Media release

ORC advise caution after Phormidium spotted in Kauru River

Wednesday 10 April 2019

The potentially-toxic algae can be deadly for dogs, who are attracted to its smell.

The public are urged to be on the lookout for potentially-toxic algae after ORC staff spotted Phormidium in the Kauru River at Ewings, west of Oamaru.

Environmental Resource Scientist Hugo Borges said that dogs are especially vulnerable to the algae, as they are inclined to eat it.

“While most of the warm and dry conditions that cause these algae blooms are behind us, there is still a risk of encountering Phormidium at certain spots, and it pays to be especially cautious with pets.

“The algal mats can detach from the river bed and accumulate along the water’s edge, making them more accessible to dogs. Dogs seem to like the smell of Phormidium, and it can cause severe poisoning and even death if they consume it,” said Dr Borges.

People are advised to avoid contact with the water, as exposure to Phormidium may cause symptoms such as skin rashes, nausea, and tingling and numbness around the mouth or tips of fingers.

ORC also advises that people learn how to recognise potentially-toxic algae in waterways, and look out for signage indicating water risks. Phormidium blooms under warm conditions and when river levels are lower, as low water levels are slower to flush it out. The algae appear in thick, dark brown or black mats on riverbeds, and may have a velvety texture and a musty smell.

If you suspect your dog has ingested Phormidium, contact a vet immediately. The most common signs that a dog might have consumed toxic algal material are lethargy, muscle tremors, fast breathing, salivation, twitching, paralysis and uncontrolled shaking, convulsions, or frothing at the mouth soon after being near the water.

This video from the Cawthron Institute has more information about Phormidium, including how it can be identified:


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