Prof Cate Brown Pengarang Dr Nick Rivers-Moore Pengarang

Metal accumulation in two contiguous eutrophic peri-urban lakes, Chivero and Manyame, Zimbabwe B Utete1,4*, C Phiri2, SS Mlambo3, N Maringapasi3, N Muboko1, TB Fregene4 and B Kavhu5 1 Chinhoyi University of Technology, Department of Wildlife Ecology and Conservation, Chinhoyi, Zimbabwe 2 Chinhoyi University of Technology, Department of Freshwater and Fishery Science, Chinhoyi, Zimbabwe 3 Chinhoyi University of Technology, Department of Biotechnology Science, Chinhoyi, Zimbabwe 4 Department of Aquaculture and Fisheries Management, University of Ibadan, Oyo State, Nigeria 5 University of Zimbabwe, Department of Geography and Environmental Science, Mt Pleasant, Harare, Zimbabwe *Corresponding author, e-mail: mkaiyo@gmail.com ABSTRACT Concentrations of aluminium, cadmium, chromium, cobalt, copper, iron, lead, nickel and zinc were determined in surface water, benthic sediments, and the gills, liver and stomach muscle tissues of Oreochromis niloticus and Clarias gariepinus in peri-urban lakes Chivero and Manyame, Zimbabwe. Five sites were sampled in each lake once per month in November 2015, February, May, August and November 2016. Pollution load index detected no metal contamination, whereas the geo-accumulation index reflected heavy to extreme sediment pollution, with Fe, Cd, Zn, Cr, Ni and Cu present in both lakes. Significant spatial temporal variations were detected for Al, Cr, Cu and Pb across sites within and between the two lakes. High Fe, Al and Cr concentrations in water and sediments in lakes Chivero and Manyame derive from geogenic background sources in addition to anthropogenic loads and intensity. Elevated concentrations of Al, Pb, Cu, Cd, Fe and Zn detected in gills, liver and stomach tissue of catfish corroborate concentrations in water and sediments, and pose the highest ecological and health risk for hydrobionts in lakes Chivero and Manyame. Contiguity of peri-urban lakes exposes them to similar threats, necessitating creative water management strategies, which ensure ecological continuity. Keywords: bio-accumulation, ecological risk, hydrobionts, lentic systems, toxicodynamics Occurrence of oestrogenic pollutants and widespread feminisation of male tilapia in peri-urban dams in Bulawayo, Zimbabwe C Teta1*, BF Holbech2, L Norrgren3 and YS Naik4 1 Department of Environmental Science and Health, National University of Science and Technology, Bulawayo, Zimbabwe; Current address: Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa 2 Institute of Biology, University of Southern Denmark, Odense M, Denmark 3 Department of Pathology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden 4 Research and Innovation, National University of Science and Technology, Bulawayo, Zimbabwe * Corresponding author; e-mail: c.teta@ru.ac.za; tetacharlie@gmail.com ABSTRACT Peri-urban water bodies are at risk from excessive pollution as they are direct sinks for urban effluents. The occurrence of oestrogenic and androgenic endocrine disrupting chemicals (EdCs) in effluents and water bodies around the city of Bulawayo, Zimbabwe, and their effects on wild fish was investigated in 2013. Effluent and water were sampled from sewage treatment plants, an urban stream, and effluent-polluted dams, and were compared with a ‘pristine’ dam upstream of Bulawayo. Organic pollutants were extracted by solid-phase extraction and tested for EdCs using a yeast oestrogen/androgen screen. Oestrogenic and androgenic potencies were expressed as 17β-oestradiol equivalent (EEq) or dihydrotestosterone equivalent (TEq). Tilapia and catfish from the dams were analysed for gonado-somatic indices and testis histopathology. Effluents from STPs, which directly flow into Umguza dam, had EEq of 33 ng l−1 and 55 ng l−1, respectively. Umguza dam, Khami dam and Matsheumhlope Stream had EEqs of 237 ng l–1, 9 ng l−1 and 2 ng l−1, respectively. Androgenic activity was detected in only one STP (TEq = 93 ng l−1). Tilapia sampled from effluent-polluted dams had high incidences of testis-ova, but catfish had no signs of reproductive dysfunction. These findings underscore the need for greater attention to EdCs in developing countries where there is scant literature regarding their occurrence and impacts. Keywords: androgens, developing countries, endocrine disrupting chemicals, fish reproduction, oestrogens, urban effluent PAHs, OCPs and PCBs in sediments from three catchments in durban, South Africa T Vogt1* , R Pieters1 and BK Newman2,3 1 Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa 2 Coastal Systems Research Group, Council for Scientific