Scientists put seaweed plaguing Tauranga harbour to good use

February 2, 2020

Scientists are working hard to develop a practical use for the smelly seaweed.

Tauranga's harbour is plagued by seaweed and it's just one of many that's seeing an increase in sea lettuce. Fertiliser run-off is fueling the problem down the coast in the Maketū Estuary too.

New Zealand scientists are developing ways for the sea lettuce to be put to good use.

"We do see a build-up of sea lettuce in Maketū as well as down the road in Tauranga, and some of our other estuaries, so this is largely due to too much nutrients," marine scientist Shari Gallop told 1 NEWS.

Sea lettuce smothers other marine species, but the lab is exploring practical uses for seaweed. 

"Basically we're working on a method for fementing green seaweed called algae," Waikato University's Krystal Ryan says.

They're exploring how it could be used to create a plant feed, which would leach fewer nutrients to the sea by using three different fermenting processes.

"One with a scoby, one with a rice broth and one with an in-house plus supplement," said Ms Ryan.

The product helps to grow sacrificial tomato plants. 

The plants are then dissected with their roots removed, measured, weighed and recorded. 

"We hope to find a way that's able to utilise algae that is so easy and accessible for everyone so that we don't have to have a chemical process," said Ms Ryan.

They're also cultivating seaweed on land.

"We can actually have systems set up where you can pump nutrient rich water from the environment the algae will actually take up the nitrogen and phosphorous from the polluted waters, and once you harvest the algae out from the land-based systems you have nice clean biomass as a regular supply and clean water," Seaweed Aqua Culture programme leader Marie Magusson says.

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