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).

Quantitative phytoplankton data was collected as part of an interdisciplinary and multiagency experimental study investigating harmful algal bloom (HAB) dynamics in the Caloosahatchee River located in southwestern Florida. Algae and cyanobacteria play crucial roles in aquatic ecosystems, but under favorable environmental conditions such as nutrient enrichment certain taxa may experience population growth booms resulting in HABs. HABs are becoming increasing common in the Caloosahatchee and the Lake Okeechobee system, yet the drivers and processes controlling these events is still under investigation. Here, three independent mesocosm experiments were conducted on the Caloosahatchee River at the W. P. Franklin Lock and Dam, Florida, in February 2021, May 2021, and July 2021 to test the effects of nutrient enrichment of phytoplankton assemblage structure at different times in the year 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 five treatments: phosphate (P), nitrate (N), urea (U), ammonium (A), or control (C). Only four of the five treatments were selected for a given experiment: February 2021 treatments included P, N, A, and C, May 2021 treatments included P, U, A, and C, and July 2021 treatments included U, N, A, and C. The P, N, U, and A treatment chambers were enriched in the appropriate nutrient by applying a concentrated dosing solution of either dibasic dodecahydrate sodium phosphate, anhydrous sodium nitrate, solid crystal urea, or liquid ammonium hydroxide respectively to elevate concentrations above ambient levels. The mesocosms were treated and sampled approximately every 24 hours over a 72-hour period (Time 0, Time 24, Time 48, Time 72). May and July 2021 mesocosm were also sampled a week from the initial dosing (T240). Water quality, phytoplankton, cyanotoxin, and environmental DNA (eDNA) samples were collected before and after dosing each day. The current dataset contains only the phytoplankton data including absolute and relative abundance measures at the genus to species level as natural units (NU/mL), cell densities (cells/mL), and biovolumes (um3/mL).

Quantitative phytoplankton data was collected as part of an interdisciplinary and multiagency experimental study investigating harmful algal bloom (HAB) dynamics in the Caloosahatchee River located in southwestern Florida. Algae and cyanobacteria play crucial roles in aquatic ecosystems, but under favorable environmental conditions such as nutrient enrichment certain taxa may experience population growth booms resulting in HABs. HABs are becoming increasing common in the Caloosahatchee and the Lake Okeechobee system, yet the drivers and processes controlling these events is still under investigation. Here, three independent mesocosm experiments were conducted on the Caloosahatchee River at the W. P. Franklin Lock and Dam, Florida, in February 2021, May 2021, and July 2021 to test the effects of nutrient enrichment of phytoplankton assemblage structure at different times in the year 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 five treatments: phosphate (P), nitrate (N), urea (U), ammonium (A), or control (C). Only four of the five treatments were selected for a given experiment: February 2021 treatments included P, N, A, and C, May 2021 treatments included P, U, A, and C, and July 2021 treatments included U, N, A, and C. The P, N, U, and A treatment chambers were enriched in the appropriate nutrient by applying a concentrated dosing solution of either dibasic dodecahydrate sodium phosphate, anhydrous sodium nitrate, solid crystal urea, or liquid ammonium hydroxide respectively to elevate concentrations above ambient levels. The mesocosms were treated and sampled approximately every 24 hours over a 72-hour period (Time 0, Time 24, Time 48, Time 72). May and July 2021 mesocosm were also sampled a week from the initial dosing (T240). Water quality, phytoplankton, cyanotoxin, and environmental DNA (eDNA) samples were collected before and after dosing each day. The current dataset contains only the phytoplankton data including absolute and relative abundance measures at the genus to species level as natural units (NU/mL), cell densities (cells/mL), and biovolumes (um3/mL).

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).

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).

The dataset consists of results from two stream mesocosm experiments that were conducted in the summer-autumn of 1996 and 1997 to distinguish the influence of fine sediment loads and nutrient concentrations on benthic macro-invertebrate and algal communities. 11 biological variables were extracted from the results of this experiment and were standardized for the purpose of training neural networks that could be used to diagnose nutrient and fine sediment impacts in field surveys. The 11 variables were selected according to how well they correlated with the experimental treatment levels (high and low values of both nutrients and fine sediments). The 11 variables were: chlorophyll a (mg/m2), macro-invertebrate familial richness, total abundance, and the abundance of Oligochaeta, Leptoperla varia (Gripopterygidae), Nousia spp. (Leptophlebiidae), Austrophlebioides spp. (Leptophlebiidae), Orthocladiinae, Tanypodinae, Tipulidae and larval Scirtidae. These taxa were abundant within and among the stream mesocosm communities and are common in a wide range of Tasmanian rivers. Values for each of 11 biological response variables were standardized by dividing by their average value observed in the experimental controls mesocosm samples from that year. See Magierowski RH, Read SM, Carter SJB, Warfe DM, Cook LS, Lefroy EC, et al. (2015) Inferring Landscape-Scale Land-Use Impacts on Rivers Using Data from Mesocosm Experiments and Artificial Neural Networks. PLoS ONE 10(3): e0120901. https://doi.org/10.1371/journal.pone.0120901 https://doi.org/10.1371/journal.pone.0120901. This data was collected for the purpose of training artificial neural networks that could diagnose nutrient and sediment impacts in Tasmanian rivers. Each of the 11 variables were standardized by their average value observed in the experimental control samples from that year and some experimental treatment effects (Light) were ignored to simplify the neural network training process. Therefore, these data should not be used to make conclusions about the impacts of fine sediments and nutrients in Tasmanian rivers.

These data have been collected as part of a cooperative project between the U.S. Geological Survey (USGS) and the U.S Environmental Protection Agency. This project began in 2016 and consisted of a mesocosm experiment quantifying short term responses by a transplanted natural diatom dominant algae community exposed to gradients of nitrogen, phosphorous, and a mixture of both nitrogen and phosphorus. The data consist of water quality parameters such as temperature and pH as well as aqueous nutrient concentrations and algae responses, including chlorophyll a concentrations, algae dry mass, algae ash-free dry mass, and intra-cellular phosphorus and nitrogen in algae. Algae growth rates were estimated from these data and are meant to be used with water-quality models; the results of this investigation can be found in the manuscript associated with this data release (Schmidt and others 2019).

These data have been collected as part of a cooperative project between the U.S. Geological Survey (USGS) and the U.S Environmental Protection Agency. This project began in 2016 and consisted of a mesocosm experiment quantifying short term responses by a transplanted natural diatom dominant algae community exposed to gradients of nitrogen, phosphorous, and a mixture of both nitrogen and phosphorus. The data consist of water quality parameters such as temperature and pH as well as aqueous nutrient concentrations and algae responses, including chlorophyll a concentrations, algae dry mass, algae ash-free dry mass, and intra-cellular phosphorus and nitrogen in algae. Algae growth rates were estimated from these data and are meant to be used with water-quality models; the results of this investigation can be found in the manuscript associated with this data release (Schmidt and others 2019).

This report documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta in the Sacramento-San Joaquin River Delta of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll. Data-collection were conducted over one day in July 2017 when continuous monitoring stations detected elevated chlorophyll concentration and decreasing nitrate concentrations.

This report documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta in the Sacramento-San Joaquin River Delta of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll. Data-collection were conducted over one day in July 2017 when continuous monitoring stations detected elevated chlorophyll concentration and decreasing nitrate concentrations.