Cyanotoxins, Chlorophyll-a, and Phytoplankton Assemblage Data for Lake Ontario and Surrounding Tributaries, New York State, April to October 2023

This data release contains field measurements and discrete surface water sample results for parameters related to the assessment of harmful algal blooms. Field measurements include fluorescent chlorophyll, phycocyanin fluorescence, and photosynthetically active radiation (PAR). Discrete water samples were analyzed for extracted chlorophyll-a and pheophytin-a concentrations, total cyanotoxin concentrations (microcystin, anatoxin, saxitoxin, cylindrospermopsin), and phytoplankton assemblages.

Cyanotoxins were determined using enzyme-linked immunosorbent assay (ELISA) methods. Phytoplankton were identified to the lowest possible taxonomic level, and abundance reported as both natural units and cells, along with estimates of biovolume.

Sampling occurred from April to October 2023 for field measurements and from May to October 2023 for discrete samples. Thirty-five sites were sampled along the south shore of Lake Ontario in New York — including nearshore areas, embayments, and tributaries — from the Niagara River to Chaumont Bay. Nearshore and embayment samples were collected by peristaltic pump at wadable depths into a churn splitter. Tributary samples were collected using the Equal Discharge Increment (EDI) method. PAR measurements were not made at tributary sites and phytoplankton samples were not collected in October 2023. A shape file of sample site locations is included. Field replicates and field blanks are included for quality assurance and quality control evaluation.