Marine Permaculture: ocean farming and restoring undersea ecosystems

Rozie Apps
Monday, 7th June 2021

Over the last few years, and especially with David Attenborough's Blue Planet 2, the effects of climate change, plastic pollution and chemical agriculture have reached the mainstream. In PM101 we featured new technology from Dr. Brian Herzen and regenerative ocean farming methods from Bren Smith.

“While Earth has survived radical climactic changes and regenerated following mass extinctions, it’s not the destruction of Earth that we are facing, it’s the destruction of our familiar, natural world and our uniquely rich human culture.

“It may sound frightening, but the scientific evidence is that if we have not taken dramatic action within the next decade, we could face irreversible damage to the natural world and the collapse of our societies.”

David AttenboroughOur Planet

David Attenborough’s Blue Planet 2 brought to the limelight, the effects of climate change, plastic pollution and mainstream agriculture on our seas.

The oceans regulate the temperature of the planet, they provide us with oxygen, they are home to millions of creatures that make up diverse and intricate ecosystems, and they sequester carbon. However, scientists are finding that the oceans are saturated in carbon dioxide. They believe around half of the CO2 produced by humans is absorbed by the oceans, and new research shows this is causing acidification, which affects the lifecycles of most marine organisms, especially plankton, the base layer of the ocean food chain. As well as starting diverse ecosystems, plankton also sequester carbon dioxide from the ocean, and when they die they take it with them to the ocean floor. Whole ecosystems are collapsing as the waters warm and acidify, creating rapidly expanding ocean deserts. 

“In the last ten years alone, the impact of climate change has cost the American economy at least $240 billion a year, and future economic costs within the U.S. borders are pre--dicted to be the second-highest in the world, behind only India.”1

Marine Permaculture Arrays

Dr. Brian Von Herzen from the Climate Foundation has been researching into how to increase plankton blooms, which at times can be so vast they’re seen from space. The increased global temperatures are creating a thickening layer of warm water near the surface, which creates a barrier to the upwelling of nutrients from the colder, lower levels of the ocean, which plankton feed on. Von Herzen and the Climate Foundation have created wave-driven pumps to upwell nutrients and grow plankton in a part of the Pacific Ocean around 100km north of Hawaii that is currently an ocean desert. ‘In just 57 hours after deployment, the system sparked plankton growth. Shortly thereafter, these blooms attracted various species of fish. Two weeks later, a 17 foot long [5m] whale shark was circling the area feeding on plankton that had started blooming.’2


An extension of this work is Von Herzen’s ‘marine permaculture’ in the form of larger floating platforms that use wave energy to restore nutrient upwelling to pre-global warming levels. These lightweight, floating systems, called Marine Permaculture Arrays (MPAs), allow kelp to attach, providing food and habitat for forage fish, which in turn brings in tuna and sharks. These MPAs could provide valuable incomes for ocean communities, who could farm the kelp for food, biofuels and animal feed. The MPAs, made from strong, recycled materials, hang from a surface buoy, with a steel cable linking the buoy to the pumping system at the base of the array. As the buoy falls from the crest of a wave, a valve in the pump opens bringing up deep ocean water. As the buoy rises with a wave, the valve closes, forcing the water into an irrigation tube, and up to the floating platform made of interconnecting tubings, which sits 25m below sea level. Nutrient-dense water is released through the holes in the tubing, fertilising the kelp and attracting plankton. They are able to withstand adverse weather conditions, including hurricanes. The idea is that they will be operational without human intervention for up to three years at a time.

The Climate Foundation have collaborated with the Woods Hole Oceanographic Institution, researching the use of mesoscale cyclones that circulate in the Pacific Ocean. Between 5-50km (1.2-6.2 miles) in diameter, these cyclones, of which there can be hundreds at any give time and last for months, could carry dozens of MPAs through the seas, regenerating ecosystems as they go.