and Industrial Research, Congella, Durban, South Africa 3 Nelson Mandela University, Port Elizabeth, South Africa *Corresponding author, email: tash.vogt@gmail.com ABSTRACT Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were analysed from sediment samples collected in 2012 from rivers, surface runoff canals and estuaries in three highly urbanised catchments in durban, KwaZulu-Natal, South Africa. PAHs were ubiquitous, at concentrations between 36–6 800 ng g−1 dry mass (dm). Congener ratio diagnosis suggests the PAHs were derived predominantly from pyrogenic sources. Four OCPs and/or their metabolites were detected at varying frequencies and concentrations. Of these, dichlorodiphenyltrichloroethane (ddT) and metabolites were most frequently detected and were at a high concentration in sediment in some systems. Toxaphene was detected at a high concentration at some sites. The total PCB concentration varied widely, from below the method detection limit to 110 ng g−1 (dm). Based on the comparison of chemical concentrations to international sediment quality guidelines, PAH, OCP and PCB concentrations in most sediment samples posed a low risk to sediment-dwelling organisms. However, in some instances the risk was moderate or high. It is recommended that these compounds be monitored more frequently and comprehensively in aquatic ecosystems to better understand the ecological and human health implications. Keywords: DDT, organic contaminants, sediment-dwelling organisms, sediment quality guidelines derivation of scenario-specific water quality guidelines for acid mine drainage in South Africa, using a risk-based approach EC Vellemu*, PK Mensah, N Griffin and ON Odume Unilever Centre for Environmental Water Quality, Institute for Water Research, Rhodes University, Grahamstown, Eastern Cape, South Africa *Corresponding author, email: evellemu@gmail.com ABSTRACT Acid mine drainage (AMd) continues to threaten water quality in many mining regions globally. data paucity renders it challenging to inform appropriate water quality management strategies for a succinct scientific understanding of the effects of AMd on freshwater ecosystems. The current study investigated the effects of Amd collected from a defunct coalmine in Mpumalanga, South Africa, on freshwater ecosystems using a risk-based approach on five indigenous species, Adenophlebia auriculata, Burnupia stenochorias, Caridina nilotica, Pseudokirchneriella subcapitata and Oreochromis mossambicus in 2016. Species responded differently to Amd after 96 hours and 240 hours of exposure in static experimental test designs. Burnupia stenochorias was more sensitive to AMd after 96 and 240 hours of exposure, whereas O. mossambicus was tolerant during short-term exposure, but became more sensitive after 240 hours of exposure than the other species tested. The availability of metals in AMd was directly associated with dilution rate. Scenario-specific water quality guidelines for AMd have been derived as 0.122% for short-term and 0.014% for long-term exposure. These may form important indicative dilutions for other AMds that do not match the scenarios of this study. The toxicity of AMd to a wide range of aquatic species, including field validations, requires further investigation. Keywords: ecosystems, mining, pollution, salinity, species sensitivity distribution Use of diatom indices to categorise impacts on and recovery of a floodplain system in South Africa R Musa and R Greenfield* Department of Zoology, University of Johannesburg, Auckland Park, South Africa. * Corresponding author: e-mail: rgreenfield@uj.ac.za ABSTRACT The 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 and the Generic diatom Index were used to characterise water quality under high and low flow conditions in 2014. An additional survey was conducted in May 2015, following an accidental sulphuric acid spill above the Sewage Treatment Works (STW). Significant linear correlations were identified between physico-chemical parameters and the indices, as well as between the three indices themselves, validating their use to infer water quality. Water quality deteriorated from the source of the Klein Nyl River, especially at the STW, but improved within the Nylsvley Nature Reserve wetland sampling site (NYL). Keywords: eutrophication, nutrients, pollution, Ramsar, sewage treatment, water quality, wetland Mesozooplankton of the Kosi Bay lakes, South Africa HL Jerling1* and SP Weerts1,2 1 Department of Zoology and Coastal Research Unit of Zululand, University of Zululand, Kwadlangezwa, 3886, South Africa 2 Coastal Systems Research Group, Natural