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dc.contributor.advisorJanse van Vuuren, Sanet
dc.contributor.advisorSmith, Valdon
dc.contributor.authorVan Staden, Wilma
dc.date.accessioned2014-01-08T06:56:50Z
dc.date.available2014-01-08T06:56:50Z
dc.date.issued2011
dc.identifier.urihttp://hdl.handle.net/10394/9861
dc.descriptionThesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.
dc.description.abstractThe aim of this study was to identify the algal genera found in the different freshwater bodies on Marion Island, to relate the presence or absence of the genera to the chemistry of the water bodies and to group the genera according to their limno-chemical preferences. The Island's freshwater algal genera were also compared with genera found on other Southern Ocean islands. The major factors influencing the chemical composition of the fresh waters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lake lets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lake lets, crater lakes and glacial lakes had low ion and nutrient concentrations, since they are mainly situated inland, away from bird or seal colonies. The chemical composition of wallows was influenced by manuring of seals and seabirds. The fresh waters are acidic and lake lets tend to be more acidic than glacial lakes. The lentic waters were more acidic than the stream. In total, 106 genera, mainly belonging to Chlorophyta (60 genera; 56% of total) and Cyanophyta (29 genera; 27% of total), were found in the freshwaters on the island. Other algal divisions found were Chrysophyta (7 genera), Euglenophyta (4 genera), Pyrrophyta (2 genera) and Xanthophyta (4 genera). Mean number of genera per sample ranged from 8 (in wallows) to 16 (in Eastern Inland lakelets). Filamentous algae were present in all the samples. Abundant green algae were Cosmarium, Klebsormidium, Mougeotia and Oedogonium. The most common cyanobacteria were Lyngbya and Chroococcus. The filamentous yellow-green alga, Tribonema, was also common. There were distinct differences in the algal composition between the southern, western and northern lakelets and the lakelets on the eastern side of the island. Sixty percent of the algal genera were present in waters with low conductivity values. Trichodesmium, Sphaerocystis and Tolypothrix occurred in freshwater bodies with higher conductivity values. Variance analysis showed that 87 of the 106 genera were less likely to occur in nitrogen and phosphate containing waters. Chlamydomonas, Prasiola, Spirogyra Trachelomonas, Tribonema, Ulothrix and Xanthidium were among the genera commonly found in nitrogen and phosphate containing waters. Diversity (number of genera per sample) was negatively correlated with conductivity, PO4-P, NH4-N and NO3-N. Diversity declined significantly with increasing salinity and eutrophication. Genera likely to occur in acidic waters include Binuclearia, Chlamydomonas, Chroococcus, Cosmarium, Klebsormidium, Microspora, Oedogonium, Oocystis, Prasiola, Scenedesmus, Staurastrum, Stigeoclonium, Tetrastrum, Ulothrix, Lyngbya, Synura and Tribonema. Marion Island’s algal flora shows a high affinity with that of Îles Kerguelen and Crozet, both located in the same biogeographical province (South Indian Ocean Province) of the sub-Antarctic than Marion Island, and a lesser affinity with islands in other sub-Antarctic provinces. Algal genera were grouped according to their limno-chemistry preferences.en_US
dc.language.isoenen_US
dc.publisherNorth-West University
dc.subjectAlgaeen_US
dc.subjectMarion Islanden_US
dc.subjectSouth Indian Ocean Provinceen_US
dc.subjectlimnologyen_US
dc.subjectfreshwateren_US
dc.subjectwater chemistryen_US
dc.subjectalgeen_US
dc.subjectSuid Indiese oseaan provinsieen_US
dc.subjectlimnologieen_US
dc.subjectvarswateren_US
dc.subjectchemiese omgewingsveranderlikesen_US
dc.titleLimnoecology of the freshwater algal genera (excluding diatoms) on Marion Island (sub–Antarctic)en
dc.typeThesisen_US
dc.description.thesistypeMastersen_US


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