Sea lettuce trial could hold key to cleaning up New Zealand's dirty waterways

It causes a stink on beaches and in harbours, but sea lettuce could hold the key to cleaning up New Zealand's dirty waterways.

For the first time, researchers are growing the seaweed on land - to rescue a nearby estuary.

Thousands of floating blobs of seaweed are growing - not in their natural environment, but in vast tubs in a science laboratory. And it’ll soon be put to good use in our waterways.

"Is it exciting to get this project underway? Oh it’s super exciting!," says University of Waikato senior research fellow Dr Marie Magnusson.

With a recent funding boost through the Ministry for Primary Industries (MPI), this station will be re-created on the Coromandel, acting like a water treatment plan for the Waihou River Estuary.

The seaweed essentially soaks up and filters out excess nitrogen and phosphorus meaning cleaner water will flow back into the river.

"There’s a large problem in New Zealand all around the country really with high nitrogen concentrations both in freshwater and down into the groundwater," Dr Magnusson says.

When scaled up, a plant like this could produce up to 50 tonnes of sea lettuce per hectare.

That’s music to the ears of seaweed innovation company AgriSea, working with the University of Waikato on the two-year project.

"It’s really neat. Seaweed is such an exciting space, it’s a sunrise industry here in New Zealand," AgriSea managing director Tane Bradley says.

When the sea lettuce is ready for harvest, the opportunities are vast - from skincare products to soil treatment, with many avenues still to explore.

"It’s got some really potent bioactives that are really interesting for cosmetics, and nutrition and nutraceuticals. It’s got quite high protein," AgriSea science, research and development general manager Clare Bradley says.

If the trial is successful, sea lettuce could be grown near waterways right across the country.

"There's a few bits and pieces that still need to be done but this project will answer a lot of those questions," Dr Magnusson says.

Tidying up our rivers and creating business opportunities while doing it.