Potentially toxic blue-green algae found in Otago

December 6, 2012

Potentially toxic blue-green algae found in Otago

The Otago Regional Council (ORC) is warning the public to avoid contact and keep their dogs away from two popular Otago swimming locations after the discovery of potentially toxic algal blooms over the past two days.

ORC director of environmental information and science John Threlfall said Lake Waihola south of Dunedin and the upper Tomahawk lagoon contain the potentially toxic blue-green algae Anabaena lemmermannii.

This algae, which is dark green, can produce a series of toxins which are then passed to the water and can be fatal to dogs and cause illness in people.

Otago-Southland medical officer of health Dr Marion Poore said people swimming 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.

People should not swim in Lake Waihola and Tomahawk lagoon, and other water users, including fishermen and boat users, should exercise caution, Dr Poore said.

Any reaction depends on the type of toxins present, and the concentration of the toxin in the water. The higher the concentration of toxins and the longer the contact with the water, the more severe the symptoms are likely to be.

Dogs are particularly susceptible to poisoning from both mat-forming and free-floating toxic algae as they enjoy being in the water and can consume these algae intentionally or by accident. Livestock are also at risk from poisoning from cytotoxins and should be provided with alternative drinking water.

Symptoms of poisoning in animals exposed to the type of toxins present in anabaena mats include lethargy, muscle tremors, fast breathing, twitching, paralysis, convulsions. In extreme cases, death can occur within 30 minutes after signs first appear.

“In the case of illness or suspected illness after swallowing water containing algal bloom, seek advice from your doctor. If your animals become sick, contact your veterinarian immediately," Dr Poore said.

ORC will put out warning signs at the locations where the algae has been found and will continue to monitor the situation.

ENDS

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