Search
Search results for
We found
42 results for you
-
THE SUMMER CONDITION OF THREE EASTERN TRANSVAAL RESERVOIRS AND SOME CONSIDERATIONS REGARDING THE ASSESSMENT OF TROPHIC STATUS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Walmsley --- , South Africa D.F. Toerien --- , South AfricaSummer temperature, oxygen and light penetration profiles in the Da Gama, Klipkopje and Witklip Reservoirs are presented. Analysis of waters from different depths showed the presence of chemical stratification despite the absence of clear thermal stratification. An algal bioassay procedure... -
THE LIMNOLOGY OF SOME SOUTH AFRICAN IMPOUNDMENTS I. THE PHYSICO-CHEMICAL LIMNOLOGY OF HARTBEESPOORT DAM
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: W.E. Scott --- , South Africa M.T. Seaman --- , South Africa A.D. Connell --- , South Africa S.I. Kohlmeyer --- , South Africa D.F. Toerien --- , South AfricaHartbeespoort Dam is a eutrophic, warm monomictic lake with overturn occurring in April. The lake is stratified for about six months of the year and in late summer the stratification appears stable. Light penetration in the dam depends both on... -
AN INTRODUCTION TO THE LIMNOLOGY OF ROODEPLAAT DAM
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Walmsley --- , South Africa D.F. Toerien --- , South Africa D.J. Steÿn --- , South AfricaA two-year limnological survey between 1973 and 1975 showed that the Roodeplaat Dam is a warm monomictic impoundment which has stable thermal stratification during summer. Oxygen supersaturation of the surface waters and anaerobic conditions in the hypolimnion were encountered during... -
THE OCCURRENCE OF MICROCYSTIS AERUGINOSA IN THE BOTTOM SEDIMENTS OF A SHALLOW EUTROPHIC PAN
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: M. Tow --- Department of Botany and Microbiology, South AfricaSediment samples, collected from Jan Smuts Park Dam in Brakpan, Transvaal, during winter months were incubated in culture medium in the laboratory and found to contain viable Microcystis aeruginosa Kütz. emend. Elenkin colonies. The results obtained, indicate that the alga... -
A PRELIMINARY LIMNOLOGICAL STUDY OF BUFFELSPOORT DAM AND ITS CATCHMENT
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Walmsley --- , D.F. Toerien --- ,A limnological survey of the Buffelspoort Dam and its catchment between 1973 and 1975 showed that the water of the area contained extremely low concentrations of dissolved minerals and that there was no point source of nutrient supply to the... -
LIMNOLOGICAL MODELLING: SIMULATION OF VERTICAL PROFILES OF TEMPERATURE, DISSOLVED OXYGEN AND NUTRIENTS. I. THEORY
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: B. Henderson-Sellers --- Department of Civil Engineering, United KingdomIn a body of water, variations occur in all limnological parameters on many time and space scales. Modelling can either be specific - for a selected subset; or can attempt to simulate the gross characteristics of e.g. current, temperature, algal... -
THE USE OF TROFIC AS AN AID FOR THE MANAGEMENT OF EUTROPHIC LAKES
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: K. Clarke --- , A.C. Jarvis --- , P.J. Ashton --- , T. Zohary --- ,As a result of eutrophication studies that have been performed by the National Institute for Water Research for many years it was decided in 1980 that a detailed investigation into this area take place. Hypertrophic Hartbeespoort Dam was selected as... -
FUTURE CHALLENGES IN WATER QUALITY MODELLING WITH PARTICULAR REFERENCE TO OPERATIONALLY CLOSED CATCHMENTS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: S.F. Forster --- Department of Water Affairs, South Africa F.A. Stoffberg --- Department of Water Affairs, South Africa J.A. van Rooyen --- Department of Water Affairs, South AfricaAs a result of the declining quality of many water sources, the use of water quality models in planning is increasing. To date applications have involved the simulation of total dissolved salts and nutrients, largely in catchments affected by urban... -
ASPECTS OF EUTROPHICATION MANAGEMENT IN TROPICAL/SUB-TROPICAL REGIONS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: J.A. Thornton --- , South AfricaIn 1981, the UNESCO in association with the IIASA and OECD recognized that tropical/-sub-tropical water bodies may respond differently to eutrophication management techniques than heretofore expected on the basis of temperate lake studies. However, little information on the eutrophication process... -
MANAGEMENT OPTIONS FOR SHALLOW HYPERTROPHIC LAKES, WITH PARTICULAR REFERENCE TO ZEEKOEVLEI, CAPE TOWN
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: W.R. Harding --- , South Africa A. J.R. Quick --- , South AfricaZeekocvlei, a freshwater coastal lake, is an important regional recreation area in the south-western Cape, South Africa. The lake is hypertrophic, experiences perenially dense populations of cyanobacteria (Microcystis), invasive bulrush and reed encroachment, and has a thick benthic layer of... -
