dc.contributor.author |
Zohary, T
|
|
dc.contributor.author |
Pais-Madeira, AM
|
|
dc.contributor.author |
Robarts, RD
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|
dc.contributor.author |
Hambright, KD
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|
dc.date.accessioned |
2007-06-29T06:13:50Z |
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dc.date.available |
2007-06-29T06:13:50Z |
|
dc.date.issued |
1995 |
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dc.identifier.citation |
Zohary, T, et al. 1995. Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake. Water Science and Technology, vol. 32(4), pp 103-104 |
en |
dc.identifier.issn |
0273-1223 |
|
dc.identifier.uri |
http://hdl.handle.net/10204/725
|
|
dc.description |
Copyright: 1995 Pergamon-Elsevier Science Ltd |
en |
dc.description.abstract |
Phytoplankton species composition and abundance were recorded weekly or biweekly for nearly 7 years in a hypertrophic lake ( Hartbeespoort Dam, South Africa), together with a range of physical and chemical parameters. A total of 73 species were recorded, of which only 20 were occasionally abundant, and only 5 became dominant (>50% of total biomass) at least once (Microcystis aeruginosa, Oocystis lacustris, Aulacoseira (= Melosira) granulata, Cyclotella meneghiniana, Carteria cordiformis). The earlier years of the study (1982-1986) were drought years characterized by low water levels (10-15 m below the level at full supply), excess supply of nutrients at all times of the year, and overwhelming dominance of Microcystis aeruginosa. This K-selected species proved to be well adapted to withstand the range of environmental conditions throughout summer, fall and winter but it declined in spring each year when a fast successional episode followed. Several small-celled chlorophytes, diatoms and cryptophytes appeared and disappeared until Oocystis lacrustris became dominant for a few weeks, to be replaced by M. aeruginosa early in the summer. During the following rainy years (late 1986 to 1988), the lake re-filled. Major washout losses, concomitant with a considerable decline in surface water phosphorus concentrations and elevated TN/TP ratios, apparently led to the reduction in the abundance of M. aeruginosa. Its bloom extended over a smaller portion of the year in 1986 and 1987, and disappeared in May 1988, permitting the development of a more diverse phytoplankton community subject to control by 2ooplankton grazing. This long-term phytoplankton record from Hartbeespoort Dam demonstrates the key role of a dominant species in controlling community composition and diversity in hypertrophic lakes. Stable environments lead to low-diversity and high-biomass phytoplankton assemblages dominated by K-strategists, while disruptions of suitable strength and frequency allow for the development and maintenance of higher species diversity. |
en |
dc.language.iso |
en |
en |
dc.publisher |
Pergamon-Elsevier Science Ltd |
en |
dc.subject |
Haartebeesport dam |
en |
dc.subject |
Species composition |
en |
dc.subject |
Microcystis aeruginosa |
en |
dc.subject |
Oocystis lacustris |
en |
dc.subject |
Competitive exclusion |
en |
dc.title |
Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake |
en |
dc.type |
Article |
en |
dc.identifier.apacitation |
Zohary, T., Pais-Madeira, A., Robarts, R., & Hambright, K. (1995). Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake. http://hdl.handle.net/10204/725 |
en_ZA |
dc.identifier.chicagocitation |
Zohary, T, AM Pais-Madeira, RD Robarts, and KD Hambright "Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake." (1995) http://hdl.handle.net/10204/725 |
en_ZA |
dc.identifier.vancouvercitation |
Zohary T, Pais-Madeira A, Robarts R, Hambright K. Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake. 1995; http://hdl.handle.net/10204/725. |
en_ZA |
dc.identifier.ris |
TY - Article
AU - Zohary, T
AU - Pais-Madeira, AM
AU - Robarts, RD
AU - Hambright, KD
AB - Phytoplankton species composition and abundance were recorded weekly or biweekly for nearly 7 years in a hypertrophic lake ( Hartbeespoort Dam, South Africa), together with a range of physical and chemical parameters. A total of 73 species were recorded, of which only 20 were occasionally abundant, and only 5 became dominant (>50% of total biomass) at least once (Microcystis aeruginosa, Oocystis lacustris, Aulacoseira (= Melosira) granulata, Cyclotella meneghiniana, Carteria cordiformis). The earlier years of the study (1982-1986) were drought years characterized by low water levels (10-15 m below the level at full supply), excess supply of nutrients at all times of the year, and overwhelming dominance of Microcystis aeruginosa. This K-selected species proved to be well adapted to withstand the range of environmental conditions throughout summer, fall and winter but it declined in spring each year when a fast successional episode followed. Several small-celled chlorophytes, diatoms and cryptophytes appeared and disappeared until Oocystis lacrustris became dominant for a few weeks, to be replaced by M. aeruginosa early in the summer. During the following rainy years (late 1986 to 1988), the lake re-filled. Major washout losses, concomitant with a considerable decline in surface water phosphorus concentrations and elevated TN/TP ratios, apparently led to the reduction in the abundance of M. aeruginosa. Its bloom extended over a smaller portion of the year in 1986 and 1987, and disappeared in May 1988, permitting the development of a more diverse phytoplankton community subject to control by 2ooplankton grazing. This long-term phytoplankton record from Hartbeespoort Dam demonstrates the key role of a dominant species in controlling community composition and diversity in hypertrophic lakes. Stable environments lead to low-diversity and high-biomass phytoplankton assemblages dominated by K-strategists, while disruptions of suitable strength and frequency allow for the development and maintenance of higher species diversity.
DA - 1995
DB - ResearchSpace
DP - CSIR
KW - Haartebeesport dam
KW - Species composition
KW - Microcystis aeruginosa
KW - Oocystis lacustris
KW - Competitive exclusion
LK - https://researchspace.csir.co.za
PY - 1995
SM - 0273-1223
T1 - Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake
TI - Cyanobacteria-phytoplankton dynamics of a hypertrophic African lake
UR - http://hdl.handle.net/10204/725
ER -
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en_ZA |