30 January 2008
Be Wary of Algal Mats in Rivers
Hawke’s Bay Regional Council and Hawke’s Bay District Health Board’s medical officer of health say people using the
Tukituki River should be wary of blue-green algal (cyanobacteria) mats. These mats appear on riverbanks and perhaps on
the surface in shallow areas.
A sample taken from the Tukituki River on 25 January above Red Bridge indicated the presence of a potentially toxic form
of the algae. Regional Council scientists have done further sampling as a follow up. The Council is still waiting on
final results.
The algae exist in rivers naturally, but can form mats in continuing warm, dry weather and low river flows. These mats
can become toxic.
When algal mats become exposed and easily accessible to people, dogs, and stock they become a health risk.
The cyanobacteria mats are identifiable by a strong musty odour and can vary in colour from dark green/brown to a pale
brown/whitish colour when dry.
The Medical Officer of Health says that any contact with the toxic form of the mat may cause vomiting, diarrhoea and
skin irritations in humans. Dogs are particularly susceptible to the toxins and owners are advised to avoid allowing
their dogs to scavenge on the river’s edge.
If any person displays signs of illness after being in a river bed, seek medical advice from a doctor immediately.
Similarly, any dogs or other animals that get sick after being in a river should get prompt veterinary attention.
ENDS