CHANGES IN THE BENTHIC FAUNA OF LAKE CHIVERO, ZIMBABWE, OVER THIRTY YEARS
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: B.E. Marshall --- Department of Biological Sciences, ZimbabweLake Chivero is a eutrophic Zimbabwean reservoir and data on its benthic fauna are available over a period of about thirty years. The levels of organic carbon are higher than in many other southern African reservoirs but have not increased... -
Towards the assessment of the trophic status of South African impoundments for management purposes: Bon Accord Dam
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: CE van Ginkel BC Hohls E VermaakThe 1 mg/l phosphate effluent standard legislated in South Africa in 1980 in seven sensitive catchments, and ad hoc eutrophication-related requests, necessitated the monitoring of 53 impoundments throughout the country. Variables that were monitored, and are still being monitored in... -
Beacons in the limnological landscape
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: BR AllansonAn overview is given of a number of major developments in the limnology of South Africa, Zimbabwe and Namibia. None was possible without the involvement of enthusiastic investigators who, over some 70 years, stimulated the growth of freshwater research in... -
The phytoplankton of Great Bitter Lake, Egypt, including the impacts of nutrient-laden and heated effluents
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: HusseinE Touliabah WilliamD TaylorA year-long survey of the phytoplankton and nutrients in Great Bitter Lake indicates that this is a severely eutrophic lake. Chlorophyll levels were consistently high (>30μg/l), especially in summer (>90μg/l). The phytoplankton community comprised mostly diatoms and blue-green algae, although... -
The response of Cyperus papyrus (L.) and Miscanthidium violaceum (K. Schum.) Robyns to eutrophication in natural wetlands of Lake Victoria, Uganda
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: J Kipkemboi --- Department of Zoology, Kenya F Kansiime --- , Uganda P Denny --- , The NetherlandsInterrelationships between nutrient concentrations and aerial biomass, root numbers, length and rhizomes size in Cyperus papyrus (L.) (papyrus) and Miscanthidium violaceum (K. Schum.) Robyns (synonymous to Miscanthus violaceus (K. Schum) Pilg.) were established in five different wetlands around the northern... -
Spatial and temporal patterns of phytoplankton abundance and composition in three ecological zones in the Tanzanian waters of Lake Victoria
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: GW Ngupula --- , Tanzania ASE Mbonde --- , Tanzania CN Ezekiel --- , TanzaniaPhytoplankton abundance and composition in relation to physico-chemical parameters were investigated from September 2005 to October 2007 at 51 stations of various depths in the nearshore, intermediate and deep offshore waters of Lake Victoria. Shallow nearshore waters had the highest... -
Zooplankton abundance and composition in the hypertrophic Rietvlei Dam, South Africa, negate prospects for its remedial ‘top-down’ biomanipulation
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: RC Hart --- School of Life Sciences, South AfricaCrustacean zooplankton abundance and composition were determined at one offshore and three nearshore sites in the hypertrophic Rietvlei Dam on 19 dates between July 2009 and December 2011. Total biomass fluctuated seasonally, generally declining from spring to winter through the... -
Recovery dynamics of zooplankton following mouth-breaching in the temporarily open/closed Mdloti Estuary, South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: M Deale --- School of Life Sciences, South Africa R Perissinotto --- School of Life Sciences, South Africa NK Carrasco --- School of Life Sciences, South AfricaMouth-breaching events have major impacts on biological processes in temporarily open/closed estuaries. The aim of this investigation was to monitor zooplankton recovery dynamics following artificial breaching of the Mdloti Estuary in February 2004. Spatial and temporal patterns in zooplankton distribution... -
Effects of water quality changes on phytoplankton and lesser flamingo Phoeniconaias minor populations at Kamfers Dam, a saline wetland near Kimberley, South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: LM Hill --- School of Agricultural, Forest and Environmental Sciences, USA WW Bowerman --- University of Maryland, USA JC Roos --- Water Quality Consultants, South Africa WC Bridges --- Department of Mathematical Sciences, USA MD Anderson --- BirdLife South Africa, South AfricaKamfers Dam, a wetland near Kimberley, South Africa, supports a population of Near Threatened lesser flamingos Phoeniconaias minor. The cyanobacterium Arthrospira fusiformis (Voronikhin) Komarek and Lund 1990, the flamingos’ food source, was in bloom in April 2009. The city's wastewater... -
