A study on periphyton as indicator of water-quality in regulated rivers
| dc.contributor.advisor | Seaman, M. T. | |
| dc.contributor.advisor | Van Ginkel, C. E. | |
| dc.contributor.advisor | Scott, W. E. | |
| dc.contributor.author | Vos, Adriana Tascha | |
| dc.date.accessioned | 2016-02-19T10:30:40Z | |
| dc.date.available | 2016-02-19T10:30:40Z | |
| dc.date.issued | 2015-01 | |
| dc.description.abstract | In the central part of South Africa, where the average rainfall is 400–600 mm/yr and evaporation far exceeds precipitation, it is important to monitor the limited freshwater resources that are available and to keep the aquatic environment in an acceptable state. Excessive nutrients (N and P) lead to algal blooms and deterioration of other aquatic biota as the water quality declines. Biological monitoring methods and programmes have been instrumental in the management and monitoring of the health of aquatic ecosystems. Various biomonitoring indices have been developed, using fish, benthic macroinvertebrates, phytoplankton and periphyton (including Bacillariophyta), as site- or non-site-specific indicators of water quality. Periphyton forms the foundation of many food webs. It is adaptable to the availability of a habitat and is directly affected by changes in water quality. In unregulated rivers, “normal” flow patterns and disturbance regimes shape the benthic community composition, while in regulated rivers the “unpredictability” of flow (as an example) adds extra stress to the ecosystem. The overall objective of this study was to determine the position of periphyton (as a group) as a biomonitoring tool and which of its components would be best suited as indicators of water quality. This study was carried out over two periods of 24 months each at two sites on the Modder River and one on the Renoster Spruit. The sites were selected because SASS5 (standard benthic macroinvertebrate index of water quality) could be carried out on “stones in current”, as this is the preferred habitat for sampling periphyton. The physical and chemical factors sampled were temperature (°C), turbidity (NTU), flow (m/s), dissolved oxygen (mg/ℓ and % saturation), electrical conductivity (μS/cm) and total dissolved salts (mg/ℓ), pH, redox potential (mV), nutrients (including dissolved inorganic phosphorus and nitrogen) and chlorophyll-a. The biotas sampled were periphyton, phytoplankton and benthic macroinvertebrates. Statistical analyses were carried out on all sampled data. Correlations and patterns between the periphyton values and the physical, chemical and biological conditions were investigated. The effect of seasonality on the periphyton and the influence of hydrological phases (dry and wet periods) on the periphyton were examined. Results indicate that the composition of the periphyton is shaped by seasons. An increase of Bacillariophyta was found during winter, and Chlorophyta and Cyanophyta during summer. The increase of flow during wet periods had a negative effect on the biovolume of periphyton, as fewer filamentous and colonial algae were present during the wet period. The cell and chlorophyll-a concentration also decreased because of dislodgement during high flow. Even though the nutrients had an influence on all the periphytic algal components, the best correlations were found with the periphytic chlorophyll-a concentration. The periphyton composition and concentration were compared to the biomonitoring indices used on the sampled rivers and sites, namely FRAI (fish) and SASS5 (benthic macroinvertebrates), as well as phytoplankton. To conclude, it was found that periphyton could be used as a biomonitoring indicator in the monitoring and management of water quality. However, as the standard biomonitoring indices operate on different spatial scales and measures, the best results would be obtained if all, or a combination of indices, were used. | en_ZA |
