Responses of selected biota after biostimulation of a vegetable oil spill in the Con Joubert Bird Sanctuary wetland: A pilot study

An investigation on the effect of a vegetable oil spill was conducted on the biological diversity of the Con Joubert Bird Sanctuary wetland in South Africa before and after biostimulation with different concentrations of fertilizer during 2008. Biostimulation responses were analyzed 30 days after different concentrations of fertilizer were applied to the freshwater wetland at three selected sampling sites. The Con Joubert Bird Sanctuary wetland showed a high degree of contamination after a vegetable oil spill, resulting in a large volume of vegetable oil in the sediment and water column, respectively. Vegetable oil contents differed at each sampling site before biostimulation and each site showed variable responses after biostimulation. In this study, biostimulation results displayed a high yield of microbial activity and vegetable oil degradation at site one and two respectively. However, the degradation of the high vegetable oil concentrations within the sediments at sampling site 3 may have been hampered or retarded by the polymerized state of the vegetable oil. The phytoplankton, protozoan, macroinvertebrates and microorganisms assemblage were affected and showed little improvement at site 3, even after biostimulation with the high fertilizer concentration of 800 g/m2, in comparison to sites 1 and 2 which showed greater biological activities and degradation of vegetable oil.Keywords: Biostimulation, vegetable oil spill, fresh water wetlandAfrican Journal of Biotechnology Vol. 12(4), pp. 385-39

Factors facilitating sustainable scientific partnerships between developed and developing countries

International scientific partnerships are key to the success of strategic investments in plant science research and the farm-level adoption of new varieties and technologies, as well as the coherence of agricultural policies across borders to address global challenges. Such partnerships result not only in a greater impact of published research enhancing the career development of early and later stage researchers, but they also ensure that advances in plant science and crop breeding technologies make a meaningful contribution to society by brokering acceptance of emerging solutions to the world problems. We discuss the evidence showing that despite a lack of funding, scientists in some African countries make a significant contribution to global science output. We consider the criteria for success in establishing long-term scientific partnerships between scientists in developing countries in Southern Africa (“the South”) and developed countries such as the UK (“the North”). We provide our own personal perspectives on the key attributes that lead to successful institutional collaborations and the establishment of sustainable networks of successful “North-South” scientific partnerships. In addition, we highlight some of the stumbling blocks which tend to hinder the sustainability of long-term “North-South” scientific networks. We use this personal knowledge and experiences to provide guidelines on how to establish and maintain successful long-term “North-South” scientific partnerships.National Research Foundation of South Africa, Winter Cereal Trust and African Union Research Grant Programme funded by the European Union.http://journals.sagepub.com/home/oaghj2021Forestry and Agricultural Biotechnology Institute (FABI)Plant Production and Soil Scienc

Chemical characteristics and limnology of Loskop Dam on the Olifants River (South Africa), in light of recent fish and crocodile mortalities

A declining crocodile population and fish mortalities attributed to pansteatitis, along with increasing blooms of Microcystis aeruginosa and Ceratium hirundinella, have led to serious concerns about water quality in Loskop Dam, on the Olifants River, South Africa. Major impacts include acid mine drainage and eutrophication associated with sewage effluent. However, the specific causes of pansteatitis remain elusive. In 2011 the water chemistry and limnology of Loskop Dam were studied to determine factors that may be influencing aquatic ecosystem health. Long-term monitoring data collected by the Department of Water Affairs were analysed for trends using a seasonal Mann-Kendall trend test, and were used to determine the trophic state of Loskop Dam using the Carlson index. Multiple sites were sampled which showed the reservoir was heterogeneous with regard to nutrient concentrations, algal biomass and dissolved metals. Specifically, the transitional zone was characterised by frequent algal blooms, resulting in fluctuating dissolved oxygen (range = 2.1–14.5 mg/ℓ) and pH (range = 7.35–10.59) levels. Using total phosphorus, Secchi depth, and chlorophyll-a concentrations, the trophic state of Loskop Dam was classified as meso- to eutrophic. Significant positive trends were observed in total (Tau = 0.422) and dissolved inorganic (Tau = 0.193) phosphorus.The reservoir showed a monomictic pattern of summer stratification (October to April) and holomictic winter circulation (June to July), with an increase in the depth and extent of anoxia in the hypolimnion when compared to previous research. Simultaneous elevated concentrations of manganese (>370 μg/ℓ) and iron in near-bottom water samples coincided with hypolimnetic anoxia. Aluminium concentrations exceeded the target water quality range (>10 μg/ℓ) during summer (December) in both surface and near-bottom water samples. We conclude that fish in Loskop Dam are periodically exposed to several physiological stressors including elevated ammonia, aluminium, iron and manganese and possibly hydrogen sulphide, as well as low dissolved oxygen. While these factors have never individually been linked to pansteatitis, their combined impacts have not been studied. To ensure the sustainability of Loskop Dam, catchment management plans must focus on reducing phosphorus inputs, and continue seeking treatment solutions for mine-water associated with abandoned and working coal mines.http://www.wrc.org.zaam2014mn201

