Keith A. Loftin Jennifer L. Graham Katherine N. Stahlhut James M. Riley Brett D. Johnston Sarena Senegal Barry H. Rosen 2018 <p>In an effort to simulate the survival of cyanobacteria as<br>they are transported from Lake Okeechobee to the estuarine<br>habitats that receive waters from the lake, a bioassay<br>encompassing a range of salinities was performed. An overall<br>decline in cyanobacteria health in salinity treatments greater<br>than 18 practical salinity units (psu) was indicated by loss of<br>cell membrane integrity based on SYTOX® Green staining,<br>but this loss varied by the kind of cyanobacteria present.<br>Microcystis aeruginosa was tolerant of salinities up to 18 psu;<br>however, higher salinities caused leaking of microcystin from<br>the cells. Dolichospermum circinale, another common bloomformer<br>in this system, did not tolerate salinities greater than<br>7.5 psu. Stimulation of mucilage production was observed and<br>is likely a mechanism used by both species to protect organism<br>viability. At 7.5 psu, microcystin increased relative to<br>chlorophyll-a, providing some evidence of biosynthesis when<br>M. aeruginosa is exposed to this salinity. This study indicates<br>that as freshwater cyanobacteria are transported to brackish<br>and marine waters, there will be a loss of membrane integrity<br>which will lead to the release of cellular microcystin into the<br>surrounding waterbody. Additional research would be needed<br>to determine the exact effect of salinity on this relationship.</p> application/pdf 10.3133/sir20185092 en U.S. Geological Survey Understanding the effect of salinity tolerance on cyanobacteria associated with a harmful algal bloom in Lake Okeechobee, Florida reports