Detection of land cover changes around Lake Mutirikwi, Zimbabwe, based on traditional remote sensing image classification techniques
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: T Dube --- Discipline of Geography, School of Agricultural, Earth and Environmental Sciences, South Africa W Gumindoga --- Department of Civil Engineering, Zimbabwe M Chawira --- Zimbabwe Environmental Law Association, ZimbabweLand cover changes around Lake Mutirikwi in 1984–2011 were mapped from Landsat images using traditional image classification methods including the maximum likelihood classifier algorithm. The possibility of mapping the coverage and abundance of surface floating aquatic weeds was also tested... -
Spatial distribution of soluble reactive silica (SRSi) in the Tanzanian waters of Lake Victoria and its implications for diatom productivity
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: GW Ngupula --- Tanzania Fisheries Research Institute, Tanzania CN Ezekiel --- Tanzania Fisheries Research Institute, Tanzania ASE Mbonde --- Tanzania Fisheries Research Institute, Tanzania B Kashindye --- Tanzania Fisheries Research Institute, Tanzania E Mboni --- Tanzania Fisheries Research Institute, TanzaniaSoluble reactive silica (SRSi) concentrations and diatom abundance were determined during four surveys in the Tanzanian waters of Lake Victoria between 2005 and 2008. The SRSi concentrations increased towards offshore sites, while the opposite was true for diatom abundance. The... -
THE USE OF TROFIC AS AN AID FOR THE MANAGEMENT OF EUTROPHIC LAKES
Item type: Journal Article • Journal: Southern African Journal of Child and Adolescent Mental Health • Authors: K. Clarke --- , A.C. Jarvis --- , P.J. Ashton --- , T. Zohary --- ,As a result of eutrophication studies that have been performed by the National Institute for Water Research for many years it was decided in 1980 that a detailed investigation into this area take place. Hypertrophic Hartbeespoort Dam was selected as... -
FUTURE CHALLENGES IN WATER QUALITY MODELLING WITH PARTICULAR REFERENCE TO OPERATIONALLY CLOSED CATCHMENTS
Item type: Journal Article • Journal: Southern African Journal of Child and Adolescent Mental Health • Authors: S.F. Forster --- Department of Water Affairs, South Africa F.A. Stoffberg --- Department of Water Affairs, South Africa J.A. van Rooyen --- Department of Water Affairs, South AfricaAs a result of the declining quality of many water sources, the use of water quality models in planning is increasing. To date applications have involved the simulation of total dissolved salts and nutrients, largely in catchments affected by urban... -
Historical cyst record as evidence for the recent introduction of the dinoflagellate Gymnodinium catenatum in the north-eastern Atlantic
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: A Amorim B DaleThe geographical origin of the warm-temperate paralytic shellfish poison producer Gymnodinium catenatum Graham is still under debate. It was first reported in the north-eastern Atlantic in 1976, from the Galician rías (North-West Iberia). Since then, and until 1995, recurrent blooms... -
Temporal trends in total phosphorus, temperature, oxygen, chlorophyll a and phytoplankton populations in Hartbeespoort Dam and Roodeplaat Dam, South Africa, between 1980 and 2000
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: CarinE van Ginkel MichaelJ SilberbauerEutrophication, phytoplankton blooms and changes to the phytoplankton composition are some of the problems facing the managers of Hartbeespoort Dam and Roodeplaat Dam. Trends, both decreasing and increasing, are visible in the phosphorus concentrations, temperatures, dissolved oxygen concentrations and chlorophyll... -
Environmental impact of seasonal integrated aquaculture ponds ('fingerponds') in the wetlands of Lake Victoria, Kenya: an assessment, with the aid of Bayesian Networks
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Julius Kipkemboi AnneA van Dam Patrick DennyThe potential effect on ecosystem integrity of the use of natural wetlands for seasonal wetland fishponds ('fingerponds'), integrated with vegetable production for livelihood demands, was evaluated using experimental sites at Lake Victoria, Kenya. Soluble reactive phosphorous and total phosphorus, ammonium,... -
Lake Victoria water resources management challenges and prospects: a need for equitable and sustainable institutional and regulatory frameworks
