Cyanobacteria found in Waituna lagoon

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Toxic algae harmful to humans and animals has been found in high levels at Waituna Lagoon. Photo: Supplied

TOXIC algae harmful to humans and animals has been found in high levels at Waituna Lagoon, and people are being warned to stay clear.

Monitoring recently carried out by Environment Southland (ES) showed a “high abundance of planktonic cyanobacteria” (blue-green algae) in the lagoon.

An ES spokeswoman said planktonic cyanobacteria was different from that found in rivers during warmer months, but still produced toxins which could be harmful to people and animals if swallowed, or through contact with skin.

People and animals should avoid contact with the lagoon and be mindful of the potential health risks until health warnings were removed, she said.

“Cyanobacteria occur naturally, but can increase rapidly during warmer periods of the year.”

The ES website said favourable conditions for cyanobacteria also included low or stable river flows and the presence of nutrients.

Human activities, such as taking water from rivers or adding nutrients and sediment to waterways, could make things worse, the website said.

Another ES spokeswoman said ES had received funding to clean up the lagoon from the Government’s Fresh Start for Freshwater Clean-up Fund in 2012.

“The funding amounted to $785,000, which contributed to bank reconstruction work on Waituna Creek, the development of constructed wetlands and openings of the Waituna Lagoon between 2012 and 2015.”

A requirement of the funding was for the regional council to match it, and ES and its partners in the project had contributed $842,694.97, she said.

The Government’s clean-up fund totalled nearly $8 million intended for the clean-up of four of New Zealand’s most badly polluted rivers, lagoons and wetlands, including Waituna Lagoon.

Waituna Lagoon was originally allocated $780,000 from this fund.

ES had also received government funding for a range of research and investigation projects, she said.

The council also received $20,000 from the Ministry of Primary Industries for didymo and marine pest campaigns each summer, she said.

ES monitors cyanobacteria monthly at several river and lake sites across Southland, including the lagoon, and the public would be advised of any further changes in water quality of public health significance, she said.

The ES website said “toxic cyanobacteria are now known to be widespread in New Zealand waterways… [and] are widespread in Southland, being present in 96% of monitored sites in 2009. Southland’s most common cyanobacteria species… is known to produce neurotoxins… linked to reported dog and stock deaths in 1999/2000 in Southland. Since then there have been no confirmed cases of cyanobacteria-related animal deaths”.

Anyone who experiences health symptoms after contact with contaminated water should visit a doctor immediately. Animals that consume cyanobacteria should be taken to a vet immediately.

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