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EARLY OBSERVATIONS ON SOME LIMNOLOGICAL CHARACTERISTICS OF THREE ORANGE FREE STATE IMPOUNDMENTS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: J.U. Grobbelaar --- , South AfricaThe first limnological investigations on three impoundments in the Orange Free State are described. No thermal stratification was found and water temperatures below 8,6°C were not measured. The waters were turbid and the unfavourable underwater light climate was the major... -
WATER TRANSPARENCY CHARACTERISTICS OF SOUTH AFRICAN IMPOUNDMENTS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Walmsley --- , South Africa C.A. Bruwer --- , South AfricaSome water transparency characteristics (Secchi disc transparency, mean diffuse light attenuation coefficient and turbidity) of a number of South African impoundments are compared. In general most impoundments may be considered to be highly turbid; for 92 impoundments considered in this... -
OBSERVATTVNS ON THE UNDERWATER LIGHT FIELD OF TWO HWERTROPHIC, SOUTH AFRICAN IMPOUNDMENTS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Robarts --- , South Africa T. Zohary --- , South Africa F. Ojeda --- , Chile C. C.E. Lovengreen --- , Chile R.D. Walmsley --- ,The spectral composition of the underwater light field was examined in two hypertrophic South African Impoundments (Hartbeespoort and Roodeplaat Dams) under a range of inorganic turbidities and chlorophyll α concentrations. The data indicated that inorganic turbidity and gilvin were dominant... -
AGE AND GROWTH OF LABEO UMBRATUS (PISCES: CYPRINIDAE) IN LAKE LE ROUX ON THE ORANGE RIVER, SOUTH AFRICA
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: GlennS. Merron --- , South Africa Tumi Tómasson --- , South AfricaAge, growth and relative body condition of Labeo umbratus in Lake le Roux were investigated from samples collected from 1979 to 1982. Annuli are formed once a year on the scales and otoliths as growth commences in spring or early... -
OBSERVATIONS ON THE UNDERWATER LIGHT FIELD OF TWO HYPERTROPHIC SOUTH AFRICAN IMPOUNDMENTS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: R.D. Robarts --- National Institute for Water Research, South Africa T. Zohary --- National Institute for Water Research, South Africa F. Ojeda --- Institute of Physics, Chile C. C.E. Lovengreen --- Institute of Physics, Chile R.D. Walmsley --- Foundation for Research and Development,The spectral composition of the underwater light field was examined in two hypertrophic South African impoundments (Hartbeespoort and Roodeplaat Dams) under a range of inorganic turbidities and chlorophyll a concentrations. The data indicated that inorganic turbidity and gilvin were dominant... -
TURBIDITY AND OTHER PHYSICAL FACTORS IN NATAL ESTUARINE SYSTEMS PART 1: SELECTED ESTUARIES
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: D.P. Cyrus --- Department of Zoology, South AfricaData on turbidity and the factors influencing it, such as wind and substratum, were collected from eight representative estuaries along the Natal Coast. The results showed that Natal Estuaries can be divided into one of four groups, according to the... -
TURBIDITY AND OTHER PHYSICAL FACTORS IN NATAL ESTUARINE SYSTEMS PART 2: ESTUARINE LAKES
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: D.P. Cyrus --- Department of Zoology, South AfricaData on turbidity, temperature and salinity and the factors which affect them, such as wind and substratum, were collected from Natal's two estuarine Lakes. The effects of wind and substratum, were collected from Natal's two estuarine Lakes. The effects of... -
Covariance Analysis of Chlorophyll Distribution in the Sundays River Estuary, Eastern Cape
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: T. Hilmer --- Department of Botany, South Africa G.C. Bate --- Department of Botany, South AfricaAn analysis of covariance performed on chlorophyll a distribution data from the Sundays River estuary identified five persistent water masses with significantly different chlorophyll a contents. These corresponded to different hydrodynamic regions within the estuary. The relationship between salinity and... -
TURBIDITY GRADIENTS IN TWO INDO-PACIFIC ESTUARIES AND THEIR INFLUENCE ON FISH DISTRIBUTION
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: D.P. Cyrus --- Coastal Research Unit of Zululand, Department of Zoology, South AfricaResearch undertaken in two widely separated estuaries in the Indo-Pacific, showed that both have distinct turbidity gradients. In the turbid St Lucia System, on the South East Coast of Africa (range 2 to 568 Nephelometric Turbidity Units (NTU)), different turbidity... -
COMPOSITION, ABUNDANCE AND SEASONALITY OF LARVAL FISH IN RICHARDS BAY HARBOUR, KWAZULU-NATAL, SOUTH AFRICA
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: S. A. Harris --- , , South Africa D. P. Cyrus --- , , South AfricaThe present study examined the composition, abundance and seasonality of fish larvae occurring in Richards Bay Harbour, over an 18-month period from June 1991 to November 1992. Ichthyoplankton samples were collected every six weeks at top, mid and bottom depths... -
Effects of the 2000 southern Mozambique floods on a marginal coral community: the case at Xai-Xai