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: GB LuiloCurrent issues relating to water utilisation, pollution and management in Lake Victoria, as well as legislative and regulatory history governing the management of the Lake Victoria Basin are reviewed. The articles of the agreements, many of which are now outdated,... -
Remediation of eutrophic water using Lemna minor in a controlled environment
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: AA Ansari FA KhanThe growth response of common duckweed Lemna minor was studied at various temperature and pH levels for its possible application for remediating eutrophic waters. The dry weight, chlorophyll a, nitrogen, phosphorus, potassium, peroxidase (POD), catalase (CAT) and malondialdehyde (MDA) levels... -
Composition and abundance of the zooplankton community in the Bitter Lakes, Egypt, in relation to environmental factors
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: RA El-BassatThe taxonomic composition of the zooplankton community of the Bitter Lakes, Egypt, was examined in 2003–2004 in relation to the spatial and temporal distribution of environmental factors. Copepoda were dominant, forming 49% of the zooplankton, followed by Protista at 37%... -
Responses of primary producers to mouth closure in the temporarily open/closed Great Brak Estuary in the warm-temperate region of South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: M Nunes --- Department of Botany, South Africa JB Adams --- Department of Botany, South AfricaLow river inflow conditions during 2009/2010 resulted in the mouth of the Great Brak Estuary remaining closed for almost two years. The low water level in Wolwedans Dam resulted in no annual environmental flow releases being made, causing mouth closure... -
Nile perch and the transformation of Lake Victoria
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: A Taabu-Munyaho --- National Fisheries Resources Research Institute (NaFIRRI), Uganda BE Marshall --- Lake Victoria Fisheries Organisation (LVFO), New Zealand T Tomasson --- United Nations University – Fisheries Training Programme (UNU–FTP), Marine Research Institute, Iceland G Marteinsdottir --- Institute of Biology, IcelandThe transformation of Lake Victoria that began in 1980 followed the population explosion of Nile perch Lates niloticus, causing the apparent extirpation of 500+ endemic haplochromine species and dramatic physico-chemical changes. Officially introduced in 1962–1963, but present earlier, the reasons... -
Subfossil diatoms from Hann Park pond, Dakar, Senegal: floristic inventory and palaeoenvironmental reconstruction
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: I Badiane --- Département de Géologie, Faculté des Sciences et Techniques, E Sow --- Département de Géologie, Faculté des Sciences et Techniques, CAK Fofana --- Département de Géologie, Faculté des Sciences et Techniques, C Aw --- Département de Géologie, Faculté des Sciences et Techniques,Diatoms in a 100 cm-long core from a pond in Hann Forest Park, western Senegal, were studied with the aim of reconstituting this interdune depression’s history, particularly the human influence, during the last century. Sixty-three species and varieties of diatoms... -
Harmful cyanobacteria and their cyanotoxins in Egyptian fresh waters – state of knowledge and research needs
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: ZA Mohamed --- Department of Botany and Microbiology, Faculty of Science, EgyptCyanobacterial blooms have increased in freshwater ecosystems worldwide in the last century, mostly resulting from eutrophication and climate change. These blooms represent serious threats to environmental and human health because of the production of harmful metabolites, called cyanotoxins. Like many... -
Use of diatom indices to categorise impacts on and recovery of a floodplain system in South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: R Musa --- Department of Zoology, South Africa R Greenfield --- Department of Zoology, South AfricaThe trophic status of the Ramsar-accredited Nyl River floodplain, which is stressed by sewage treatment effluents, and its ability to restore normal conditions, were assessed in 2014–2015 using diatoms as biological indicators. The Trophic Diatom Index, Specific Pollution Sensitivity Index... -
Triggers of phytoplankton bloom dynamics in permanently eutrophic waters of a South African estuary
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: DA Lemley --- Botany Department and the Institute for Coastal and Marine Research, South Africa JB Adams --- Botany Department and the Institute for Coastal and Marine Research, South Africa NA Strydom --- Zoology Department, South AfricaThe permanently eutrophic Sundays Estuary experiences recurrent harmful algal blooms (HABs) of Heterosigma akashiwo (Raphidophyceae). This study aimed to identify the environmental variables shaping phytoplankton community composition and succession patterns during a typical spring/summer harmful algal bloom (HAB) period. Monitoring... -
