size class distribution coincident with SAV biomass; - nutrient content of SAV, dreissenid mussels, and sediments; - and information about sampling locations and operations. Similar data were collected at several of the same transects within four Great Lakes in 2018, 2019, and 2020 are available at (2018) https://doi.org/10.5066/P9E570JS, (2019) https://doi.org/10.5066/P99O4QXB, and (2020) https://doi.org/10.5066/P9O9FSTT.

This dataset records Cladophora and associated benthic algae, collectively Cladophora community or submerged aquatic vegetation (SAV), biomass collected during the growing season of 2021 at stations located along the U.S. shoreline of Lakes Michigan, Huron, Erie, and Ontario. It also records a variety of supporting data collected at Cladophora measurement stations. These supporting data include: - seasonal time series of light, currents, wave action, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen from moored sensors at a subset of stations; - measurements of Secchi disk depth and water chemistry; - water column profiles of PAR, temperature, specific conductivity, turbidity, pH, phycocyanin, chlorophyll, and dissolved oxygen; - diver observations of SAV, dreissenid mussels, round goby abundance, and substrate properties; - measurements of dreissenid mussel abundance and size class distribution coincident with SAV biomass; - nutrient content of SAV, dreissenid mussels, and sediments; - and information about sampling locations and operations. Similar data were collected at several of the same transects within four Great Lakes in 2018, 2019, and 2020 are available at (2018) https://doi.org/10.5066/P9E570JS, (2019) https://doi.org/10.5066/P99O4QXB, and (2020) https://doi.org/10.5066/P9O9FSTT.