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Limnoecology of the freshwater algal genera (excluding diatoms) on Marion Island (sub-Antarctic) / Wilma van Staden.Van Staden, Wilma January 2011 (has links)
The 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 freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, 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 freshwaters are acidic and lakelets 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. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.
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Limnoecology of the freshwater algal genera (excluding diatoms) on Marion Island (sub-Antarctic) / Wilma van Staden.Van Staden, Wilma January 2011 (has links)
The 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 freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, 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 freshwaters are acidic and lakelets 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. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.
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An analysis of selected stakeholder dynamics in the South African recreational freshwater angling sector / by J.J.S. van ZylVan Zyl, Jan Johannes Steyn January 2010 (has links)
Angling as a sport and recreational activity attracts millions of participants worldwide, making it the most popular pastime on the planet. Freshwater bank anglers in South Africa account for approximately 60% of the angling community and contribute billions to the economy.
The freshwater bank angling industry as such is largely informal, with the exception of the small organised angling section. The technical aspects of angling receive an abundance of covering in magazines and increases in popularity through the electronic media. This study focuses on lesser known aspects regarding the angling industry stakeholders and put the activities of South African freshwater bank anglers in perspective. Valuable information was gathered describing the socio-economic profile and various preferences and habits of anglers. The information should form the basis of future studies to formalise the freshwater bank angling industry.
A general and mutual concern among stakeholders for the future sustainability of freshwater angling was identified. The apparent lack of enforcing angling and environmental legislation was singled out as a serious shortcoming in protecting the interests of stakeholders. The study calls for organised angling to engage all stakeholders in a national strategy for developing the structures and creating the momentum to promote and grow this undervalued industry to its potential. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2011.
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An analysis of selected stakeholder dynamics in the South African recreational freshwater angling sector / by J.J.S. van ZylVan Zyl, Jan Johannes Steyn January 2010 (has links)
Angling as a sport and recreational activity attracts millions of participants worldwide, making it the most popular pastime on the planet. Freshwater bank anglers in South Africa account for approximately 60% of the angling community and contribute billions to the economy.
The freshwater bank angling industry as such is largely informal, with the exception of the small organised angling section. The technical aspects of angling receive an abundance of covering in magazines and increases in popularity through the electronic media. This study focuses on lesser known aspects regarding the angling industry stakeholders and put the activities of South African freshwater bank anglers in perspective. Valuable information was gathered describing the socio-economic profile and various preferences and habits of anglers. The information should form the basis of future studies to formalise the freshwater bank angling industry.
A general and mutual concern among stakeholders for the future sustainability of freshwater angling was identified. The apparent lack of enforcing angling and environmental legislation was singled out as a serious shortcoming in protecting the interests of stakeholders. The study calls for organised angling to engage all stakeholders in a national strategy for developing the structures and creating the momentum to promote and grow this undervalued industry to its potential. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2011.
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