Health and chemical burdens of fish species from polluted and hyper-eutrophic freshwater ecosystems in South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: GM Wagenaar --- Department of Zoology, South Africa IEJ Barnhoorn --- Department of Zoology, South AfricaThree aquatic ecosystems in South Africa, the Hartbeespoort, Klipvoor and Bospoort Dams, are classified as hyper-eutrophic, because of high nutrient loads and chemical pollution. Water and two fish species, Clarias gariepinus and Cyprinus carpio, were collected from these dams to... -
Nutrient fluxes from sediments pose management challenges for the Knysna Estuary, South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: LRD Human --- South African Environmental Observation Network, Elwandle Coastal Node, South Africa R Weitz --- Department of Botany, Institute for Coastal and Marine Research, South Africa BR Allanson --- Knysna Basin Project, Department of Zoology and Entomology, South Africa JB Adams --- Department of Botany, Institute for Coastal and Marine Research, South AfricaThis study investigated seasonal dynamics of benthic nutrient fluxes using in situ benthic chambers deployed over a 24–hour period at the sediment water interface for four distinct regions of the Knysna Estuary. The sediment in the Upper Estuary, Lagoon and... -
Nutrient enrichment as a threat to the ecological resilience and health of South African microtidal estuaries
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: JB Adams --- DST/NRF Research Chair in Shallow Water Ecosystems, South Africa S Taljaard --- DST/NRF Research Chair in Shallow Water Ecosystems, South Africa L van Niekerk --- DST/NRF Research Chair in Shallow Water Ecosystems, South Africa DA Lemley --- DST/NRF Research Chair in Shallow Water Ecosystems, South AfricaNutrient pollution in South African estuaries is described using a Driver-Pressure-State-Impact-Response framework. The root cause (‘driver’) of deteriorating water quality is rapid population growth that leads to increasing inputs from wastewater treatment works (WWTWs), stormwater run-off and agricultural return flow... -
Green technology for bioremediation of the eutrophication phenomenon in aquatic ecosystems: a review
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Mostafa El-Sheekh --- , Egypt Mohamed M Abdel-Daim --- , Saudi Arabia Mohamed Okba --- , Egypt Samiha Gharib --- , Egypt Asgad Soliman --- , Egypt Hala El-Kassas --- , EgyptEutrophication is a serious phenomenon that leads to vigorous algal blooms that alters the structure of ecosystems. It is caused by non-point sources of nutrients; as nitrogen and phosphorus, and point sources as wastewater effluent. Distinctive algae groups are responsible... -
A comparison of the water quality and plankton diversity of the Okamini Stream to the freshwater systems within the New Calabar River catchment, Port Harcourt, Nigeria
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: BB Otene --- Rivers State University, Nigeria I Thornhill --- University of Manchester, United Kingdom J Amadi --- Rivers State University, NigeriaThe water quality and phytoplankton diversity of the Okamini Stream, Port Harcourt, Nigeria was studied between April and June 2018 at three stations. The data was used to assess the health of the system for supporting local communities. Compared to... -
Long-term study of the drought impact on the phytoplankton concentration and assemblages in two water supply reservoirs in Namibia
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Johannes Sirunda --- Namibia Water Corporation, Namibia Paul Oberholster --- University of the Free State, South Africa Gideon Wolfaardt --- Stellenbosch University, South Africa Christoff Truter --- Toronto Metropolitan University, Canada Sean van der Merwe --- University of the Free State, South AfricaRising temperatures and increased occurrences of droughts, brought on by climate change, are expected to affect reservoir water levels. We hypothesised that the decrease in reservoir volumes in dams with desert climates will favour the growth of phytoplankton biomass, measured... -
Using Digital Earth Africa to monitor chlorophyll-a concentration and detect harmful algal blooms in Suguti Bay, Lake Victoria, Tanzania
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: JE Gimode --- Ardhi University, Tanzania AD Msusa --- Ardhi University, Tanzania Z Ngereja --- Ardhi University, TanzaniaLake Victoria is a vital source of drinking water for millions, necessitating continuous monitoring of chlorophyll-a (Chl-a) concentrations to assess its trophic status and support sustainable water resource management. This study aimed to provide a scalable, cost-effective alternative to traditional...