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THE EFFECT OF TEMPERATURE ON SPECIFIC GROWTH RATE AND ACTIVATION ENERGY OF MICROCYSTIS AND SYNECHOCOCCUS ISOLATES RELEVANT TO THE ONSET OF NATURAL BLOOMS
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: G. H.J. Krüger --- Department of Botany, South Africa J.N. Eloff --- Department of Botany, South AfricaTo investigate the correlation between temperature and the appearance of Microcystis blooms in nature, the effect of temperature on the growth of four Microcystis izolates (two toxic and two non-toxic) was investigated. The lower temperature limit for Microcystis varied between... -
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... -
Alexandrium catenella and Alexandrium tamarense in the North Lake of Tunis: bloom characteristics and the occurrence of paralytic shellfish toxin
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Z Armi --- , Tunisie A Milandri --- , Italie S Turki --- , Tunisie B Hajjem --- , TunisieThe dinoflagellate Alexandrium is thought to be the main species responsible for paralytic shellfish poisoning (PSP) throughout the world. The genus Alexandrium is present in unusually high diversity in the North Lake of Tunis, a productive Mediterranean fishing and shellfish... -
Algae, phytoplankton and eutrophication research and management in South Africa: past, present and future
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: CE van Ginkel --- , South AfricaA brief history of South African research on and management of algae-, phytoplankton- and eutrophication-related problems is presented, including their ecological, social and economic impacts, which provides a basis for formulation of future research needs. The contributions of southern African... -
Algal blooms in Nigerian waters: an overview
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: GA Akin-Oriola MA Anetekhai A OriolaAwareness of harmful algal blooms (HABs) and their associated impacts is poor or lacking in the West African sub-region. Different aquatic environments in Nigeria have reportedly experienced blooms of algae either seasonally or year round, but there are no documented... -
The use of fuzzy logic for data analysis and modelling of European harmful algal blooms: results of the HABES project
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: AN Blauw P Anderson M Estrada M Johansen J Laanemets L Peperzak D Purdie R Raine E VahteraFuzzy logic was applied to model blooms of Nodularia spumigena, Dinophysis spp., Alexandrium minutum, Karenia mikimotoi and Phaeocystis globosa at various European sites as part of the Harmful Algal Blooms Expert System (HABES) project. This modelling approach was useful in... -
Examining the 'global spreading hypothesis' using graph theory
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: F Jordán T WyattA persistent view, called the 'global spreading hypothesis', maintains that the frequency, magnitude and geographical extent of harmful algal blooms have increased in recent decades. These putative trends have been variously attributed to nutrient enrichment, climate change and inadequate databases... -
Evaluation of California isolates of Lingulodinium polyedrum for the production of yessotoxin
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: M Armstrong R KudelaYessotoxin (YTX) is a newly discovered type of phycotoxin that is commonly produced by two dinoflagellates, Protoceratium reticulatum and Lingulodinium polyedrum. P. reticulatum has been confirmed to produce YTX and other analogues from isolates in New Zealand, Norway, Spain, Italy,... -
HAB outreach using multimedia: integrating ocean research and education
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: A deCharon S Etheridge T McDonnell Wysor M SierackiThis paper highlights a few of the education and outreach products on harmful algal blooms (HABs) that have been developed at Bigelow Laboratory for Ocean Sciences, a non-profit organisation dedicated to marine biological research and education. The 'Toxic & Harmful... -
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... -
Cylindrospermopsis raciborskii, a toxic invasive cyanobacterium in South African fresh waters
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Sanet Janse van Vuuren GP KrielCylindrospermopsis raciborskii, a problem-causing cyanobacterium capable of releasing potent toxins, has become increasingly prevalent in South African freshwaters, especially in the lower reaches of the Orange River. This organism was first detected during the summer (January to March) of 2000... -
Variations in the dominant algal bloom-forming species in the western South China Sea from 1993 to 2007
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: CL Liu --- Key Laboratory of Tropical Marine Environmental Dynamics, and Key Laboratory of Marine Bio-resources Sustainable Utilization, China DL Tang --- Key Laboratory of Tropical Marine Environmental Dynamics, and Key Laboratory of Marine Bio-resources Sustainable Utilization, China SF Wang --- Key Laboratory of Tropical Marine Environmental Dynamics, and Key Laboratory of Marine Bio-resources Sustainable Utilization, China L Nguyen-Ngoc --- , VietnamThe study investigated the spatial and temporal variations of harmful algal bloom (HAB) species in the western South China Sea (SCS) for the period 1993-2007, using in situ HAB and remotely sensed datasets. A significant change in the dominant bloom... -
Changes in density and composition of algal assemblages in certain unit processes of two South African water purification plants
