February 11, 2009

MEDIA STATEMENT

Warning to Ashley River/Rakahuri dog owners, river users re toxic algae

A dog died this week after licking toxic algal mats near the lower reaches of the Ashley River/Rakahuri, North Canterbury.

Environment Canterbury (ECan) is warning people to be wary of swimming or allowing their dogs access to the lower reaches of the river because of the build-up of the toxic algae, Phormidium, in the lower river.

“As flows recede and water temperatures rise, conditions are ideal to promote the growth of Phormidium,” said Shirley Hayward, ECan water quality scientist. The North Canterbury river hasn’t had a flood since late December.

She points out that the Ashley River/Rakahuri has numerous access points so it is difficult to ensure people see warning signs. “People need to be aware and spread the word to be on their guard for the black or brown algae coating on river stones. They should not put themselves or their pets in danger by going into the water at these places or allowing their dogs to eat or lick the dried algae.”

A recent inspection of the river at SH 1 on Monday showed there was a build-up of Phormidium. Samples have been collected for toxin analysis. Two years ago, a severe bloom of this algae cause the death or illness of several dogs that had been in the riverbed.

The algae forms dense dark brown/black mats that are attached to stones, or when the mats break away, they accumulate at the river edge. Contact (skin contact, swallowing) can cause rashes, skin and eye irritation, allergic reactions, gastrointestinal upset, and other effects in humans. . The toxins can be fatal to dogs and they are particularly at risk because they like to scavenge near water.

Dr Alistair Humphrey, Medical Officer of Health, says people swimming or showering in water with increased levels of algal bloom have been known to develop allergic reactions – asthma, eye irritations, rashes, blistering around the mouth and nose and gastro intestinal disorders including abdominal pain, cramps and diarrhoea.

He says other users of the river, including fishermen and boat users should exercise caution. “For further information or in the case of illness or suspect illness after swallowing water containing algal bloom, seek advice from your doctor. If your animals become sick contact your veterinarian.”

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