title: Beating the blues: is there any music in fighting cyanobacteria with ultrasound?
abstract: The hypothesis that cyanobacteria can be controlled by commercially available ultrasound transducers was tested in laboratory experiments with cultures of the cyanobacteria Anabaena sp., Cylindrospermopsis raciborskii and Microcystis aeruginosa and the green alga Scenedesmus obliquus that were grown in the absence or presence of ultrasound (mix of 20, 28 and 44 kHz). The Scenedesmus experiment also included a treatment with the zooplankton grazer Daphnia magna. Chlorophyll-a and biovolume-based growth of Anabaena was significantly lower in ultrasound exposed cultures than in controls. Particle based growth rates were higher in ultrasound treatments. Filaments were significantly shorter in ultrasound exposed cultures reflecting filament breakage. Photosystem II efficiency was not affected by ultrasound. In Cylindrospermopsis chlorophyll-a based growth rates and photosystem II efficiencies were similar in controls and ultrasound treatments, but biovolume-based growth was significantly lower in ultrasound exposed cultures compared to controls. Despite biovolume growth rates of the filamentous cyanobacteria were reduced in ultrasound treatments compared to controls, growth remained positive implying still a population increase. In Microcystis and Scenedesmus growth rates were similar in controls and ultrasound treatments. Hence, no effect of ultrasound on these phytoplankton species was found. Ultrasound should not be viewed "environmental friendly" as it killed all Daphnia within 15 min, releasing Scenedesmus from grazing control in the cultures. Based on our experiments and critical literature review, we conclude that there is no music in controlling cyanobacteria in situ with the commercially available ultrasound transducers we have tested.
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB Wageningen, The Netherlands. Electronic address: miquel.lurling@wur.nl.
authors.forename: Miquel
authors.initials: M
authors.lastname: Lürling
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Regional Water Authority Delfland, P.O. Box 3061, 2061 DB Delft, The Netherlands.
authors.forename: Yora
authors.initials: Y
authors.lastname: Tolman
mesh_terms: D017033:Anabaena; D000818:Animals; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000378:metabolism*; D046891:Cylindrospermopsis; D003621:Daphnia; D006863:Hydrogen-Ion Concentration; D046931:Microcystis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010839:Phytoplankton; D044444:Scenedesmus; D014465:Ultrasonics; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Anabaena; Blooms; Cylindrospermopsis; Eutrophication control; Microcystis; Mitigation