Could brown seaweed play a crucial role in preventing the detrimental effects of climate change? (Image Source: Matthew Dogget/IMAS)
By Anna Day | @anna_day_
World leaders will view excerpts from environmental documentary 2040 at tomorrow’s Climate Action Summit, hosted by the UN; with one of the film’s ideas posing intriguing implications for Australia.
Among other tangible climate change initiatives, 2040, directed and written by award-winning Australian filmmaker Damon Gameau, explores how brown seaweed could play a role in regenerating our oceans, improving food security, and pulling tonnes of carbon out of our atmosphere each year.
A lot of brown seaweed’s humble yet remarkable potential has to do with its growth rate: brown seaweed (also known as giant kelp) grows an incredible 50cm per day.
In the film, director Gameau joins Dr Brian Von Herzen, founder of the Climate Foundation, on a boat trip to a kelp forest to learn about the foundation’s plan to restore marine ecosystems through marine permaculture.
Dr Von Herzen explains that as well as restoring habitats for marine species, the seaweed’s rapid growth could sequester thousands of tonnes of carbon per square kilometre per year.
Coastal Environments lecturer at UniSA, Professor Craig Styan said that while creating any forest to hold carbon is a good idea, the amount of CO2 sequestered by seaweed permaculture would depend on the standing stock held in the water.
“Once the algae are processed into food or other consumables, then much of the carbon will be released again,” Dr Styan said.
Dr Styan said to make a difference on the scale suggested in the 2040 documentary, large areas of offshore waters would need to be taken up with algal culture.
Dr Von Herzen also suggests on 2040 that the pacific oceans are the ideal place for large-scale, offshore permaculture platforms.
“Between Australia and the United States, there’s a hundred million square kilometres of ocean desert that is amenable to Marine Permaculture,” Dr Von Herzen said in 2040.
While Tim Flannery, author of Sunlight and Seaweed: An argument for How to Feed, Power and Clean Up the World, wrote in The Conversation that potential entrepreneurs don’t need to be concerned with “bureaucratic red tape”, as “much of the mid-oceans remain a global commons”, Dr Styan has reservations.
“Setting aside the governance issues for anything in international waters, I reckon this [large scale aquaculture in the pacific] is unlikely in the short term for a couple of basic reasons,” Dr Styan said.
“First, we really don’t have much expertise in doing aquaculture in offshore areas, which are far more exposed and difficult to work in than near shore.”
“We do know how to do things offshore for oil and gas development, so possibly some of that know-how could be transferred. But I think a bigger problem will be the economics—anything offshore is expensive to manage and to get back to markets onshore.
“If the key idea is to produce algae for something of relatively low value like food (or feed for animals or even biofuels), algal is largely water and so heavy and expensive to transport, and there are far cheaper ways to produce equivalent biomass onshore.
“There are some high-value products that algae can produce uniquely (e.g. some pharmaceuticals or nutraceuticals), but if you produced these in large volumes, the high price they now attract would crash.”
While the scale of such artificial seaweed farms is something we likely wouldn’t see beyond 2040 or if at all, Dr Styan said naturally occurring algal forests shouldn’t be overlooked for their role in sequestering significant amounts of CO2.
“Most importantly, we need to make sure we don’t lose the natural algal forests in nearshore systems through habitat modification or bad fishing practices or pollution,” he said.
“[We need to] maintain the capacity of the algae we already have to fix significant amounts of carbon naturally.”
A joint research project, conducted by the Climate Foundation and the University of Tasmania, has already seen scientists from the University of Tasmania breeding spores from depleted giant kelp populations in the lab to prepare for planting in the field.
This paves the way for Australia’s first regenerative marine permaculture test platform, which would be launched in Storm Bay, Tasmania, to restore the area’s degraded giant kelp forests.
According to Get Stem, more than 95 per cent of the rich and dense giant kelp forests that were iconic to Tasmania’s East Coast have been lost as a result of climate change.
“The primary driver of the decline in our giant kelp forests has been the extension of the East Australian Current into Tasmanian waters as the ocean climate in eastern Tasmania warmed,” Professor Craig Johnson, one of the project’s principal investigators, told Get Stem.
“…Our study aims to establish whether there’s any chance of restoring these important marine communities by identifying individual giant kelp plants that may be genetically better adapted to warmer sea temperatures.”
Individuals and local authorities can also play an essential role in preserving our natural sources of algae, including addressing urban runoff and pollution in our oceans.
Irrespective of whether it will help solve our planet’s greenhouse gas crisis, algal aquaculture has a range of other positive effects locally or inshore.
For example, by installing algal aquaculture next to commercial fish farms, the seaweed can collect surplus nutrients like fish wastes and uneaten food that would otherwise pollute the waters.
“Increasingly, people are looking at integrated aquaculture systems (essentially permaculture), where algae grown nearby can help suck up some of these nutrients and in some cases be used to then supplement fish food, leading to much more sustainable systems,” Dr Styan said.
Seaweed can also provide an important food source for humans.
While North-East Asian countries like China, Korea and Japan have been eating varieties of seaweed for centuries, the West has only recently caught onto its benefits.
Dr Styan said that while most seaweed farming for human consumption occurs inshore, if we were to increase the amount of food we get from ocean aquaculture, then algae, and possibly oysters and mussels that feed on algae, are some of the few species we can sustainability expand global production for over the next few decades.
“Unfortunately, production of the sorts of aquaculture species that we like to eat in Australia, like Atlantic salmon or prawns, can’t really grow much because these use some amount of other fish as feed in their production and we already take about as many fish as we can from wild stocks,” he said.
“It’s essentially the same energetic argument as one reason for vegetarianism—a lot of people can eat things lower down the food chain fairly sustainably, but the further up the food chain you eat, the more energy, space, resources are needed to produce your food and the fewer people our planet can sustain.”
So while seaweed might not be the one-stop fix to offsetting the carbon crisis in our oceans, it does offer a raft of potential sustainable solutions for our future.