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: MarcosAM Pereira Paulo MiguelB GonçalvesIn early 2000 the southern part of Mozambique suffered the worst flooding in 50 years, causing fatalities and considerable material loss. This study aimed to investigate the impact of this flood on the coral communities in Xai-Xai lagoon. Benthic cover... -
Fish assemblages in the Mfolozi–Msunduzi estuarine system, KwaZulu-Natal, South Africa, when not linked to the St Lucia mouth
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: L Vivier --- Coastal Research Unit of Zululand, Department of Zoology, South Africa DP Cyrus --- Coastal Research Unit of Zululand, Department of Zoology, South Africa RK Owen --- Coastal Research Unit of Zululand, Department of Zoology, South Africa HL Jerling --- Coastal Research Unit of Zululand, Department of Zoology, South AfricaThe fish community of the Mfolozi–Msunduzi estuarine system was investigated with particular emphasis on its role as a nursery area for marine fish when the adjacent St Lucia mouth is closed. The mouth was open during March 2007 and 2008... -
Physical and chemical characteristics of the Tanzanian inshore and offshore waters of Lake Victoria in 2005–2008
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: GW Ngupula --- , Tanzania CN Ezekiel --- , Tanzania IA Kimirei --- , Tanzania E Mboni --- , Tanzania BB Kashindye --- , TanzaniaAssuming that the inshore and offshore waters of Lake Victoria are impacted differently by human activities in its catchment, this study investigated the water quality dynamics of the lake. A total of 29 stations were sampled in 2005–2008 for dissolved... -
Spatio-temporal variability of surface water quality parameters in a South African estuarine lake system
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: IA Russell --- , South AfricaLong-term (20+ years) water quality datasets for estuaries are rare, especially for smaller systems. Monitoring of salinity, temperature, pH, dissolved oxygen and turbidity has been undertaken since 1991 in the intensively utilised, modified, and managed temporarily open/closed Touw Estuary and... -
Seasonal variability of secondary production of cladocerans and rotifers, and their trophic role in Lake Tana, Ethiopia, a large, turbid, tropical highland lake
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: A Wondie --- Department of Fisheries, Wetlands and Wildlife, Faculty of Agriculture and Environment, Ethiopia S Mengistou --- Department of Zoological Sciences, EthiopiaDaily and annual production rates of eight cladoceran and two rotifer species, and their seasonal variation and trophic role in the large, turbid, tropical Lake Tana, Ethiopia, were assessed in 2003–2005. Laboratory cultures were used to infer cladoceran development times,... -
Spatio-temporal variability of five surface water quality parameters in the Swartvlei estuarine lake system, South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: IA Russell --- South African National Parks, South AfricaVariability of salinity, temperature, pH, dissolved oxygen and turbidity in the temporarily open/closed Swartvlei estuarine system, measured from 1991 to 2013, was investigated at various temporal (seasonal, estuarine open/closed phase, long-term) and spatial (inter- and intra-waterbody) scales. Longitudinal pH and... -
Influence of local environmental conditions and bleaching histories on the diversity and distribution of Symbiodinium in reef-building corals in Tanzania
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: LJ Chauka --- Institute of Marine Sciences, Tanzania G Steinert --- Institute for Chemistry and Biology of the Marine Environment (ICBM), Germany MSP Mtolera --- Institute of Marine Sciences, TanzaniaPollution, turbidity and coral bleaching history, as well as coral diversity, vary along the Tanzanian coastline. Prior to this study, it was not known whether exposure to such environmental variation might have influenced the diversity and distribution of Symbiodinium along... -
Suspended silt and salinity tolerances of the first zoeal stage of the fiddler crab Uca annulipes (Decapoda: Brachyura) and why marine connectivity is essential to the survival of the species
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: N Peer --- DST/NRF Research Chair in Shallow Water Ecosystems, South Africa NAF Miranda --- DST/NRF Research Chair in Shallow Water Ecosystems, South Africa R Perissinotto --- DST/NRF Research Chair in Shallow Water Ecosystems, South AfricaFiddler crabs (Uca spp.) undergo the zoeal stage of development in open-ocean waters, where they experience stable salinity levels, low turbidity and reduced predation. The St Lucia estuarine system has undergone many geomorphological changes, both natural and anthropogenic, and the... -
The application of Bayesian networks to evaluate risks from multiple stressors to water quality of freshwater ecosystems
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: V Wepener --- , South Africa GC O’Brien --- , South AfricaIt is difficult to predict and manage the ecological consequences of multiple water quality stressors on our freshwater systems. This is due to the dynamism of the source-stressor-response relationships and multiple factors including lack of data, complex impact pathways and...