Toxic algae warning for several Brussels ponds

Blue-green algae have been detected again in several Brussels ponds, according to Brussels Environment.

The unpleasant-smelling phenomenon is common on hot, dry summer days and can cause various health problems in humans and animals, Bruzz reports.

People and pets are therefore being urged to avoid the water in at least five Brussels ponds: the Rouge-Cloître pond in Auderghem, the big and little ponds of Etangs Mellaerts in Woluwe-Saint-Pierre, Flagey pond in Ixelles and the Leybeek pond in Watermael-Boitsfort.

Warning signs have been put up at the ponds in question and Brussels Environment spokesperson Lynn Tobback warns that the bacteria might be in more ponds and waterways.

Blue-green algae, also known as cyanobacteria, are bacteria that live in fresh water and closely resemble algae. They form a blue-green film on the surface of the water and, with sufficient light and high temperatures, the bacteria can reproduce explosively.

Brussels Environment said the root cause was pollution from feeding bread to birds. The small, uneaten food particles, as well as the birds' droppings, enrich the water, promoting the proliferation of cyanobacteria and other pathogenic microorganisms.

While not lethal, blue-green algae secrete toxic substances that are harmful to humans and animals upon contact or ingestion. They can cause headaches, nausea, rashes, nose and throat irritation or diarrhoea. The toxins can even damage the nervous system. Children, pets and aquatic flora are particularly vulnerable.

Brussels Environment said the Neerpede and Vogelzang pond in Anderlecht have not been affected. “However, cyanobacteria have been found there in the past, so we are keeping a close eye on them,” said Tobback.

“We are also closely monitoring the ponds in Tercoigne Park (in Watermaal-Bosvoorde) and King Baudouin Park (in Jette), where the situation seems suspicious, but where measurements currently show no cyanobacteria.”

Brussels Environment emphasised that it is not possible to determine with the naked eye whether a pond is affected by blue-green algae: “This requires measurements by experts.”