The threat of blue-green algae bloom looms over L. Victoria

Sub Levels

The lifeblood of East Africa, Lake Victoria stretches as far as the eye can see and is the largest freshwater lake in Africa and the second largest in the world.

The clear water reflects the bright blue sky above, and the colorful boats gently sway in the waves.

The coastline of Rambu Landing in Bukakata District, Masaka District is bustling with fishermen and merchants who sell their wares to locals and tourists. But there’s a problem beneath the surface.

A subtle greenish tint creeps across the lake, indicating algal blooms. This is a silent killer that threatens the delicate balance of the lake’s ecosystem, and can have unpleasant consequences if action is not taken soon.

Scientists and environmental activists clean up the Rambu landing site.

Scientists and environmental activists clean up the Rambu landing site.

The lake is in the spotlight after a mass die-off of fish in 2021. Several landing sites in Uganda were affected, including Kaseni, Kigungu, Bugonga, Guguda (green areas), Lido Beach, and Wagagi Flower Farm in Wakiso District. .

Others were Rambu, Kajir, Namirembe, Kachanga in the Masaka area, Kasensero in the Kyoji area, and others in the Greater Masaka area.

The same impact was felt in Kenya and Tanzania, as well as several African countries whose landing sites were affected. Environmental or climate change is believed to be the cause, but Ugandan scientists, conservationists and environmentalists have stepped forward to claim that algal and cyanobacterial blooms are to blame. involved in the death of fish.

They warn that these flowers, known locally as mbil or nkonge, can harm aquatic life by blocking sunlight and clogging fish gills.

This situation often causes fish death, anxiety and disorientation.


Fishermen at the Bukakata, Rambu and Casencero landing sites say they lack the expertise and scientific knowledge to deal with marine blooms and invasive plant species.

Mr. Antonio Kalyango, Executive Director, Biodiversity Conservation Forum

Mr. Antonio Kalyango, Executive Director, Biodiversity Conservation Forum

According to Joseph Chimera, a fisherman and city councilor of Casencero, the Kagera River brings in large numbers of exotic plant species from Burundi, Rwanda and Tanzania every day.

But a wide range of pollutants pose serious threats to the health of people, ecosystems and economies in surrounding areas, he said.

Yassin Sentam, chairman of Kagera Cell10, explains that while some fish species can tolerate blooms, Nile perch are usually forced out of infected areas in search of fresh water.

Excess algae can be deadly to fish. As a result, fish species that require higher levels of dissolved oxygen may migrate deeper into lakes in search of suitable conditions, which could lead to fish shortages, he added.

“Tilapia and African lungfish are among the fish species that can survive in polluted waters and coexist with organisms that thrive in such environments. Despite the presence of algal blooms, they tend to avoid such sites. “Unlike the Nile perch, which has a fin, these fish can still be caught with nets,” he says.

environmental authorities

Rose Nakieziwe, Masaka District Environment Officer, said blue-green algal blooms thrive in areas with excess nutrients such as phosphorus and nitrogen.

These nutrients are typically introduced into water by runoff from terrestrial sources such as animal waste, manure, and sewage.

As a result, blooms deplete oxygen levels in the water and can lead to asphyxiation in fish, especially those sensitive to low oxygen levels such as Nile perch, tilapia, haplochromin, and rustneobora.

Rising water levels in Lake Victoria flood homes at Rambu landing site

Rising water levels in Lake Victoria flood homes at Rambu landing site

“Similar to water hyacinth and birch grass, algae and cyanobacterial blooms are considered exotic plant species that tend to be replaced by native species, causing ecosystem imbalances and promoting algal growth. ,” Nakieziwe said.

A surge in agricultural activity and the use of fertilizers, pesticides and fungicides on lakeshores are thought to be the main causes of bloom growth.

“Such pesticides, liquid and solid industrial waste, and soil commonly run into lakes, leading to elevated nutrient levels,” she explained.


According to a 2020 study on harmful algae, researchers found that Lake Victoria (LV) was undergoing a process of gradual eutrophication that resulted in significant changes in fish populations, causing water hyacinths, algae and cyanide to grow. It states that the bacterial outbreak is recurring.

