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Warning about toxic algae in Tukituki

Phormidium web2

Water quality monitoring by Hawke’s Bay Regional Council staff has prompted warnings from Hawke’s Bay District Health Board about the health risks of potentially toxic algae on the Tukituki River.

Parts of the Tukituki River are prone to algal growth in summer, due to lower water flows, higher water temperatures and nutrients in the water. 

Green strand algae is harmless but black Phormidium bacteria growth on the rocks is potentially toxic for humans and dogs.  It can detach from the rocks and dry as mats on the sides of the rivers, and these can also be toxic.

“Our advice is to always treat the black growth on rocks in the water and the drying mats as toxic, stay out of the water if you see it, and swim or walk your dog elsewhere,” says HBRC’s Senior Environmental Scientist Anna Madarasz-Smith.

She adds that science has not yet identified when Phormidium turns toxic or why, so to be safe it should always be treated as harmful.

  • Contact with Phormidium bacteria can make people sick, with flu-like symptoms.
  • Dogs are more vulnerable. They are particularly attracted to the odour of the mats and being smaller, the toxins can be more dangerous.  Dogs should be under control in river beds and not allowed to scavenge.  Clinical signs are vomiting, diarrhoea and lethargy, and heat stroke- like symptoms such as muscle tremors, breathing difficulties, paralysis and convulsions.

People can check water quality and algae warnings here which displays data from LAWA (


29 January 2018

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