Buoyancy and suspension of planktonic cyanobacteria

Murray-Darling Freshwater Research Centre

MDFRC item.

Cyanobacteria are unique among phytoplankton in their ability to controltheir depth in lakes by buoyancy regulation. They derive their buoyancyfrom gas vesicles, which if present in sufficient quantity will offsetthe excess buoyant density of other cell constituents. Cyanobacteria mayregulate buoyancy by one, or more, of three mechanisms: gas vesiclecollapse; regulation of gas vesicle formation; or changes in other components,especially carbohydrate. This chapter describes the techniquesdeveloped to elucidate the mechanisms of buoyancy regulation in laboratorycultures and to study the phenomena of vertical migration or stratificationby cyanobacteria in lakes.