An assessment of the aquatic macroinvertebrate diversity within the Nyl River Floodplain system, Limpopo, South Africa.
Key finding
Poor management and gross incompetence at the Modimolle sewage treatment facility is destroying the Nyl and Mogalakwena rivers, threatening human health, and impacting the highly biodiverse Nylsvley Nature Reserve - South Africa's largest ephemeral floodplain
Overview
The intentions behind this study were to provide a comprehensive and holistic evaluation of the aquatic macroinvertebrate community assemblages present within the Nyl and Mogalakwena River system and their associated floodplain to determine the aquatic integrity of these systems. In addition to this, seasonality, water nutrients, sediment characteristics and metal concentrations (water samples) were analysed to correlate any impacts on the macroinvertebrate community assemblages to that of the water quality. The aims of this project were as follows:
i. To conduct a comprehensive assessment of the macroinvertebrate community assemblages along 10 sampling sites along the course of the Nyl and Mogalakwena River system and their surrounding wetlands.
ii. To correlate water nutrients and physico-chemical parameters with that of the macroinvertebrate community assemblages.
iii. To relate sediment characteristics along the course of the Nyl and Mogalakwena River system with that of the collected macroinvertebrate community assemblages.
iv. To identify possible anthropogenic impacts that might be affecting the river and the biota that are dependent on it.
To achieve the aforementioned aims, the following objectives were set:
The identification and classification of the aquatic macroinvertebrate taxa present within the system and their respective abundances.
An evaluation of the water quality from the Nyl and Mogalakwena River system by using the collected in situ water quality variables and by analysing collected water samples for nutrient loads. Additionally, collected water samples were analysed via ICP – OES to determine the extent of suspended and ionised metals in the water column.
An assessment of collected sediment samples by analysing their physical characteristics including particle size and organic content.
An investigation of the possible point sources of pollution or modifications to the river course that are having a negative effect on water and sediment quality, and therefore, the macroinvertebrate community assemblages that are present there.
Keywords
aquatic macroinvertebrates | ecotoxicology | sediment analysis | organic pollution | metal pollution | multivariate analysis | aquatic health | sewage effluent biomonitoring | South Africa | Limpopo Province
#biomonitoring #ICPOES #macroinvertebrates #communityecology #ecology #sediment #river #Modimolle #wastewater #southafrica #ecotoxicology #metal #pollution #environment #science #baseline #anthropogenic #water #limpopo #mogalakwena #organicpollution #metalpollution #sewage #sewerage #statistics #multivariate #aquatic #diversity #biodiversity #functionalfeedinggroups #SASS5
See associated publications:
Baker, N.J. & Greenfield, R. 2019. Shift happens: changes to the diversity of riverine aquatic macroinvertebrate communities in response to sewage effluent runoff. Ecological Indicators, 102, 813−821. https://doi.org/10.1016/j.ecolind.2019.03.021
Musa, R. & Greenfield, R. 2018. Use of diatom indices to categorise impacts on and recovery of a floodplain system in South Africa. African Journal of Aquatic Science, 43, 59-69. https://doi.org/10.2989/16085914.2018.1443907
Dahms-Verster, S., Baker, N.J. & Greenfield, R. 2018. A multivariate examination of 'artificial mussels' in freshwater ecosystems. Environmental Monitoring and Assessment, 190. https://doi.org/10.1007/s10661-018-6764-6
Dahms, S., Baker, N.J. & Greenfield, R. 2017. Ecological risk assessment of metals in sediment: A case study from Limpopo, South Africa. Ecotoxicology and Environmental Safety, 135, 106−114. https://doi.org/10.1016/j.ecoenv.2016.09.036
Musa, R., Gerber, R. & Greenfield, R. 2017. A Multivariate Analysis of Metal Concentrations in Two Fish Species of the Nyl River System, Limpopo Province, South Africa. Bulletin of Environmental Contamination and Toxicology, 98, 817-823. https://doi.org/10.1007/s00128-017-2100-z