Phytoplankton yield changes after enrichment in microcosm experiments: applications for predicting progressive eutrophication in a mesotrophic lake, South Africa

dc.contributor.authorOberholster, Paul Johan
dc.contributor.authorAshton, Peter J.
dc.contributor.authorBotha, Anna-Maria
dc.contributor.authorKleynhans, C.J.
dc.date.accessioned2013-04-19T08:34:34Z
dc.date.available2013-04-19T08:34:34Z
dc.date.issued2012-11-08
dc.description.abstractEstablished microcosms containing surface water from the mesotrophic Lake Mokolo were subjected to enrichment of different concentrations with phosphorus. The microcosms were sampled through a 20 day succession period to determine the net effects of increased concentrations of phosphorus in the water column on the phytoplankton community structure during the winter and summer seasons. A significant increase in chlorophyll a (chl-a) was observed when treatments of 30, 40 and 60 μg L-1 P were compared to the controls. On day zero in both the winter and summer microcosm experiments, all four phosphorus treatments had similar species diversity of phytoplankton of the specific seasoned tested (winter: Margalef index = 223; summer: Margalef index = 347). However, 13 days after the addition of 40 and 60 μg L-1 P, the phytoplankton community exhibited a strikingly different species richness (winter: Margalef index = 123; summer: Margalef index = 114). In the winter microcosm experiments, the green alga Scenedesmus armatus dominated the phytoplankton composition at enrichment levels of 40 and 60 μg L-1 P up to day 20. The biovolume of the dinophyceae Ceratium hirundinella declined rapidly after the addition of 40 μg L-1 P in the different summer microcosms. In the summer microcosms, Spondylosium secedens and Microcystis aeruginosa dominated the 40 and 60 μg L-1 P microcosm enrichment experiments.en
dc.description.librarianam2013en
dc.description.librarianmn2013
dc.description.urihttp://www.academicjournals.org/AJBen
dc.format.extent12 pagesen
dc.format.mediumPDFen
dc.identifier.citationOberholster, PJ, Ashton, PJ, Botha, AM & Kleynhans, CJ 2012, 'Phytoplankton yield changes after enrichment in microcosm experiments: applications for predicting progressive eutrophication in a mesotrophic lake', South Africa', African Journal of Biotechnology, vol. 11, no. 90, pp. 15678-15689.en
dc.identifier.issn1684-5315
dc.identifier.other10.5897/AJB11.3170
dc.identifier.urihttp://hdl.handle.net/2263/21326
dc.language.isoenen
dc.publisherAcademic Journalsen
dc.rights©2012 Academic Journalsen
dc.subjectScenedesmus armatusen
dc.subjectSouthern Hemisphere lakeen
dc.subjectCyanobacteriaen
dc.subjectThreshold phosphorus concentrationsen
dc.subjectChlorophyll a (chl-a) concentrationen
dc.subject.lcshMicrocosm and macrocosmen
dc.titlePhytoplankton yield changes after enrichment in microcosm experiments: applications for predicting progressive eutrophication in a mesotrophic lake, South Africaen
dc.typeArticleen

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