Researchers at the University of Bergen and Uni Research of Norway hatched an idea that sounds too good to be true: a common marine species that consumes microorganisms and can be converted into much-needed feed for salmon or a combustible biofuel.

The crop is named Tunicates (ciona intestinalis) an unexpected source of such rich potential.  The species is the starting point for a research-based innovation project being carried out by researchers and innovation specialists in Bergen.  Tunicates can be cultivated in vast amounts: producing 200 kg (almost 100 pounds) per square meter of ocean surface area.

Norwegian fjords could sustain tunicate farms that produce 100 times more protein by surface area than any land-based protein cultivation. Pictured are tunicates raised at a research facility in Øygarden, Norway.  Image Credit: Photo by Bård Amundsen, University of Bergen  Click image for the largest view.

Norwegian fjords could sustain tunicate farms that produce 100 times more protein by surface area than any land-based protein cultivation. Pictured are tunicates raised at a research facility in Øygarden, Norway. Image Credit: Photo by Bård Amundsen, University of Bergen.  Click image for the largest view.

The yellowish, slimy growth that the seagoing among us have come across on ropes that have laid in seawater is the marine organism known as tunicates.  Tunicates are basically living filter tubes that suck bacteria and other microorganisms into one end and excrete purified water out the other end. This is how tunicates feed – at the very bottom of the food chain and without competing directly with fish or other marine animals higher up in the chain. At the same time tunicates clean the fjords and coastal areas.

The fact that tunicates are also the only animals that produce cellulose – and that they are rich in omega-3 fatty acids – makes them a potential alternative for bioethanol and as a feed ingredient for farmed fish.

Found in every ocean, tunicates grow very quickly and year-round and they particularly thrive in cold, nutrient-rich waters such as those around the quays and coastal rock slopes of Western Norway.  Since there are no marine predators feeding on tunicates, some 2 500 to 10 000 individuals can grow undisturbed in a square meter of ocean surface area.

Other than the Japanese and Koreans, who eat tunicates, no one has paid them much attention until now.

For the first time ever, tunicates are being cultivated experimentally at a pilot facility in Øygarden, a small island community near Bergen.  The production method resembles the cultivation of mussels. At a facility in a small finger of a fjord, long plastic sheets are anchored to the seabed and held vertical by buoys. Between these sheets flows seawater teeming with the microorganisms tunicates need.

The tunicate is the only animal known to produce cellulose, with which it constructs its body wall, called the mantle.

Breaking down cellulose yields sugars that can be used to produce the fuel bioethanol. Much of the world’s bioethanol currently comes from corn, a controversial source since some people still believe the field corn crop could be used to feed people instead.

One alternative being thoroughly researched is to produce bioethanol from the cellulose in forest-based biomass. But this is not unproblematic either, since the biopolymer lignin contained in wood is valuable in many other applications. Tunicate cellulose would be a less controversial source because it does not contain lignin.

Even more attractive than biofuel production is the use of tunicates in feed for salmon and other farmed fish. Norway is the world’s largest producer of salmon feed, and there is a huge demand for more marine proteins as feed ingredients, but the limit has already been reached in industrialized fishing.

One major challenge facing feed producers is to produce salmon feed containing omega-3 fatty acids, which the fish need but do not generate. The bulk of omega-3 in salmon feed presently comes from the fisheries industry. Dried tunicates contain 60 per cent protein and are rich in omega-3. Perhaps just as importantly, salmon find them tasty as well.

Protein production from marine cultivation of tunicates has 100 times the potential per square meter than any land-based protein cultivation. Moreover, the food that tunicates need is readily available in the form of vast amounts of microorganisms in nutrient-rich marine waters.

The project manager Christofer Troedsson of the University of Bergen’s Department of Biology explains the primary problem with, “Our single greatest challenge is cultivating enough biomass per square meter to make operations profitable. We anticipate a crop of 100 to 200 kilograms per square meter, which is an extremely high yield. But that is what is needed for profitability because the price per kilo is so low.”

The Bergen-based researchers have achieved this production target at their small-scale facility, and the mathematical models they have run make them optimistic that a similar production level is possible with large-scale tunicate farms.  So far there is no testing at commercial scale.

The second problem continued Troedssen is, “The second major challenge we face is how much water we can squeeze out of the tunicates. Their body mass is 95 per cent water. To sell the product we have to be able to remove at least 90 per cent and preferably 95 per cent of that water by mechanical pressing.”

“On an isolated basis we have managed to mechanically press out 97 per cent of the water. Now we must try to carry out that process efficiently on board the harvesting boats, while at the same time pulling several metric tons of tunicates per hour out of the sea. Thus production volume and water separation are the two critical factors that must be successfully addressed if tunicate cultivation is to be profitable for private companies in today’s market,” concludes Dr Troedsson.

The Research Council of Norway ‘s program Commercializing R&D Results and the technology transfer office Bergen Teknologioverføring (BTO) are investing heavily to scale up tunicate production allocating NOK 8.7 million in funding to the tunicate project set to run through 2014.

That’s just enough information to generate a bit of curiosity.  Maybe even a trial tasting.  Maybe.


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1 Comment so far

  1. Using Tunicates for Fish Feed and Biofuels | Thinking Machine Blog on July 3, 2013 5:47 AM

    [...] H/T New Energy and Fuel. [...]

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