Council for Scientific and Industrial Research (CSIR) researchers have deployed a buoy equipped with a series of instruments in Theewaterskloof dam, in the Western Cape, to gain deeper insights into microalgae biodiversity and its significance in supporting the ecosystem health of South Africa’s drinking water dams.

The research team will employ a combination 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 ecosystem stability.

The growth and diversity of algae are closely linked to the 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 experiencing a significant sediment load owing to the recent floods in the area. The dam is typically regarded as seasonally eutrophic with algal blooms occurring during the summer months.

Over the following three months, the anchored buoy will be stationed in the dam, and receive regular visits for maintenance and upkeep. It is believed to be the only buoy in Africa that houses a hyperspectral underwater optical measurement system.

The BioSCape project employs a combination of remote sensing and field data to gain insights into the distribution, functionality and significance of biodiversity within the Greater Cape Floristic Region, which is recognised as one of the world’s 36 biodiversity hotspots.

Biodiversity hotspots are regions that are biologically diverse and facing significant levels of habitat loss and degradation. About 70% of plant species found in the Greater Cape Floristic Region are endemic to the area.

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 and in collaboration with other local scientists and water quality management bodies.

The buoy 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 overseen as a nature reserve being managed by CapeNature.

The project was 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 and the collaboration with CapeNature and the City of Cape Town.

“The support received from Theewaterskloof Sports Club played an instrumental role in ensuring the successful deployment of the buoy and is greatly appreciated by the CSIR,” said CSIR senior researcher Dr Lisl Lain.

In the coming weeks, the CSIR team will also be working with the National Aeronautics and Space Administration (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, Voëlvlei dam and Steenbras dam.

Meanwhile, the 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 moment to deploy the buoy in Theewaterskloof dam in support of the high-quality data validation and vicarious calibration objectives of the BioSCape campaign,” says CSIR senior researcher Dr Marie Smith.

From February to April next year, 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. 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,” says Lain.

Meanwhile, BioSCape is funded by the US government through Nasa and by the South African government through the New Earth Observation Frontiers via the South African National Space Agency and the National Research Foundation, as well as the South African Environmental Observation Network and the United Nations Educational, Scientific and Cultural Organisation.

The deployment of the buoy and the data collected will form part of the international collaborative research project BioSCape research project, which builds on deep scientific engagement between South Africa and the US.