Phytoplankton yield changes after enrichment in microcosm experiments: applications for predicting progressive eutrophication in a mesotrophic lake, South Africa

Established microcosms containing surface water from the mesotrophic Lake Mokolo were subjected to enrichment of different concentrations with phosphorus. The microcosms were sampled through a 20 day succession period to determine the net effects of increased concentrations of phosphorus in the water column on the phytoplankton community structure during the winter and summer seasons. A significant increase in chlorophyll a (chl-a) was observed when treatments of 30, 40 and 60 μg L-1 P were compared to the controls. On day zero in both the winter and summer microcosm experiments, all four phosphorus treatments had similar species diversity of phytoplankton of the specific seasoned tested (winter: Margalef index = 223; summer: Margalef index = 347). However, 13 days after the addition of 40 and 60 μg L-1 P, the phytoplankton community exhibited a strikingly different species richness (winter: Margalef index = 123; summer: Margalef index = 114). In the winter microcosm experiments, the green alga Scenedesmus armatus dominated the phytoplankton composition at enrichment levels of 40 and 60 μg L-1 P up to day 20. The biovolume of the dinophyceae Ceratium hirundinella declined rapidly after the addition of 40 μg L-1 P in the different summer microcosms. In the summer microcosms, Spondylosium secedens and Microcystis aeruginosa dominated the 40 and 60 μg L-1 P microcosm enrichment experiments.http://www.academicjournals.org/AJBam2013mn201

Microcystin-LR equivalent concentrations in fish tissue during a postbloom Microcystis exposure in Loskop Dam, South Africa

The effects of a decomposing cyanobacteria bloom on water quality and the accumulation of microcystin-LR equivalent toxin in fish at Loskop Dam were studied in May 2012. Enzyme-linked immunosorbent assay [ELISA] was used to confirm the presence of microcystin-LR equivalent in the water and to determine the microcystin (MCYST) concentration in the liver and muscle of fish. The lowest concentration of extracellular MCYST-LR equivalent was recorded in the lacustrine zone, where no cyanobacterial cells were observed, while the highest concentration (3.25 μg l−1), 3.25 higher than World Health Organization standard, was observed in the riverine zone. Extremely high MCYST-LR equivalent concentrations of 1.72 μg MCYST-LReq kg−1 in the liver and 0.19 μg kg−1 in muscles of Labeo rosae, and 2.14 μg MCYST-LReq kg−1 in the liver and 0.17 μg kg−1 in muscles of Oreochromis mossambicus, indicate that the consumption of sufficient fish biomass might cause severe adverse effects in humans. Microscopic analyses of the stomach content of both fish species revealed low numbers of cyanobacterial Microcystis aeruginosa cells in comparison to other phytoplankton. The extracellular MCYST-LR equivalent of the decomposing bloom may have played a major role in the high levels observed in the livers of the two fish species. These findings are important for all downstream water users.The National Research Foundation (NRF; TTK2006062100013); Council for Scientific and Industrial Research; Department of Genetics, University of Stellenbosch; and the Department of Biodiversity, University of Limpopo as well as the Belgian Vlaamse Interuniversitaire Raad University Development Cooperation funding programme.http://www.tandfonline.com/loi/taas20hb2016Paraclinical Science

Assessment of the effect of nanomaterials on sediment-dwelling invertebrate Chironomus tentans larvae

Studies were conducted to determine the effects of a panel of seven nanomaterials (NMs), namely: a-alumina, g-alumina, precipitated silica; silica fume, calcined silica fume, colloidal antimony pentoxide (Sb2O5), and superfine amorphous ferric oxide (Fe2O3), on sediment dwelling invertebrates Chironomus tentans under controlled laboratory conditions. Percentage survival, enzyme activities, growth development, and DNA fragmentation parameters were studied as acute, biochemical, and physiological toxicities of NMs, respectively. Quantitation of catalase and peroxidase enzyme activity demonstrated that toxicant stress of the NMs increased enzyme activity in a concentration dependent fashion across all treatments. The percentage growth length of the test specimens exposed to different NMs was significantly reduced compared to the negative control while only five concentrations were not in the toxic range, namely; Fe2O3 (5 mg/kg); silica fume (5 mg/kg, 50 mg/kg); Sb2O5 (5 mg/kg) and calcined silica fume (5 mg/kg). Genotoxic stress assessed by use of DNA laddering showed complementary findings to the other ecotoxicological endpoints tested in this study—the percentage survival and growth length inhibition.The Parliamentary Grant funding support (No. JNPPG03) from the CSIR (NM, PJO, PJA) as well as the research funding from the University of Pretoria (WWF), University of Limpopo (PKC), University of Stellenbosch (AMB) are acknowledged.http://www.elsevier.com/locate/ecoenvhb2016Chemical EngineeringParaclinical Science

