Dataset: Hydrogen peroxide influence on toxicity of cyanobacterial harmful algal blooms in Lake Erie

Water samples were collected in the western basin of Lake Erie during the summer and fall of 2017, 2018, and 2019.  In 2017, water was collected approximately weekly from NOAA station WE2 in conjunction with the NOAA Great Lakes Environmental Research Lab (GLERL) harmful algal bloom monitoring program.  During August and October 2017, lake water was also collected by Environment and Climate Change Canada’s monitoring program.  In 2018 and 2019, lake water was collected at several stages of bloom development (pre-bloom, early bloom, late bloom, and post bloom).  In 2018, lake water was collected at NOAA’s monitoring stations WE2 and WE12 and at the drinking water intake for the City of Toledo (TWI).  During summer 2019, the goal was to sample lake waters containing high bloom biomass as predicted by the NOAA HAB forecast model and HAB tracker bulletins (Wynne et al. 2013).  Sampling sites were chosen based on the presence of surface scums comprised of dense cyanobacterial colonies (i.e., “bloom chase” sites).

For all sites, a depth-integrated water sample was collected in acid-washed carboys.  Water samples were collected from the NOAA stations using a peristaltic pump.  The pump hose was moved down the water column from the surface to 1 meter above the bottom.  For the TWI, bloom chase, and Environment Canada cruise sites, a depth-integrated sample was collected by pooling water collected at 1 m intervals from surface to 1 meter above the lake bottom using a Niskin (Environment Canada) or Van Dorn (TWI and bloom chase sites) bottle.  Integrated water samples were stored in carboys in an outdoor aquaculture tank until the start of the bottle experiments the following morning.  The water temperature in the aquaculture tank was controlled using copper piping attached to a NESLAB RTE refrigerated water bath (Thermo Scientific, Newington, NH) and maintained at the lake temperature measured at the time of sample collection.  During the Environment Canada cruises, bottles and carboys were stored in a plexiglass tank continuously circulated with fresh lake water.

Subsamples for supporting water quality analyses were taken from each carboy.  Upon arrival in the laboratory at the University of Michigan, a subsample of whole (unfiltered) water was taken for analysis of total phosphorus.  During 2017, pH of the water from each site was obtained from NOAA monitoring buoys.  For samples collected in 2018-2019, pH of the whole water was measured upon arrival in the laboratory.   Subsamples of the whole water were filtered through a 0.22 μm polyethersulfone (PES) filter for subsequent analysis of total dissolved phosphorus (TDP), soluble reactive phosphorous, nitrate and ammonium, dissolved organic carbon (DOC), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM, respectively).  DOC samples were preserved by addition of 6N trace metal grade hydrochloric acid to pH 3.   TDP, SRP, DOC, CDOM and FDOM were stored in the dark at 4 °C until analysis.  Nitrate and ammonium samples were stored at -20 °C until analysis at GLERL.

Subsamples for H₂O₂ and DNA were collected by filtering 100-200 mL of water from each bottle through a 0.22 μm pore size PES filter and collecting the last 50 mL of filtrate into a centrifuge tube.  The filtered water for H₂O₂ analysis was stored in the dark at 4 °C until analysis within 4 hours of collection.  H₂O₂ concentrations were measured on an FeLume by flow injection analysis using standard additions as previously described (King et al. 2007, as applied to Lake Erie waters in Cory et al. 2017; Pandey et al. 2022).  The filter was saved for DNA extraction by freezing in a cryovial containing 1 mL RNAlater at -80 °C.