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).

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.

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.

An interdisciplinary and multiagency study was undertaken to study harmful algal bloom (HAB) dynamics on the Caloosahatchee River, which drains to the west from Lake Okeechobee into the Gulf of Mexico. Algae and cyanobacteria play crucial roles in aquatic ecosystems, but under favorable environmental conditions certain taxa may experience population growth booms resulting in HABs. Four independent mesocosm experiments were conducted in September 2019, June 2020, September 2020, and February 2021 to capture natural temporal variability in water quality and phytoplankton assemblages. The experimental installation consisted of three floating metal cradles each containing four fiberglass chambers filled with native river water. The twelve chambers were assigned to one of four treatments: phosphate (P), nitrate (N), ammonium (A), or control (C) – each with 3 replicates. The P, N, and A treatment chambers were enriched by applying a concentrated dosing solution of either dibasic dodecahydrate sodium phosphate, anhydrous sodium nitrate, or liquid ammonium hydroxide respectively to elevate concentrations above ambient levels. The mesocosms were treated and sampled over a 72-hour period (Time 0, Time 24, Time 48, Time 72). This dataset contains phytoplankton absolute and relative abundance measures at the genus level as natural units (NU/mL), cell densities (cells/mL), and biovolumes (um3/mL).

This dataset contains a tabular file of phytoplankton abundance and community composition analysis in samples collected from eight sites in the Western Lake Erie Basin; four sites in Grand Traverse Bay, Lake Michigan; and five sites in Saginaw Bay, Lake Huron. Samples were collected and processed by the Great Lakes Science Center of the U.S. Geological Survey (USGS) and analyzed by BSA Environmental Inc. Lake Erie sample collection spanned years 2014-2018 with some sites sampled throughout this period and other sites sampled in only some years. Sample collection in Grand Traverse Bay, Lake Michigan and Saginaw Bay, Lake Huron occurred in 2015. Sample collection was focused in summer and early fall months and data only represent the community present in these seasons. Site in each basin to represent a gradient of nutrient availability for that basin and are not randomly distributed. The dataset includes phytoplankton taxa (genus and species), division, tally (number of cells counted for each taxa present), density (cells per liter), and total biovolume (cubic micrometers per liter) for each sample collected. These data can be used to assess the community composition of phytoplankton at the sites, identify cyanobacteria species, and determine abundance and biovolume of any known toxin-producing cyanobacteria. The data were part of a larger study and associated water quality and cyanotoxin data are available through the USGS National Water Information System (NWIS) by searching for site numbers.

This dataset contains a tabular file of phytoplankton abundance and community composition analysis in samples collected from eight sites in the Western Lake Erie Basin; four sites in Grand Traverse Bay, Lake Michigan; and five sites in Saginaw Bay, Lake Huron. Samples were collected and processed by the Great Lakes Science Center of the U.S. Geological Survey (USGS) and analyzed by BSA Environmental Inc. Lake Erie sample collection spanned years 2014-2018 with some sites sampled throughout this period and other sites sampled in only some years. Sample collection in Grand Traverse Bay, Lake Michigan and Saginaw Bay, Lake Huron occurred in 2015. Sample collection was focused in summer and early fall months and data only represent the community present in these seasons. Site in each basin to represent a gradient of nutrient availability for that basin and are not randomly distributed. The dataset includes phytoplankton taxa (genus and species), division, tally (number of cells counted for each taxa present), density (cells per liter), and total biovolume (cubic micrometers per liter) for each sample collected. These data can be used to assess the community composition of phytoplankton at the sites, identify cyanobacteria species, and determine abundance and biovolume of any known toxin-producing cyanobacteria. The data were part of a larger study and associated water quality and cyanotoxin data are available through the USGS National Water Information System (NWIS) by searching for site numbers.

This dataset contains a tabular file of phytoplankton abundance and community composition analysis in samples collected from two sites in the Western Lake Erie Basin and one inland lake site in northeast Ohio. Samples were processed by the Ohio Water Microbiology Lab of the U.S. Geological Survey (USGS) and analyzed by BSA Environmental Inc. and during federal fiscal years 2016-2018. The dataset includes phytoplankton taxa (genus and species), division, tally (number of cells counted for each taxa present), density (cells per liter), and total biovolume (cubic micrometers per liter) for each sample collected. These data can be used to assess the community composition of phytoplankton at the sites, identify cyanobacteria species, and determine abundance and biovolume of any known toxin-producing cyanobacteria. The data were part of a larger study, "Predicting microcystin concentration action-level exceedances resulting from cyanobacterial blooms in selected lake sites in Ohio", in which site-specific multiple linear regression models were developed for eight sites in Ohio−six in the Western Lake Erie Basin and two in northeast Ohio on inland reservoirs−to quickly predict action-level exceedances for microcystin, a cyanotoxin commonly found in freshwaters, in recreational and drinking waters used by the public.

This dataset contains a tabular file of phytoplankton abundance and community composition analysis in samples collected from two sites in the Western Lake Erie Basin and one inland lake site in northeast Ohio. Samples were processed by the Ohio Water Microbiology Lab of the U.S. Geological Survey (USGS) and analyzed by BSA Environmental Inc. and during federal fiscal years 2016-2018. The dataset includes phytoplankton taxa (genus and species), division, tally (number of cells counted for each taxa present), density (cells per liter), and total biovolume (cubic micrometers per liter) for each sample collected. These data can be used to assess the community composition of phytoplankton at the sites, identify cyanobacteria species, and determine abundance and biovolume of any known toxin-producing cyanobacteria. The data were part of a larger study, "Predicting microcystin concentration action-level exceedances resulting from cyanobacterial blooms in selected lake sites in Ohio", in which site-specific multiple linear regression models were developed for eight sites in Ohio−six in the Western Lake Erie Basin and two in northeast Ohio on inland reservoirs−to quickly predict action-level exceedances for microcystin, a cyanotoxin commonly found in freshwaters, in recreational and drinking waters used by the public.

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 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.