Glenneis Kriel
Cyanobacteria form a green, unpleasant smelling scum on the water surface, and leave a blue-green tinge along the sides of a dam when it dries out.
Farmers have been warned to be on the lookout for cyanobacterial blooms in water bodies, which can be lethal for both humans and animals, and are currently very prevalent.
According to CyanoLakes, a company that uses satellite imagery to monitor cyanobacterial blooms, blooms posing a very high health risk had been widely reported in the past week.
Cyanobacteria were found in a wide range of environments, but were generally present below the threshold of concern, according to Plant Poisoning and Mycotoxicosis of Livestock in Southern Africa. The microorganisms were only considered a threat during the bloom period, which usually occurred during the summer months, and primarily in dams with low and stagnant water levels.
During bloom episodes, the bacteria, depending on the subspecies and environmental conditions, secreted toxic metabolites into the water. These toxins had been found to induce conditions ranging from headaches, vomiting and skin irritation to being associated with Alzheimer’s disease in humans, and lameness and liver damage in livestock.
People and animals could recover without treatment if they ingested low volumes of contaminated water, but no treatment was available for high levels of ingestion.
Jurgens van Loggerenberg, managing director of Water Technovation and director of operations in South Africa for BlueGreen Water Technologies, said the situation had worsened over time, due to climate change, but was primarily the result of water pollution.
“The build-up of artificial fertilizer in combination with poor sanitation, resulting in high levels of sewage running into dams, is creating a nutrient-rich environment for these bacteria to thrive in.” He estimated that about 60% of farm dams in the country were affected by cyanobacteria blooms at one time or another, every year.
He said it was relatively easy to identify cyanobacterial blooms, as the bacteria reproduced quickly during bloom periods and then formed a green, unpleasant smelling scum on the water surface with a sponge-like feel to it, and left a blue-green tinge along the sides of a dam when it dried out.
He advised farmers to move their animals away from water bodies affected by these algal blooms, and seek treatment for dams in which blooms occurred.
“The dams need to be treated, otherwise the bacteria will over-winter and pose a threat the next warm season.”
-Farmers Weekly