Health risk implications from simultaneous exposure to multiple environmental contaminants

Water quality has deteriorated in the upper Olifants River system, South Africa, as a result of land use activities which include mining, agriculture and industries. A health risk assessment was conducted from 2009 to 2011 in the catchment to determine the possible risks local communities face from various pollutants such as microbials, heavy metals and oestrogen in the river water and vegetation. Aluminium and manganese accumulated in plants and vanadium and aluminium concentrations found in selective water samples posed significant health risks when consumed. A quantitative microbial risk assessment revealed that the combined risk of infection ranged from 1 to 26 percent with the Norovirus posing the overall greatest health risk. The anticipated disability adjusted life years resulting from drinking untreated water from these sites are in the order of 10,000 times greater than what is considered acceptable. The oestradiol activity, caused by endocrine disrupting compounds in the water, measured above the trigger value of 0.7 ng L−1. Impoverished communities in the area, who partially depend on river water for potable and domestic use, are exposed to immune-compromising metals that increase their probability of infection from waterborne diseases caused by the excess microbial pathogens in the contaminated surface water.Olifants River Forumhttp://www.elsevier.com/locate/ecoenvhb201

Linking hydro-morphology with invertebrate ecology in diverse morphological units of a large river-floodplain system

Interdisciplinary research in the fields of ecohydrology and ecogeomorphology is becoming increasingly important as a way to understand how biological and physical processes interact with each other in river systems. The objectives of the current study were 1) to determine changes in invertebrate community due to hydrological stages, 2) to link local physical features [flow configuration, sediment composition and morphological feature) with the ecological structure between and within dissimilar morphological units (meander and confluence), and 3) to determine the existence and the origin of bed hydro-geomorphic patches, determining their ecological structure. Results were discussed in the frame of prevailing ecological models and concepts. The study site extends over a floodplain area of the large Paraná River (Argentina), including minor and major secondary channels as well as the main channel. Overall results suggested that hydrodynamics was the driving force determining distribution patterns of benthic assemblages in the floodplain. However, while the invertebrates living in minor secondary channels seem to benefit from flooding, this hydrological phase had the opposite effect on organisms from the main and major secondary channels. We also found a clear linkage between physical features and invertebrate ecology, which caused a dissimilar fauna structure between and within the meander and the confluence. Furthermore, several sandy-patches were recorded in the confluence. These patches were colonized by the particular benthic assemblage recorded in the main channel, supported the view of rivers as patchy discontinua, under uncertain ecological equilibrium.Instituto de Limnología "Dr. Raúl A. Ringuelet

The influence of a toxic cyanobacterial bloom and water hydrology on algal populations and macro-invertebrate abundance in the upper littoral zone of Lake Krugersdrift, South Africa

The biological interactions and the physical and chemical properties of the littoral zone of Lake Krugersdrift were studied for a 4-month period when a dense, toxic cyanobacterial bloom dominated by Microcystis aeruginosa was present in the main lake basin. The presence of a toxic strain of M. aeruginosa was confirmed through the use of ELISA and molecular markers that detect the presence of the mcyB and mcyD genes of the mcy gene cluster that synthesizes microcystin. An increase in Microcystis toxicity at sites dominated by the cyanobacterial scum was accompanied by an increase in total abundance of the macroinvertebrate families Hirudinae, Chironomidae, and Tubificidae. Sites located away from the cyanobacterial scum had a lower abundance but a higher diversity of macroinvertebrates. The water quality under the Microcystis scum was characterized by low pH values, low concentrations of dissolved oxygen, and lower total alkalinity values. The periphytic alga Ulothrix zonata was absent in areas dominated by the cyanobacterial scum, possibly as a result of overshadowing by the scum or direct toxic allelopathic effects on growth and photosynthesis. The diatom Diatoma vulgare dominated the benthic algal flora beneath the cyanobacterial scum