Impact of Alluvial Diamond Mining on Macroinvertebrate Community Structure in the Lower Vaal River, Northern Cape Province in South Africa

The study aimed to assess the impact of alluvial diamond mining on macroinvertebrate community composition at four selected sites in lower Vaal River in 2016 with the application of the South African Scoring System 5 (SASS5). Macroinvertebrates and physico-chemical water parameters such as pH, turbidity, electrical conductivity and dissolved oxygen were measured seasonally. Turbidity levels were high 5.98.0±0.63 NTU but never exceeded the water quality guidelines of aquaculture, whilst pH values did not vary much and were generally alkaline throughout the study. The macroinvertebrate community structure varied at all sites during the study period. Site 4 was the most impacted site dominated by the more tolerant macroinvertebrates such as Simuliidae, Baetidae and Gyrinidae. The study concludes that although alluvial diamond mining had a negative impact on macroinvertebrate community in the short-term period, they appeared to re-establish quickly once the mining operations stopped.

Responses of macroinvertebrate community metrics to urban pollution in semi-arid catchments around the city of Bulawayo, Zimbabwe

River health monitoring is becoming increasingly important because of the anthropogenic activities that continue to impact on water quality and biodiversity of aquatic systems. This study aimed at identifying and evaluating macroinvertebrate community-based metrics that best respond to degradation due to urban pollution in riverine systems of Bulawayo, Zimbabwe. Data (physicochemical variables and macroinvertebrate specimens) were collected from 17 sites over 3 seasons. The sites were selected across an impairment gradient comprising less impacted, moderately impacted and heavily impacted sites. Heavily impacted sites had the highest levels of total dissolved solids, conductivity, salinity, turbidity, total phosphates, total nitrogen, chemical oxygen demand and sedimentary zinc. Dissolved oxygen was significantly highest in less impacted sites. Sensitivity of 24 macroinvertebrate metrics to this impairment gradient were assessed. A total of 5 metrics were identified as sensitive to modifications in water quality due to urban pollution. These metrics were taxon richness, South African Scoring System (SASS5) score, average score per taxon (ASPT), percentage collectors and percentage scrapers. The selected metrics will be useful for the monitoring and assessment of the studied riverine systems and can be further integrated into one multimetric index that combines a range of indices and allows the integration of ecological information for better management of aquatic ecosystems in this region.

The Influence of Anthropogenic Activities on Macro-Invertearates Assemblage and Water Quality in the Crocodile River (East) Mpumalanga, South Africa

<em>Biological indicators such as macro-invertebrates and water quality parameters can give an overalln overview of what is happening in a river catchment. The aim of the study was to determine the influence of anthropogenic activities on macro-invertebrates assemblage and water quality using multivariate analysis and to determine the present ecological state of the river using the Macro-Invertebrates Response Assessment index. The South African Scoring System Version 5 (SASS 5) was used to collect macro invertebrates. Water quality samples were collected using a polyethylene bottle and analysed by Mpumamanzi Laboratory in Nelspruit and Water lab in Pretoria. From the results obtained it was evident that anthropogenic activities along the Crocodile River play a role in water quality deterioration and the subsequent distribution of macro-invertebrates during high and low flow conditions. The main anthropogenic activities contribute to the influence of macro-invertebrates community and water quality are agricultural activities in the upper reaches and a combination of industrial, domestic, mining and agricultural activities in the middle and lower reaches of the Crocodile River.</em>