Resources and the Environment, CSIR, Congella, 4013, South Africa *Corresponding author, e-mail: jerlingh@unizulu.ac.za ABSTRACT The Kosi coastal lake system, a chain of four interconnected basins, is located in the subtropical north-eastern corner of South Africa. Little information is available on zooplankton of the system and the main aim of this study is to report on zooplankton samples collected during 2002 and 2003. The set of samples consists of seasonal, subsurface mesozooplankton samples that were collected during nighttime in each of the lakes. A well-developed salinity gradient was evident along the interconnected lakes in the subsurface water during all seasons, ranging from freshwater in the upper lake Amanzamnyama to a maximum of 22 recorded in Lake Makhawulani. The zooplankton community structures of the lakes reflected the salinity gradient of the system, with some coastal marine taxa recorded in the lakes closer to the mouth and only freshwater taxa recorded in Lake Amanzamnyama. Mesozooplankton diversity and abundance were relatively low compared to other estuarine systems along the eastern coast of South Africa. The dominant taxa were calanoid copepods Acartiella natalensis and Pseudodiaptomus stuhlmanni and the mysid Mesopodopsis africana in the lower lakes, whereas cyclopoids Mesocyclops sp. and Thermocyclops sp. dominated the freshwater lake Amanzamnyama. Keywords: coastal lakes, estuaries, salinity, zooplankton Effect of temperature on seed production in the invasive grass Glyceria maxima (Hartm.) Holmb. (Poaceae) in South Africa LF Mugwedi1,2,3*, JM Goodall1,2, ETF Witkowski1 and MJ Byrne1,4 1 School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa 2 Agricultural Research Council, Plant Protection Research Institute, Hilton, South Africa 3 Current address: Institute of Natural Resources, 67 St Patricks Rd, Scottsville, South Africa 4 Centre of Excellence for Invasion Biology, University of the Witwatersrand, Johannesburg, South Africa * Corresponding author, e-mail: lutendo.mug@gmail.com ABSTRACT Temperature is one of the main factors that determine sexual reproduction in terrestrial and emergent aquatic plant species. The effect of temperature on sexual reproduction and seed production of Glyceria maxima (Hartm.) Holmb. in the southern hemisphere is unknown. Glyceria maxima collections in February 2010 at three isolated infestations in KwaZulu-Natal failed to yield a single seed, only empty panicles. Laboratory experiments showed that vernalisation had no consistent effect on seed production. Field- and laboratory-grown plants produced seeds in the 2010/2011 season, because of having sufficient time at optimum temperatures required for seed production (1 491 and 1 585 hours, respectively), compared to a shorter period (1 352 hours) of suitable temperatures during the 2009/2010 growing season. An inadequate period of optimum temperatures (15–25 °C) during seed production resulted in the lack of seeds in the field in the 2009/2010 growing season. This study showed that temperature and duration of exposure thereto during the seed-production period play vital roles in G. maxima sexual reproduction. Keywords: anthesis, panicle, perennial grass, seed development, seed set, vernalisation diet of bluegill Lepomis macrochirus in a South African reservoir during winter and summer PM Ndaleni1,2,3*, RJ Wasserman2,3,4, BR Ellender2,3 and OLF Weyl1,3,5 1 Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, 6140, South Africa 2 South African Institute for Aquatic Biodiversity, Grahamstown, 6140, South Africa 3 Centre for Invasion Biology, SAIAB, Grahamstown, 6140, South Africa 4 School of Science, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia 5 DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, SAIAB, Grahamstown, 6140, South Africa *Corresponding author, e-mail: ndalenipm@gmail.com ABSTRACT Alien fishes are considered a major threat to aquatic biodiversity in South Africa, yet relatively little regional information on their biology and ecology is available for many of these species. Seasonal changes in the diet of the bluegill Lepomis macrochirus in Howieson’s Poort dam, Grahamstown, were assessed during summer and winter in 2014–2015, using stomach content analysis. In winter, juvenile and adult fish diets were dominated by crustacean zooplankton and insects, respectively. In summer, juvenile fish fed on crustaceans and insects, whereas adults consumed mostly fish eggs, indicating a potential impact by these invasive fish on native fish through oophagy. Keywords: dietary shift, non-native fish, prey groups, stomach contents