Treated Acid Mine Drainage and Stream Recovery: Downstream Impacts on Benthic Macroinvertebrate Communities in Relation to Multispecies Toxicity Bioassays

Research ArticleThe success and long term effectiveness of extensive and expensive engineering solutions to restore streams impacted by Acid Mine Drainage (AMD) is rarely tested. Concentrations of pollutants were measured in water along a longitudinal gradient from a stretch of the Tweelopie stream, South Africa, that receives pH-treated acid mine drainage (AMD) from an abandoned gold mine. The biotoxic effects of treated AMD were determined through macroinvertebrate biotic indices (SASS5) and a battery of toxicity bioassays. These included the L. sativa, A. cepa, D. magna toxicity and Ames mutagenicity tests, as well as an in vitro human liver cancer cell line HepG2. Even though the Tweelopie stream was moderately to severely degraded by multiple anthropogenic stressors, the impact of the treated AMD was masked by the improvement in the system downstream after mixing with the domestic wastewater effluent receiving stream, and subsequent further dilution as a result of the karst springs downstream. The general improvement of the system downstream was clearly shown by the decrease in the ecotoxicity and mutagenicity in relation to the in-stream macroinvertebrates. PCA multivariate analysis successfully displayed associations between the different environmental variables and the decrease in toxicity and subsequent ecosystem improvement downstream. This study indicated that environmental management of AMD remediation should consider long term assessment strategies, including multiple factors, to promote biological ecosystem recovery

Dynamics of phytoplankton and phytobenthos in Lake Loskop (South Africa) and downstream irrigation canals

ArticleThe relationships between water quality and the phytoplankton community within Lake Loskop and irrigation canals downstream were studied over a period of one year from April 2009 to March 2010. The phytoplankton assemblage in Lake Loskop during this sampling period was dominated by the phytoplankton Ceratium hirundinella, with the highest biovolume of 12.1 mm 3 l- 1 recorded in late summer during January 2010. From the data generated the algae assemblage showed a clear trend in the two canals during the study period and also among sampling stations. The filamentous macroalgae Cladophora glomerata dominated the phytobenthos of the two irrigation canals during the whole sampling period. However, much higher biovolumes (8.5; 6.3 mm 3 l- 1) of Cladophora glomerata and total phosphates were observed in the long and short irrigation canals during lake overturn in the months of March and September, while much lower average biovolumes (2.4; 1.5 mm 3 l- 1) were recorded during the summer months. The dominance of the water column phytoplankton assemblage in the two irrigation canals by Ceratium hirundinella, Fragilaria crotonesis, Closterium stellenboschense and Closterium polystictum during autumn and spring was related to the observed lake overturn. Withdrawal of irrigation water from the upperhypolimnia during these two time periods transported phytoplankton species usually occurring in the epilimnion zone of Lake Loskop into the irrigation canals. This phenomonen resulted in these species becoming dominant during autumn in the water column of the two irrigation canals downstream of Lake Loskop. The phytoplankton assemblage data generated from this study can be used for management and control of nuisance macroalgae like Cladophora glomerata in irrigation canals. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany

Development of a rapid and sensitive battery of bioassays for risk assessment of cyanobacterial microcystin-LR in drinking water of rural water treatment plants, South Africa

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First report on the colony-forming freshwater ciliate Ophrydium versatile in an African river

Ophrydium versatile (Muller 1786) Ehrenberg 1830 - a symbiotic ciliate that forms gelatinous colonies - is widely distributed in temperate lakes in Europe and America, but has not previously been recorded from rivers. In this paper we report the first record of O. versatile in an African river, based on an identity confirmed by molecular taxonomic identification. The limnological conditions within the Lephalala River during the sampling period were characterised as oligotrophic with low DOC concentrations, similar to the conditions observed in temperate northern hemisphere lakes where these organisms have been recorded previously. The majority of O. versatile colonies occurred in areas where thin orange-coloured films containing high concentrations of iron (> 60% Fe) covered the substrate and bedrock of the river; this may be related to the abundant picophytoplankton that were associated with these films and oligotrophic conditions. The planktonic diatom Gomphonema venusta Passy was dominant in the water column throughout the study period and acted as an environmental indicator of low electrical conductivity (EC) conditions in the habitat where O. versatile colonies were recorded.Articl

