In the heart of Ethiopia, Lake Tana, a UNESCO World Biosphere Reserve, is facing unprecedented challenges. As the largest lake in the country, it holds 50% of Ethiopia’s freshwater and is surrounded by fertile land that has long supported agriculture, urbanization, and irrigation. However, these very activities are now threatening the lake’s delicate ecosystem. A recent study published in ‘Aquaculture, Fish and Fisheries’ (translated as ‘Aquaculture, Fish and Fisheries’), led by Degsera Aemro from the Department of Fisheries & Aquatic Sciences at Bahir Dar University, sheds light on the critical role of buffer zones in maintaining the health of this vital water body.
The study, conducted from December 2020 to May 2021, collected data from buffered zones, non-buffered zones, and the pelagic area of the northern and northeastern parts of Lake Tana. The findings reveal significant spatial variability in water quality and plankton composition, highlighting the urgent need for conservation efforts.
“Buffer zones act as a natural filter, trapping sediments and nutrients before they enter the lake,” explains Aemro. “When these zones are degraded, as seen in Seraba and Kirrigna, the lake’s water quality suffers, impacting both plankton diversity and overall ecosystem health.”
The research identified key differences in water parameters across sites. Degraded buffer zones showed poorer conditions, with lower dissolved oxygen levels and higher nutrient concentrations. Phytoplankton communities were dominated by Chlorophyceae, followed by Bacillariophyceae, Cyanophyceae, and Euglenophyceae. Notably, Microcystis, a genus of cyanobacteria, was prevalent across all sites but less so in the buffer zone area.
Zooplankton composition also varied significantly, with Rotifera dominating over Copepod and Cladocera. Chlorophyll-a (Chl-a) concentrations, an indicator of phytoplankton biomass, were highest in buffered and pelagic areas, showing positive correlations with dissolved oxygen and negative correlations with temperature and turbidity.
The study’s findings have significant implications for policymakers and stakeholders. “Human activities are significantly impacting water quality and plankton diversity,” Aemro warns. “Protecting and restoring Lake Tana’s buffer zones is crucial for the sustainable utilization of this vital resource.”
The commercial impacts of this research are far-reaching, particularly for the energy sector. Lake Tana is a critical water source for hydropower generation, and maintaining its water quality is essential for the efficient operation of power plants. Additionally, the lake supports a thriving aquaculture industry, which relies on healthy plankton populations for fish feed.
As Ethiopia continues to develop, balancing economic growth with environmental conservation will be key. This research underscores the importance of protecting buffer zones, not just for the sake of the lake’s ecosystem but also for the long-term sustainability of industries that depend on it.
In the words of Aemro, “The health of Lake Tana is a reflection of our stewardship of the environment. It’s time we take action to protect it for future generations.”