MechChem Africa November-December 2023

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CSIR researchers have deployed a buoy equipped with a series of instruments in Theewaterskloof Dam in the Western Cape, one of the largest dams in South Africa. CSIR deploys radiometric buoy to collect microalgae T o gain deeper insights into microalgae biodiversity and its significance in sup porting the ecosystem health of South Africa’s drinking water dams, research

ers from the CSIR have developed and deployed Africa’s first hyperspectral radiometric buoy in Theewaterskloof Dam in the Western Cape. The research team is employing a combina tion of satellite data and in-water physical and chemical measurements to assess microalgal diversity in near real-time. This approach will also enable the early detection of potential overgrowth of toxic algal species, which can negatively impact water quality and ecosys tem stability. The deployment and data collected will form part of the BioSCape research project, an international collaborative research project built on deep scientific engagement between South Africa and the United States of America. BioSCape is funded by the United States government through the National Aeronautics and Space Administration (NASA), the South African government through New Earth Observation Frontiers and via the South African National Space Agency, the National Research Foundation, South African Environmental Observation Network and the United Nations Educational, Scientific and Cultural Organization. The BioSCape project employs a combina tion of remote sensing and field data to gain insights into the distribution, functionality, and significance of biodiversity within the Greater Cape Floristic Region, recognised as one of the world’s 36 biodiversity hotspots. Biodiversity hotspots are regions that are bio logically diverse and facing significant levels of habitat loss and degradation. Approximately 70% of plant species found in the Greater Cape Floristic Region are endemic to the area. The growth and diversity of algae are closely linked to prevailing light conditions in their environment, and the instruments aboard the buoy are equipped to make precise measurements of the underwater light field together with algal growth parameters. Currently, Theewaterskloof Dam is ex periencing a significant sediment load due to recent floods in the area. The dam is typi cally regarded as seasonally eutrophic with algal blooms occurring during the summer months. Over the following three months, the anchored buoy, dubbed ‘Gizmo’, will be stationed in the dam, receiving regular visits for maintenance and upkeep. It is believed to be the only buoy in Africa that houses a

Left: Marie Smith, senior researcher at the CSIR, is seen taking measurements of the water height in the Theewaterskloof Dam during the deployment of CSIR’s ‘Gizmo’ buoy. Right: CSIR senior researcher Hein Swart is assisted by Francois Le Roux and Emile Lewis from Theewaterskloof Sports Club. The hyperspectral buoy is being used to assess micro-algal diversity in real-time.

hyperspectral underwater optical measure ment system. The buoy was developed by CSIR’s Centre for Robotics and Future Production, to meet specifications determined by the Earth Observation and Coastal Systems research group, in collaboration with other local sci entists and water quality management bod ies. It will serve as the main radiometric data collection and aquatic validation site for the BioSCape airborne radiometric project. The access-controlled area of the dam, in which the buoy will be deployed, is over seen as a nature reserve being managed by CapeNature. “CapeNature and the City of Cape Town must be acknowledged for their support of the BioSCape campaign, especially the Department of Water and Sanitation for the Theewaterskloof deployment,” says CSIR senior researcher, Lisl Lain. The historical occasion has been made possible through close collaboration, as is evident from the assistance by the Department of Water and Sanitation to secure permits for deploying the buoy in Theewaterskloof Dam. The sup port received from Theewaterskloof Sports Club played an instrumental role in ensuring the successful deployment of the buoy and is greatly appreciated by the CSIR. This CSIR-developed buoy has previously

been deployed on South Africa’s western and southern Cape coasts for harmful algal bloom research. “We have been updating the technology over the years to prepare for this Theewaterskloof Dam deployment moment in support of the high-quality data validation and vicarious calibration objectives of the BioSCape campaign,” says CSIR senior researcher, Marie Smith. From February to April 2024, the buoy will have a second deployment in Walker Bay for studies on similar water quality aspects. This is mainly in support of the aquaculture industry, which has suffered major financial losses over the years with toxic algae having become a huge threat to production. “We will undertake community outreach and information dissemination about the buoy and its role following the deployment,” says Lain. “Water quality is an issue affecting all South Africans and the pursuit of a low-cost monitoring system is key for the management of this essential resource.” The CSIR team will also be working with the NASA team members doing fieldwork from the middle of October until the end of November 2023 at some of the BioSCape target sites, namely Zeekoevlei, Rietvlei, Klein Rivier Estuary, Voelvlei Dam and Steenbras Dam. q

44 ¦ MechChem Africa • November-December 2023