Trophic ecology and persistence of invasive silver carp Hypophthalmichthys molitrix in an oligotrophic South African impoundment

The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 μg l−1), and limited access to rivers considered large enough for successful spawning, has implications for their invasive potential in other systems. Stomach content and stable isotope analysis were used to assess the trophic ecology of H. molitrix, which was then compared with indigenous Mozambique tilapia Oreochromis mossambicus, on a seasonal basis during 2011. Hypophthalmichthys molitrix are generalist filter feeders, with a diet consisting primarily of sediment, vegetative detritus, dinoflagellates and diatoms. The dominance of sediments in their stomachs suggests occasional benthic scavenging. However, H. molitrix occupied a higher trophic level (TL = 2.8) than expected, suggesting that this population subsidised their diet with an unidentified dietary constituent, characterised by enriched nitrogen values. Although the stomach contents indicated dietary overlap between H. molitrix and O. mossambicus, stable isotopes revealed fine-scale resource partitioning, despite both species occupying the same trophic level. Nonetheless, the persistence of this feral H. molitrix population in an oligotrophic impoundment highlights their phenotypic plasticity

Bioaccumulation of aluminium and iron in the food chain of Lake Loskop, South Africa

Concentrations of total aluminium (Al) and iron (Fe) were determined in Lake Loskop over a period of four months in 2009 in samples of phytobenthos, phytoplankton, macroinvertebrates, amphibians and fish. The highest concentrations of Al and Fe were measured in the filamentous algae Spirogyra fluviatilis (Hillse) and Spirogyra adanata (Kütz), (Al=18,997.5 mg kg-1 dry weight and Fe=22,054.2 mg kg-1 dry weight) in the riverine zone of the lake with a near-neutral water average pH of 7.3. However, a negative correlation exists between the Al and Fe concentrations measured in the filamentous algae in comparison with the corresponding concentrations of these elements in the water column of the riverine zone. The Al concentrations in the macroinvertebrate families collected ranged from 140.6 to 385.7 mg kg-1 dry weight, with the highest values measured for Al and Fe in the family Gomphidae (385.7 and 1710.0 mg kg-1 dry weight, respectively) in comparison to other macroinvertebrate families sampled. Al and Fe concentrations (2580 and 10,697 mg kg-1 dry weight) in the stomach contents of adult Oreochromis mossambicus fishes were much higher in comparison with adult Micropterus salmoides fishes (98.5 and 439.6 mg kg-1 dry weight), respectively. In all cases of dissected fish species either white or yellow body fat was observed, thus in none of the samples both type of body fats occurred simultaneously. The concentrations of total Al and Fe in the different organs of O. mossambicus were along a mean sequence of intestine>yellow body fat>brain>gills>liver>heart>white body fat, while the mean sequence of total Al and Fe in M. salmoides was: intestine>gills>liver>heart>brain>white body fat. From the levels of Al detected in the yellow body fat of the studied fish species O. mossambicus, we suggest that this phenomenon may be related to the feeding habits of this species. Furthermore, the intake of certain species of phytobenthos by O. mossambicus could have played a role in the bioaccumulation of Al in the food chain and the possible development of pansteatitis in predators at higher trophic levels. © 2011 Elsevier Inc. All rights reserved.Article in Pres

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: α-alumina, γ-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 (5γg/kg); silica fume (5γg/kg, 50γg/kg); Sb2O5 (5γg/kg) and calcined silica fume (5γg/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. © 2011 Elsevier Inc.Articl