Harare, (New Ziana) –The ecological balance of Lake Kariba is under threat from fish diseases, primarily caused by parasites and exacerbated by pollution from sewage, mining, and agriculture waste, an expert has said.
Aquatic ecologist at the University of Zimbabwe Faculty of Sciences’ Biological Sciences Department Dr Lightone Marufu said this on Mondy. Dr Marufu is also the Department’s representative at the University of Zimbabwe Lake Kariba Research Station based at Kasese Bay.
He said the diseases hinder fish reproduction, leading to decreased yields. “Parasites like nematodes and cestodes, including parasitic tapeworms, infect some fish in Lake Kariba. Areas near sewage discharge points often experience higher disease prevalence due to poor water quality,” he said.
“This compromised water quality harms fish gills and other sensitive organs, making fish more vulnerable to diseases and impacting their growth and reproduction.”
Invasive species, particularly crayfish from Australia, further threaten fish populations as they consume local fish as well as damage catches while they remain in fishing nets, with research indicating that they also disrupt the natural ecosystem, degrade biodiversity, and ultimately pose risks to human health.
The impact of fish diseases extends beyond the aquatic environment, affecting the livelihoods of local fishing communities as many families along the Lake Kariba shoreline rely on fish trade for their income, and when reports of diseases or invasive species emerge, they often panic, fearing declines in fish quality and market returns.
Dr. Marufu said climate change also exacerbates the issues, stating, “Climate change can trigger disease outbreaks by altering water quality and availability. Changes in temperature and irregular water inflow and outflow can disrupt entire ecosystems.”
He warned that without effective mitigation and adaptation strategies, both biodiversity and the livelihoods dependent on Lake Kariba could suffer significant losses.
To combat the challenges, the University of Zimbabwe is collaborating with government agencies and stakeholders to monitor and report on fish diseases, invasive species, and water quality, including conducting studies to inform management decisions that protect the lake’s ecosystem.
Dr Marufu highlighted the importance of disseminating research findings to all stakeholders, particularly affected communities.
“Raising awareness of potential threats to fish and livelihoods is crucial for effective management,” he said.
“As Lake Kariba faces these multifaceted challenges, ongoing research and community engagement will be essential to safeguard both the ecological integrity of the lake and the health of local populations.”
New Ziana
