Cantabrians are being reminded to check the status of local waterways for toxic cyanobacteria this summer, following more health warnings being issued for the region today. The Community and Public Health division of Canterbury District Health Board's latest warnings are for Rutherford Crescent Reserve pond located in Hanmer Springs, Lake Ellesmere/ Te Waihora and the Ashley River, immediately above the State Highway One bridge. The warnings come after the latest Environment Canterbury monitoring results show there are increased concentrations of potentially toxic cyanobacteria in these waterways. Dr Alistair Humphrey, Canterbury Medical Officer of Health, says people and animals should stay out of the lake until the health warnings have been lifted. The cyanobacteria in Lake Ellesmere are predominantly comprised of picocyanobacteria, which has been found to produce toxins in studies around the world and is particularly harmful to dogs. The Hanmer Springs cyanobacteria mostly comprises Anabaena, which visually gives a green "soupy" appearance to the water while the cyanobacteria at Ashley River at SH1 mostly comprises of Phormidium – a cyanobacteria which forms thick dark brown/black mats on the bed of the river. "People and animals, particularly dogs, should avoid these waterways. Animals that show signs of illness after coming into contact with lake water or Phormidium mats should be taken to a vet immediately." No one should drink the water from the lake at any time, Dr Humphrey says. "Boiling the water does not remove toxins. Symptoms from toxic exposure to the cyanobacteria range from rapid onset of nausea and diarrhoea, to gastroenteritis and other effects such as tingling and numbness around the mouth, fingertips, as well as liver damage," Dr Humphrey says. "If you experience any of these symptoms visit your doctor immediately and please let your doctor know if you have had contact with the lake water." Fish and shellfish can concentrate toxins and their consumption should be avoided. If fish are eaten, remove the gut and liver and wash in clean water. Environment Canterbury monitors the lake weekly during summer and the public will be advised of any changes in water quality that are of public health significance. Facts about cyanobacteria:
It occurs naturally but can increase rapidly during warmer months.
If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.
Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the blooms disappear.
Cyanobacterial concentrations can change quickly with changing environmental conditions (e.g. wind). If a health warning is in place avoid contact with the water.
For further information visit http://ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/lake-warnings.aspxOr contact Community and Public Health on (03) 364 1777.
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