Regenerative Ocean Farming

On a different path, but with a similar outcome, is Bren Smith from Thimble Island Ocean Farm, U.S.. A fisherman come restorative ocean farmer, Bren is growing seaweed and shellfish as a means to provide sustainable, local food whilst sequestering carbon and filtering water. As a fisherman, Bren felt the brunt of the cod stock crash in 1992, which laid off 35,000 fellow Newfoundlanders; the largest layoff in Canadian history.1 Bren and a generation of fishermen went in search of more sustainable ways to feed their country through the oceans. Bren finally found himself at Thimble Island in Connecticut, and began farming oysters. His farm was destroyed in Hurricane Irene and then again, after rebuilding, in Hurricane Sandy. This led Bren to design the 3D ocean farm he has today. Using the vertical columns of the sea, Bren grows four types of shellfish, including oysters that can filter 20-30 gallons of water a day, and native seaweeds, including kelp, the second fastest growing plant on the planet. The design allows for flexibility when surges hit, and the oyster beds can be raised from the ocean floor to prevent them being buried in mud during storms. Bren has always made his living on the seas, and renting 8 hectares (20 acres) of sea has not only given him a profitable business, but his quarry is also regenerating the seascape.

©Stephanie Stroud

Seaweed can process large amounts of nitrogen – nitrogen leaks into the seas from agricultural fertilisers (and contributes more than one trillion pounds of greenhouse gas emissions to the atmosphere globally a year,3 creating acidification, which kills swaths of coral and other ecosystems, leaving ocean deserts. ‘Recent work done by Roger Newell of the University of Maryland shows that healthy oyster habitat can reduce total added nitrogen by up to 20 percent. A three acre oyster farm filters out a nitrogen load equivalent to what is produced by thirty-five coastal inhabitants.’1

The columns of seaweed and shellfish create a buffer against storms as well as acting as artificial reefs, providing habitat, and restoring ecosystems. 


The spools to grow the kelp sit in the white plastic tubes at the hatchery, in ideal conditions for maximum growth ©Greenwave

‘One acre of our farm has the capacity to grow 30 tons of sea vegetables and 250,000 shellfish per acre per year with no inputs, making it one of the most sustainable sources on the planet for food, animal feed and biofuel. Our crops also mitigate climate change through carbon and nitrogen seques-tration, and create barriers that prevent storm surges from wrecking coastal communities.’4

Bren doesn’t own his ocean farm, he owns a process. ‘The goal was protecting, not privatizing, the ocean. As farmers, we need to be the park rangers of the ocean commons and build community support through inclusion and thoughtful design.’1 With it being all underwater, apart from several buoys, the farm is hidden from view. It is open to the public, for swimming and fishing, and Bren even has the local duck hunters on side, as his farm attracts a wide range of wildlife.

Bren’s goal is for multiple ocean farms, all producing fresh ocean vegetables with their own distinct flavours in every region. His aim is for the dinner plate to be based around what the sea can provide for us, rather than what we want it to provide. Salmon and tuna are examples of the traditional foods the ocean used to provide in abundance, but with extreme over fishing and climate change, we need to look at the wide range of sea vegetables and shellfish that are available and able to feed us. ‘A Napa Valley of ocean merroirs, producing ocean vegetables with distinct flavours in every region. Ocean farms embedded into wind farms, harvesting not only wind but also food, fuel and fertilizers.’1

Bren has also set up Greenwave, a charity to support those wanting to ocean farm. He wants to make it an easy and affordable career, with a goal of 500 farms across 10 regions, within five years. ‘I see farms that are climate farms, producing zero-input food while sequestering carbon and rebuilding marine ecosystems.’1

‘If you were to have farms covering 6% of the oceans, you could capture all the carbon that’s currently put out by humanity and feed the planet.’5

Another of the many positives with this style of polyculture farming, is that seaweed can also be used as biofuel and animal feed. ‘If you were to take a network of farms totalling the size of the state of Maine, you can replace all the oil in the United States.’5

Both of these models, and the many projects out there, provide positive solutions where humans work alongside Nature’s systems to provide food, jobs and healthy ecosystems. We can regenerate and repopulate the oceans, help mitigate climate change and create resilient futures for people and planet.

1 Eat Like a Fish by Bren Smith, published by Murdoch Books


Useful links

Rescuing the planet's coral reefs: read the article in back issue PM102, available with all subscriptions:

Climate emergency and climate solutions

Protecting the ecosystems around the globe