In 2020, at least 350 elephants died under mysterious circumstances in Botswana, sparking global concern and confusing scientists about the reason for the deaths. Four years later, A study conducted at King’s College London may have finally found the answer. According to the study, a “poisonous concoction” of open water contaminated by a strain of cyanobacteria that releases cyanotoxins, which contaminated watering holes in the region, led to mass deaths of elephants.
Combining satellite data and spatial analysis, the study found that as many as 20 waterholes in the Okavango Delta were contaminated over an area of about 6,000 square kilometers. After drinking, elephants were estimated to have walked an average of 10 miles (16.5 km) from the toxic waterholes and died within about 88 hours of exposure.
“Our results highlight that seasonal, primarily rain-fed pans, and not the permanent water bodies (i.e. lakes, rivers and lagoons) within the Panhandle, were the likely source of cyanotoxin exposure,” said Davide Lomeo, the lead scientist of the Panhandle. study.
Strikingly, the dead elephants were of different ages, with tusks intact, leading scientists to rule out death from poaching. In addition, no carcasses of other wild animals or livestock species were observed during any of the aerial surveys.
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What promoted algae growth?
Not all cyanobacteria or blue-green algae are poisonous, but some cyanobacteria produce a type of deadly algae blooms (HABs) in standing water. According to the study, the shift from a dry 2019 (the driest year in decades in the region) to an extremely wet 2020 may have given rise to the unprecedented algae growth due to the resuspension of significant amounts of sediments and nutrients from the soil.
“Scientists believe that the production of cyanotoxins is related to certain environmental factors, for example a sudden increase in water temperature, nutrient levels and salinity,” said Mr Lomeo.
Scientists have warned that such incidents will become more common in the future due to climate change.
“South Africa is expected to become drier and hotter under the influence of climate changes, and as a result, waterholes in this region are likely to be drier for more months of the year. Our findings highlight the potential negative impacts on water quantity and quality , and the This could have catastrophic consequences for animals.
The study underlines the serious ecological consequences of the accumulation of toxic algae, while emphasizing the crucial need for water quality monitoring in water bodies, including the smallest.