New sensors deployed in Lake Victoria recorded oxygen levels collapsing before fish deaths were reported, demonstrating the potential for earlier warning of environmental hazards.
Researchers from King's College London have recorded the warning signs of a major low-oxygen event in Lake Victoria just hours before fish deaths were reported by local communities, providing a powerful demonstration of why earlier warning systems are urgently needed.
The discovery came only days after researchers deployed pilot water quality sensors at aquaculture sites near Dunga Beach, Kisumu, as part of a project to develop new tools for monitoring and anticipating water quality hazards. The sensors recorded dissolved oxygen levels falling to almost zero before reports emerged of fish deaths in the same area.
The deployment forms part of the FRESH-WQ project, a collaboration between King's College London, the Kenya Marine and Fisheries Research Institute (KMFRI) and the African Centre for Aquatic Research and Education (ACARE). The project aims to combine low-cost sensors, satellite observations and artificial intelligence to help communities anticipate hazardous water quality conditions before they cause significant losses.
Naing Oo, Senior Technician in the Department of Geography's John B. Thornes Laboratory, was monitoring data from the newly installed sensors when the readings suddenly changed.
"When I saw the dissolved oxygen readings suddenly fall to almost zero, I honestly thought there must be a problem with the sensors because the values were so extreme.
"The following morning, we received reports of fish deaths from the same area at Dunga Beach, Kisumu, Kenya.
"It was heartbreaking to hear about the losses experienced by local fish farmers, but it also showed the value of continuous, real-time monitoring. It reinforced why we're developing affordable monitoring systems that, combined with forecasting, could one day provide communities with advance warning so they have time to respond before these events become disasters."
Fish deaths linked to hypoxia - a condition in which oxygen levels in the water become dangerously low - can devastate aquaculture operations and threaten livelihoods around the lake. Researchers and local stakeholders are increasingly concerned that environmental pressures including pollution and climate change may increase the frequency and severity of such events.
The King's-led project is seeking to address a significant gap in environmental management. While forecasting systems are widely used for weather, floods and droughts, tools capable of anticipating water quality hazards remain rare, particularly in regions where monitoring infrastructure is limited.
During a stakeholder workshop held alongside the fieldwork, fish farmers, researchers and community representatives described how they currently rely on local knowledge to assess changing lake conditions, including observing water colour, fish behaviour and other environmental indicators. Participants said that the ability to predict hazardous conditions weeks in advance would be particularly valuable for managing risks to fisheries and aquaculture.
Dr Emma Tebbs, Senior Lecturer in Physical Geography and Earth Observation at King's College London, said:
"Stakeholders told us that they already have extensive knowledge of the lake and how conditions change. What would be most useful is the ability to look ahead.
Our goal is to combine satellite observations, environmental sensors and AI to develop systems that provide advance warning of emerging hazards, giving communities more time to make informed decisions."
The pilot sensors continuously collect water quality data and transmit information in near real time. Future phases of the project will integrate these measurements with satellite-derived environmental observations and AI models designed to identify patterns associated with deteriorating water quality. The long-term ambition is to create an operational forecasting system capable of supporting fisheries, aquaculture and water management across the African Great Lakes region.
For the research team, the events at Dunga Beach provided an unexpected test of the technology and a stark reminder of the real-world importance of the work.
"For me, this project isn't just about the technology," said Naing Oo.
"It's about community, citizen science, building lasting partnerships, supporting the next generation of scientists and engineers, and working together across countries to develop practical solutions that make a real difference to both people and freshwater ecosystems."
FRESH-WQ is funded by King's Climate & Sustainability Seed Fund.
