Underwater seaweed forests tipped as next big thing in climate change fight

Tuesday, 27 November 2018

Niwa scientist Dr Wendy Nelson says seaweed farming can help combat climate change.

Farming underwater forests of seaweed could help combat climate change, a Niwa scientist says.

Scientists in the Asia Pacific region have banded together to explore the potential of commercial seaweed farming in reducing global carbon dioxide levels.

Experimental farming of the kelp Ecklonia radiata.

Niwa marine biologist Dr Wendy Nelson said marine organisms, such as seaweed, had not really been factored into climate change calculations until now.

Seaweed had many uses including food, biofuels, pharmaceuticals, polysaccharides, stock feed for land and marine animals, but it could also moderate acidification in the sea, Nelson said.

Underwater shot of the kelp Lessonia variegata.

Nelson-based company Waikaitu harvests wakame seaweed in the Marlborough Sounds and turns it into organic fertiliser.

* 'Gorse of the sea' turned into plant products

* Algal blooms in Marlborough Sounds could be an annual issue for mussel farmers**

Undaria, wakame, seaweed harvested in the Marlborough Sounds by Waikaitu.

In New Zealand, there were about 1000 different types of seaweed and the Marlborough Sounds had great potential for seaweed farming, she said.

'It would have to be in places where there was reasonably good water flow, reasonably good nutrient levels and water exchange.'

Nelson-based company Waikaitu harvested wakame, commonly known as wakame seaweed, in the Marlborough Sounds and turned it into organic fertiliser.

Auckland University had partnered with Waikaitu to work on developing a new technology which aimed to create several new products for the global farming and aquaculture industries. Government had provided a $6.1 million grant towards the project.

Nelson said cars could even run on seaweed, some day.

'Algae-based biofuels are being experimented within USA and other countries right now.'

When people burned fossil fuels, they were taking carbon that had been locked away in reservoirs of the earth for millennia.

In the process of burning it, for example oil or coal, carbon dioxide was released into the atmosphere.

'The oceans have been such an important buffer for our climate and have absorbed a lot of carbon dioxide, but now the oceans have got to a point where they're becoming more and more acidic,' Nelson said.

When plants capture carbon through photosynthesis, they take the carbon dioxide out of the atmosphere.

Planting a forest underwater was an approach that people thought was worth exploring, Nelson said.

Up until very recently, reservoirs of carbon stored in seaweed were not considered in the global carbon budget, Nelson said.

'Could the seaweeds be used for biofuel production, which would remove some of the requirement to dig out more coal or use more fossil fuels?' the study asked.

They found it could. The paper looked at the potential for converting the organic matter of seaweed into biofuel, fuel derived from living matter.

This could reduce the use of fossil fuels and provide renewable alternative fuels.

'It would still be using carbon and cycling carbon, but it wouldn't be digging into those reservoirs.

'It's more of a mitigation rather than a removal.'

The seaweed farms would be drawing down carbon dioxide from the atmosphere, specifically in the ocean.

The paper, which was co-written by Nelson, had been named in the top 250 ground-breaking findings to help tackle climate change by Springer, a US-based academic publisher.

'The value of the paper was to gather the information together and to shine a light on what's possible and what the future might hold if we start exploring it.

'It's not one eureka-type moment, this is more about trying to put material together in front of people to start them thinking.'

Up to this point, climate change had focused on terrestrial, or land-based, systems because they were more tractable, more easily understood and measured, Nelson said.

'The understanding of how carbon is sequestered, or stored away, has not focused yet on marine systems, and marine carbon reserves are not part of international calculations.'

At the moment, there was interest in seaweed aquaculture in New Zealand, although this had not translated into the establishment of major initiatives, she said.

'There's people that are interested in exploring the potential, but it hasn't got underway.'

In other parts of the world, seaweed farming was a major industry, she said.

'The seaweed farms in China, Japan and Korea and increasingly in Indonesia, are huge and they're world-leading in terms of seaweed industry.

'In New Zealand, less so. It's challenging in New Zealand because it depends on what the purpose of the product is for.

'If it's for products, then we have to look for very high-value products if it's going to be for an export market, because we're so distant from market.'

There was preliminary work that still had to be done, 'at the moment, people see opportunity but they don't quite know how to realise it', she said.

'It's not the magic bullet, but it's one of a number of strategies that can be used to improve the health of coastal environments.'