In 2020, the mysterious deaths of at least 350 elephants in Botswana’s Okavango Delta left the world puzzled and concerned. Four years later, scientists at King’s College London have identified the culprit: toxic cyanobacteria in standing water.
The Investigation
Using satellite data and spatial analysis, researchers discovered that 20 watering holes across 6,000 square kilometers had been contaminated with cyanotoxins, a toxic byproduct of certain cyanobacteria. After drinking from these waterholes, elephants traveled an average of 16.5 kilometers and succumbed within 88 hours of exposure.
Lead scientist Davide Lomeo explained that seasonal rain-fed pans, rather than permanent water bodies like lakes and rivers, were the primary sources of the cyanotoxins. The affected elephants ranged in age, and their intact tusks ruled out poaching as the cause of death. Interestingly, no other wildlife or livestock carcasses were found during aerial surveys, further focusing attention on the specific impact on elephants.
What Triggered the Algal Bloom?
Not all cyanobacteria are harmful, but some produce deadly algal blooms under specific environmental conditions. The study suggests that the shift from an exceptionally dry 2019 to an unusually wet 2020 likely disturbed sediment and nutrients, fueling algal growth in stagnant waterholes.
Lomeo highlighted that factors like rising water temperatures, nutrient loading, and salinity spikes are environmental triggers for the production of cyanotoxins.
Climate Change Implications
Scientists warn that incidents like this could become more frequent due to climate change. Southern Africa is projected to experience hotter and drier conditions, increasing the risk of harmful algal blooms in shrinking water sources.
The study emphasizes the urgent need for water quality monitoring to prevent such ecological tragedies in the future. This case underscores the broader consequences of climate change and the fragile balance of ecosystems dependent on water availability.
Read more Elephant News.