The toxic algal bloom found in Lake Waihola and the Tomahawk
Lagoon in the past two days can cause illness in humans and
be deadly to dogs, the Otago Regional Council says.
The council is warning the public that they and their animals
should avoid contact with the potentially toxic dark
blue-green algal bloom in Lake Waihola, south of Dunedin, and
the upper Tomahawk lagoon in Dunedin.
Director of environmental information and science John
Threlfall said this algae could cause illness in humans and
be fatal to dogs.
Otago-Southland medical officer of health Dr Marion Poore
said people swimming in water with the bloom had been known
to develop allergic reactions such as asthma, eye
irritations, rashes, blistering around the mouth, and nose
and gastro-intestinal disorders, including abdominal pain,
cramps, and diarrhoea.
The higher the concentration of toxins, and the longer the
contact with the water, the more severe the symptoms were
likely to be so people or animals should not swim in the lake
or lagoon and fishermen and boat users should exercise
caution, Dr Poore said.
Dogs and livestock were particularly susceptible to algae
poisoning because they could consume the algae and should be
given alternative drinking water.
Symptoms of poisoning in animals included lethargy, muscle
tremors, fast breathing, twitching, paralysis and
convulsions. In extreme cases, death could occur in animals
within 30 minutes of the initial symptoms.
If illness was suspected from swallowing water with algal
bloom people should contact their doctor for medical advice
and if an animal became sick, owners should contact their
veterinarian immediately, Dr Poore said.
The council would place warning signs about the bloom at the
lake and lagoon.