The Otago Regional Council is again warning dog owners about the dangers of toxic algae in waterways, as temperatures begin to rise and river levels begin to drop.
Toxic algae were confirmed in the Cardrona and Manuherikia rivers last summer and two dogs died after consuming the algae in the Cardrona River.
Otago Regional Council director of engineering, hazards and science Dr Gavin Palmer said the toxic algae would also have been present in other streams and waterways in the region.
Cyanobacteria occurs naturally in waterways, but can become a problem in summer when the algae can form thick mats on river beds, especially during low flows. Some cyanobacteria produce toxins that are a possible health risk to humans and animals if consumed, and they can also cause irritation to the skin and eyes. There have been cases in New Zealand of dog deaths associated with toxic algae in which dogs have eaten the mats formed by the cyanobacteria species phormidium.
Phormidium mats produce a deep earthy odour attractive to dogs, and dogs are at greater risk because they are more likely to consume the algae.
Dr Palmer said the risk to dogs was greatest when phormidium mats became detached from the river bed and collected at a river’s edge where dogs could reach them easily.
“If the bed of a river is covered in thick dark brown or black mats that have a velvety texture and a musty smell, it is wise to be cautious and avoid that river site.”
Dr Palmer said while the council was not able to monitor throughout the region, it was important people using waterways were aware of the risks associated with toxic algae and alert to its possible presence wherever they were in Otago.