211— Do Single Cell Cyanobacterial Blooms In Conesus Lake Pose A Risk To Public Health?

Previously unreported blooms dominated by single-celled cyanobacteria have taken place in Conesus Lake, NY since 2015. The dominant bloom organisms are range in size from about 1.0-2.0 μm and are thus referred to as picocyanobacteria. During the summer 2020, a bloom of picocyanobacteria persisted from mid-July to mid-August, reaching peak cell densities of 3.5 x 105 cells/mL. Field samples were filtered through 1.0 micron filters and grown in Alga-Gro liquid culture media at 25oC. Samples were plated in Alga-Gro agar plates and individual colonies were used to grow additional liquid cultures. DNA obtained from these cultures was sequenced and the results were analyzed by Dr. Logan Peoples using bioinformatics techniques. The dominant autotrophs in culture were a previously unreported strain of Synechococcus sp., most closely related to a strain from estuarine waters (15 ppt) in the Chesapeake Bay. The heterotroph Sediminibacterium sp.(Phylum Bacteroidetes) was also present in the sample. Culture samples tested under different salinities grew well at 2.5 ppt and freshwater media controls but not in 5 or 10 ppt media, indicating that the species must live exclusively in freshwater. Experiments to grow monocultures of the heterotrophic species are currently taking place.