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: MGJ Oosthuizen --- Unit for Environmental Sciences and Management, South Africa S Janse van Vuuren --- Unit for Environmental Sciences and Management, South AfricaThe water purification plants at Virginia and Bothaville, South Africa, experience problems with cyanobacteria and other algae. Their algal assemblages were studied during 2010 and 2011 to determine the dominant species that may pose problems in purification. Cyanobacteria, diatoms and... -
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... -
Seasonal and sub-seasonal oxygen and nutrient fluctuations in an embayment of an eastern boundary upwelling system: St Helena Bay
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: GC Pitcher --- Fisheries Management Branch, Department of Agriculture, Forestry and Fisheries, South Africa TA Probyn --- Fisheries Management Branch, Department of Agriculture, Forestry and Fisheries, South AfricaSeasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the... -
Eutrophication of Ethiopian water bodies: a serious threat to water quality, biodiversity and public health
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: T Fetahi --- Aquatic Ecology, EthiopiaFreshwater ecosystems provide several ecological and economic services. However, these ecosystems in Ethiopia are deteriorating, because of economic growth, unwise use and pollution (eutrophication). This paper reviews existing trends of eutrophication in Ethiopian water bodies, identifies principal sources of nutrient... -
Physico-chemical and microalgal gradients change rapidly in response to mouth closure in a predominantly open 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 AfricaA third of South Africa’s freshwater flow no longer reaches the coast, yet few systems have shifted from being permanently open to temporarily closed. For the first time since 1969, the Gamtoos Estuary mouth closed in June 2018, because of... -
Knysna Estuary health: ecological status, threats and options for the future
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: L Claassens --- Department of Zoology and Entomology, South Africa RSK Barnes --- Department of Zoology and Entomology, South Africa J Wasserman --- Department of Botany, DST/NRF Research Chair in Shallow Water Ecosystems, South Africa SJ Lamberth --- Fisheries Research and Development, Department of Environment, Forestry and Fisheries, South Africa NAF Miranda --- Department of Botany and Zoology, South Africa L van Niekerk --- Council for Scientific and Industrial Research, South Africa JB Adams --- Department of Botany, DST/NRF Research Chair in Shallow Water Ecosystems, South AfricaThe Knysna Estuary is South Africa's most important estuary in terms of conservation, containing an estimated 42% of all estuarine biodiversity. Despite formal protection the estuary is open access and vulnerable to resource exploitation, development, pollution and freshwater inflow alterations... -
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... -
Mass developments of Euglena sanguinea Ehrenberg in South Africa
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: S Janse van Vuuren --- , South Africa A Levanets --- , South AfricaBlooms of Euglena sanguinea Ehrenberg were observed at two different locations in South Africa, Mpumalanga province during 2016 and Limpopo province during 2020. Besides being responsible for a blood-red discolouration of the water, the species is also toxic, causing fish... -
The influence of estuary eutrophication on the benthic diatom community: a molecular approach
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: M Nunes --- , South Africa DA Lemley --- , South Africa GF Matcher --- , South Africa JB Adams --- , South AfricaThe occurrence of harmful algal blooms (HABs) is increasing in frequency and intensity in South African estuaries because of eutrophication. This study used DNA metabarcoding to identify the benthic diatom community structure in the eutrophic Sundays Estuary. The recurrent HAB... -
The distribution of dinoflagellate cyst assemblages in recent sediments of the Oualidia Lagoon, Morocco, with a focus on toxic species
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: K Chaira --- , Morocco H Rhinane --- , Morocco B Ennaffah --- , Morocco S Maimouni --- , Morocco R Sagou --- , Morocco S Loulad --- , Morocco A BenMhamed --- , Morocco A Agouzouk --- , Morocco S BenBrahim --- , Morocco E Masseret --- , France M Laabir --- , FranceHarmful algal blooms (HABs) are becoming widely distributed and more frequent, threatening socioecosystems and human health. We determined species composition, abundance and spatial distribution of dinoflagellate cysts in the upper sediment of the Oualidia Lagoon located on the Atlantic coast... -
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... -
Rapid spread of Euglena sanguinea Ehrenberg (Phylum Euglenophyta) in South African freshwater bodies: A potential threat
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: Sanet Janse van Vuuren --- North-West University, South Africa Anatoliy Levanets --- North-West University, South Africa Daniël Erasmus --- North-West University, South AfricaEuglena sanguinea is a red-pigmented euglenid species known for producing the ichthyotoxin euglenophycin, which has been associated with fish mortalities in various freshwater systems. First reported in South Africa from the Kruger National Park in 2016, E. sanguinea has since...