Mark Orocotum, a research fellow at the National Fisheries Research Institute (NaFIRRI) and one of the study’s authors, says the presence of cyanobacterial blooms has two main effects on fish communities. .

First, the environmental conditions in which the fish live can change, adversely affecting the abundance and diversity of fish populations in Lake Victoria.

Second, cyanotoxins can accumulate in fish, posing a risk to human populations consuming these contaminated fish.

According to Olokotum, concentrations of microcystin (MC), a toxin produced by certain species of cyanobacteria (blue-green algae), can be toxic to humans and animals when ingested in large amounts, making cyanobacteria widespread. is a cause for concern in waters where bloom.

“Bacterial decomposition of the organic matter produced by cyanobacteria in lakes can lead to severe oxygen depletion throughout the water column of deep lakes and shallow lakes,” he says, which can harm fish communities and ecosystems. added that it could affect The study further highlights the lack of information about potential health risks for people directly using Lake Victoria water for activities such as cooking, washing and recreation during cyanobacterial blooms. .

Casencello Town Council Member Joseph Chimera

Casencello Town Council Member Joseph Chimera

Apart from the potential risks associated with consuming untreated or treated water and contaminated fish, cyanobacterial blooms directly and indirectly affect the cost and availability of drinking water produced by treatment facilities. Researchers point out that it may give

environmental activist

The Biodiversity Conservation Foundation (BCF), Green Climate Campaign Africa (GCCF) and Fridays for Future Uganda environmental advocates recently released pollutants such as invasive aquatic weeds, algae and plastic from Lake Victoria. launched a campaign to

Launched at Rambu Landing Site, Bukakata Upazila, Masaka District, the campaign aims to increase solid waste collection at various landing sites throughout Masaka metropolitan area to ensure proper sanitation and safety of water. is.

Despite the efforts of the Uganda-Egypt Aquatic Weed Control Project to eradicate water hyacinth, Lake Victoria still remains a major neglected algae issue.

The Executive Director of the Biodiversity Conservation Forum (BFC), Antonio Carillango, said the government is allocating sufficient resources to eliminate invasive algae species and address other issues affecting the lake and its ecosystem. pointed out no.

To address this problem, he says, environmentalists and NGOs are working together to educate communities around the lake about the importance of protecting the lake from bloom pollution.

Following fish die-offs, BCF study reveals alarming levels of lake pollution from solid waste dumping and encroachment into watersheds by farmers using chemicals that run into lakes became.

For example, the Rwera and Rutembe watersheds were allotted to investors for development, exacerbating the problem.

Plastic pollution remains a significant challenge, but people should also pay attention to other factors that contribute to lake pollution.

Authorities should reconsider the argument for permitting the use of chemicals in the basin and take appropriate measures to prevent toxic substances from entering the lake.

GCCF Executive Director Timothy Mugeluwa called on the government to support efforts to conserve the lake and improve sanitation at the landing site.

He said the lake is being affected not only by climate change, but also by human activity, which needs to be taken into account.

Recent studies suggest that plastic waste and climate change are major causes of lake degradation, leading to the presence of toxic chemicals and solid wastes that affect water quality.


Despite the seriousness of the situation, experts say more can be done to protect the lake, fish and water quality.

They highlight the need to invest in solutions such as early warning systems to detect algae outbreaks, effective management of agricultural and industrial sectors to reduce nutrient runoff, and promotion of sustainable fishing practices. I am emphasizing.

They also emphasize the need to raise public awareness about the dangers of consuming toxic algae that can harm both fish and humans.

With these measures, experts believe it is possible to curb blooms and protect Lake Victoria’s ecosystem for future generations.

Other solutions include reducing nutrient contamination.

Algae grow using nutrients such as nitrogen and phosphorus from agricultural and urban runoff.

By reducing nutrient pollution, you can limit the growth of harmful algae and prevent them from taking over the lake’s ecosystem.

They say that promoting sustainable fishing practices, such as using selective fishing gear and avoiding fishing during breeding season, can help maintain healthy fish populations and support long-term fish production. .

Source link

Leave a Reply

Your email address will not be published. Required fields are marked *