Algal blooms come in early on Hutt River

A summer of deadly algae is upon us

SUPPLIED   The Phormidium algae growing on this rock often produces a toxin that can kill dogs in just half an hour if eaten.

Stuff,

15 December, 2014

Playing at the river's edge this summer could prove fatal for Wellington and Wairarapa dogs.

The deadly algae that killed five dogs by the Hutt River one summer looks set to appear in the Hutt, Ruamahanga and Waipoua Rivers again this year, according to a Greater Wellington Regional Council scientist.

The marine plant species, called Phormidium, produces a toxin as deadly as cobra venom. It grows in mats on river stones, but can detach and float to the edge.

FAIRFAX NZ

Dog owner Dale Wilkinson and remaining basset hounds, Saffron, Urma, whose mother was one of the dogs that died after consuming the deadly algae by the Hutt River, and Alfie. Wilkinson lost pups Sarah and Reg in 2008.

There, drying up in the sunshine, it produces a distinctive earthy or musty smell that is almost irresistible to dogs. A canine who ingests a piece as small as a 50-cent coin can start seizing in minutes and die within half an hour.

READ MORE: Dog dies after contact with algae in Hutt River

Humans who come into contact with it can also suffer serious health risks.

VICTORIA UNIVERSITY

Environmental scientist Mark Heath samples water for Phormidium algae.

Council environmental scientist Mark Heath, who did his Victoria University PhD on the deadly algae, said the weather this summer, with El Nino conditions, was likely to boost the algae's growth.

"If you see a black leathery mat on those river bed rocks, that's to be avoided. They're very distinctive because of the smell they produce: a very deep, earthy odour.

"We're monitoring it once a week and we encourage everyone to check our Summer Check website, that has the current information on what the risk is."

Heath's studies showed the algae seemed to prefer water with low phosphorus levels as, unlike other water plants, they can ingest this essential mineral for life from the sediment on the river bottom.

It was likely that as efforts to clean up rivers and waterways - such as building water treatment plants and creating estuaries - reduced the level of phosphorus in the water, the prevalence of Phormidium and its risks to dogs was growing.

"We tend to believe that the occurrence of [Phormidium] is increasing around the country."

But the good news from Heath's research was that as work tackling nutrient pollution increased, the deadly algae was expected to become rarer.

"There's no easy solution ... All the things we can do to reduce our nutrients going into rivers, things like riparian planting. It's got to be a long-term and pragmatic approach."

Heath said scientists only had theories about why the algae made the deadly toxin, which it had been producing for billions of years, long before mammals were around to die from it. "It may be a reaction to stress ... it might be a communication signal between the algae themselves."

DOUBLE DOG DEATHS

In 2008, Lower Hutt resident Dale Wilkinson lost two of his dogs after the group of five basset hounds had a trip to the Hutt River.

Two went in the water, and three had stayed on the river's edge. "We always used to run them down there."

The pups were all fine when they got home, but about half an hour later 10-year-old Sarah was seriously ill, her mouth foaming.

"It was pretty bad. I went out to let them out after being fed and found one of them lying on the ground barely breathing ... The [dog's] heart just slows down and then stops."

The Wilkinsons rushed Sarah to the after-hours vet, but she was dead by the time they arrived. "We didn't think about the other ones."

But when they arrived home, a younger dog, Reg, was lying dead in his kennel. "To lose two of them at once was just unbelievable. They'd been with us for a long time."

Their regular vet checked the surviving dogs and performed an autopsy on Reg and found what was thought to be the Phormidium algae in his stomach.

Neither of the dead dogs had been swimming, and both deaths happened without warning. "It was probably an hour and a half after they'd eaten it."

The Wilkinsons now avoided the Hutt River, especially in summer, and warned people to keep their dogs away from areas that smelt like compost.