GabyLake Victoria — Africa’s largest lake and the world’s biggest tropical lake — is turning green. It borders Uganda, Kenya, and Tanzania, and it supports more than 47 million people. In recent years the lake has steadily changed color, according to IFLScience, because toxic algal blooms are spreading rapidly. That growth is tied to eutrophication, which happens when excess nutrients accumulate in the water from agricultural runoff, wastewater, industrial discharge, and even biomass and ash from forest fires. Global warming is making things worse: higher temperatures and more rainfall help the toxic algae flourish, researchers from the University of Michigan and Bowling Green State University in Ohio say.
What else have scientists discovered? The research team found that a widespread freshwater cyanobacterium, Microcystis, which causes blue-green algae blooms in the Winam Gulf of Lake Victoria, releases large amounts of the toxin microcystin. “The toxin damages the liver and can be lethal to livestock, poultry, wildlife, and people with weakened immune systems. In the Winam Gulf, microcystin levels often exceed the World Health Organization’s acceptable limits,” the team wrote. They also found that more intense algal blooms tied to the climate crisis have reduced oxygen levels and killed fish. In some parts of the lake the oxygen deficit is so severe the ecosystem can no longer support life.
Researchers are urging the governments of Uganda, Kenya, and Tanzania to modernize agricultural infrastructure and water treatment systems and to replant forests. Above all, they call for protecting land from destructive human activities to stop excessive nutrient runoff into the lake.
