Cyanobacteria found in two Southland rivers

2017-03-13T00:00:00 Pacific/Auckland

Date: 13.03.2017

Monitoring carried out by Environment Southland has shown high abundance of benthic cyanobacteria (blue-green algae) at two sites in Southland.

People and animals, in particular dogs, should avoid contact with reaches of the Hamilton Burn around Affleck Road and the Upukerora River around the Te Anau Milford Road until health warnings are removed.

Public Health South medical officer of health Dr Derek Bell says cyanobacteria produce toxins that are harmful to people and animals if swallowed or through contact with skin. Boiling water does not remove toxins and drinking of the water should be avoided at all times.

Exposure to cyanobacteria may cause symptoms such as skin rashes, nausea, tummy upset and tingling and numbness around the mouth or tips of fingers, he says.

Cyanobacteria concentrations can vary quickly with changing environmental conditions. Environment Southland's freshwater & marine science leader Nick Ward says cyanobacteria may be removed if river levels rise. However, if the warm, calm spell continues we could see more cyanobacteria developing in other rivers. It's good to know what you're looking for and to keep your eyes peeled.

Cyanobacteria occur naturally but can increase rapidly during warmer periods of the year. Benthic cyanobacteria usually occur as dark brown/black mats which grow attached to rocks in the river or accumulate on the surface in shallow, slow-flowing areas. They often have a strong, musty smell.

If you experience health symptoms after contact with contaminated water, visit a doctor immediately. Animals that consume cyanobacteria should be taken to a vet immediately.

Environment Southland monitors cyanobacteria monthly at a number of sites across Southland and the public will be advised of any changes in water quality that are of public health significance.

For further information, go to http://www.es.govt.nz/services/environmental-monit...