Cyanobacteria Research in Lake Victoria’s Winam Gulf

January 25, 2025

Recent research has focused on the genetic survey of cyanobacteria in the Winam Gulf of Lake Victoria, Kenya. This study, published in January 2025, is crucial for understanding harmful algal blooms (cyanoHAB) in freshwater ecosystems. The findings are expected to aid local authorities in tracking these blooms and provide insights applicable to other regions like Lake Erie in the United States.

What are Cyanobacteria?

Cyanobacteria or blue-green algae are not algae but have similar traits, like performing photosynthesis using chlorophyll, just like green plants.
They can exist as single cells, filaments (thread-like structures), or colonies of various sizes and shapes.
Cyanobacteria are found in all waterbodies, living in sediments or moving within the water.
Some species produce harmful toxins called cyanotoxins.

What are CyanoHABs?

CyanoHABs (Cyanobacterial Harmful Algal Blooms) occur when cyanobacteria grow rapidly in large numbers.
They often turn the water bright green, blue-green, or discolored, forming a surface scum or bottom mat that looks like pea soup or spilled paint.
These blooms can affect the environment by reducing dissolved oxygen (DO) levels, leading to the death of plants and animals.
CyanoHABs can also release toxins, causing health problems for humans and animals.
They are most visible on the water’s surface but can also gather near shorelines due to wind action.

Research Findings in Winam Gulf

The study revealed that cyanoHAB events are widespread in the Winam Gulf, not just in coastal areas.
In 2022, blooms were most prominent near Homa Bay.
By 2023, they expanded to areas like Bondo and the Yala River mouth.
The dominant species was Dolichospermum, with Microcystis present in lower quantities.

Survival Strategies of Cyanobacteria

Metagenomic analysis showed that cyanobacteria in the Winam Gulf employ various survival strategies. They utilise biosynthetic gene clusters (BGCs) to adapt to changing environmental conditions. The diversity of these BGCs in the Gulf is comparable to those found in western Lake Erie, indicating similar adaptive mechanisms.

Integrating Advanced Techniques for Monitoring

The study advocates for the use of advanced “Omics” techniques such as metagenomics, metatranscriptomics, and metabolomics. These methods can enhance research capabilities and inform effective water management strategies. This integration is vital for protecting both human health and aquatic ecosystems.

Key Facts About Lake Victoria

World Ranking: Largest tropical lake, largest lake in the African Great Lakes region, and the second-largest freshwater body globally by area.
It is shared by Kenya (6%), Uganda (43%), and Tanzania (51%).
Fishing Industry: World’s largest freshwater fishery, producing 1 million tons of fish annually.
Employment: Provides jobs to 200,000 people and supports the livelihoods of 4 million people.
The lake was formed 400,000 years ago. It dried out 17,300 years ago and refilled about 14,700 years ago.
Lake Victoria basin has about 40 million residents with a high population density (250 people/sq. km) and an annual growth rate of 3.5%—one of the world’s highest.
The lake was fed by rivers like Kagera, Katonga, Mara, and others; the Nile carries water out.

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