| dc.description.abstract | Afrikaans: In die sentrale deel van Suid-Afrika, waar die gemiddelde reënval 400– 600 mm/jaar is en verdamping die neerslag ver oorskry, is dit belangrik om die beperkte varswaterbronne wat daar is te monitor en die akwatiese omgewing in 'n goeie toestand te hou. Oormatige voedingstowwe (N en P) lei tot algopbloeie en die verswakking van ander waterbiota namate die gehalte van die water afneem. Die ontwikkeling van biologiese moniteringsmetodes en programme is instrumenteel om die gesondheid van water-ekosisteme te bestuur en te monitor. Verskeie biomoniteringsindekse is ontwikkel met die gebruik van vis, bentiese makroinvertebrate, fitoplankton en perifiton (insl. Bacillariophyta), as plek- of nieplekspesifieke aanwysers van watergehalte. Perifiton vorm die grondslag van baie voedselwebbe. Dit is aanpasbaar by die beskikbaarheid van 'n habitat en word direk geraak deur die verandering in die waterkwaliteit. In ongereguleerde riviere vorm "normale" vloei- en versteuringspatrone die samestelling van die bentiese gemeenskap, terwyl die "onvoorspelbaarheid" van vloei (as 'n voorbeeld) ekstra stremming op die ekosisteem in gereguleerde riviere plaas. Die oorhoofse doel van hierdie studie was om die posisie van perifiton (as 'n groep) as 'n biomoniteringsinstrument te ondersoek, asook watter van die perifitonkomponente die geskikste is as indikatore van watergehalte. Hierdie studie is oor twee periodes van 24 maande elk uitgevoer, op twee plekke op die Modderrivier en een op die Renosterspruit. Die terreine is gekies omdat SASS5 (standaard bentiese makroinvertebraatindeks van waterkwaliteit) gedoen kan word met "klippe in die stroom". Klippe is die voorkeurhabitat vir perifitonversameling. Die fisiese en chemiese faktore wat versamel is, is temperatuur (°C), troebelheid (NTU), vloei (m/s), opgeloste suurstof (mg/ℓ en % versadiging), elektriese geleiding (μS/cm) en totale opgeloste soute (mg/ℓ), pH, redokspotensiaal (mV), voedingstowwe (insluitende opgeloste anorganiese fosfor en stikstof) en chlorofil-a. Die versamelde biotas was perifiton, fitoplankton en bentiese makroinvertebrate. Statistiese ontledings is op al die versamelde data uitgevoer. Korrelasies en patrone tussen die perifitonwaardes en dié van die fisiese, chemiese en biologiese faktore is ondersoek. Die effek van die seisoene op die perifiton en die invloed van hidrologiese fases (droë en nat periodes) op perifiton is ondersoek. Resultate dui aan dat die samestelling van die perifiton deur seisoene gevorm word. 'n Toename van Bacillariophyta is gedurende die winter, en Chlorophyta en Cyanophyta gedurende die somer waargeneem. Die toename van vloei gedurende nat periodes het 'n negatiewe uitwerking op die biovolume van perifiton – daar was minder filamentagtige en kolonie-vormende alge teenwoordig tydens die nat tydperk. Daar is ook ʼn afname in die sel- en chlorofil-a konsentrasie deur middel van verdrywing. Al het die voedingstowwe 'n invloed op al die perifitiese algkomponente, is die beste korrelasie gevind met die perifitiese chlorofil-a konsentrasie. Die perifitonsamestelling en -konsentrasie is ook vergelyk met die biomoniteringsindekse wat op die steekproef-riviere en -terreine gebruik word, naamlik FRAI (vis) en SASS5 (bentiese makroinvertebrate), asook met fitoplankton. Om af te sluit, is daar gevind dat perifiton as 'n biomoniteringsindikator in die monitering en bestuur van watergehalte gebruik kan word. Omdat die standaard biomoniteringsindekse egter op verskillende ruimtelike skale werk en verskillende aspekte meet, sal die beste resultate verkry word indien alle, of ʼn kombinasie van indekse, saam gebruik word. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/2336 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Periphyton | en_ZA |
| dc.subject | Epilithic | en_ZA |
| dc.subject | Biomonitoring | en_ZA |
| dc.subject | Water quality | en_ZA |
| dc.subject | Chlorophyll-a | en_ZA |
| dc.subject | Regulated rivers | en_ZA |
| dc.subject | SASS5 | en_ZA |
| dc.subject | Seasonal | en_ZA |
| dc.subject | Hydrological phases | en_ZA |
| dc.subject | Indicator indices | en_ZA |
| dc.subject | Thesis (Ph.D. (Centre for Environmental Management))--University of the Free State, 2015 | en_ZA |
| dc.subject | Aquatic ecology | en_ZA |
| dc.subject | Rivers -- Regulation -- Environmental aspects | en_ZA |
| dc.title | A study on periphyton as indicator of water-quality in regulated rivers | en_ZA |
| dc.type | Thesis | en_ZA |