Here, sea lettuce is grown in tanks containing water that was previously used in the seafood industry. Through this cultivation, they take up nutrients that would otherwise have been discarded. Photo Credit: Sophie Steinhagen
On episode 121 of Reef Therapy, we dove deep into frag tanks: the what, the how, and the why. One big reason many reefers set up frag tanks is to generate income to offset their aquarium expenses. Most of us have extra equipment laying around that enables us to put up a frag tank with minimal expense, so why not? What if there was something that’s easier and faster growing than corals; would you grow that instead? While not really intended for aquarium use, the Chalmers University of Technology in Sweden has been working on making macroalgae a viable source of income and nutrition.
With an ever increasing population, the need for viable food sources continues to grow. Protein is an important part of our diet and much of it comes from meat. But the non-meat eating population is growing at a rapid pace. In the early 2000’s, it was estimated that around 3-5% of the US (similar numbers for most western countries) identified as vegetarians or vegans. More recent surveys put that number around 10%, a 2-3x increase! This number doesn’t include part-time vegetarians such as pescatarians or those who are simply trying to limit their meat consumption, so we can safely assume the number is greater than 10%, creating a larger demand.
So what does this have to do with macroalgae and aquariums? Well, right now your main vegetarian protein sources are soy, pea, and mushroom: land based produce that require watering, pesticides, and fertilizers. Aquatic sources of vegetable proteins, which don’t require pesticides, fertilizers, or as much water, are mostly untapped. As all aquarists know, algae grows quickly and with ease. Very rarely do you encounter anyone complaining about a lack of algae growth in their aquarium.
Depending on the species, macroalgae is comprised of 5-25% of the dried weight as protein. This protein is not only rich in essential amino acids, but also minerals, vitamins (such as vitamin B12), and even omega-3 fatty acids that you’d normally find in fish like salmon. So why hasn’t this source of protein entered the mainstream?
Tank cultivation of sea lettuce, dried sea lettuce and grinding of frozen sea lettuce for protein extraction. Image Credit: Chalmers University of Technology | Kristoffer Stedt, Hanna Harrysson and João Trigo
The researchers at Chalmers are addressing just that and are refining the conditions required for optimal growth and nutrition profile of the macroalgae and concentrating the protein content. They’ve recently discovered a method to concentrate the protein extraction by a multiple of 4-5, resulting in a 70% concentration of protein! While that process has yet to be optimized, they did release a study showing a 3.4 fold increase using their method. While the protein concentration process may be a bit involved, the growing process is not. The Chalmers crew found that using old fish-farm water (nitrate rich) resulted in a better product.
What if we were to substitute aquarium water for the fish-farm water? The researchers set up algae tanks filled with used water to grow out the macroalgae, similar to how we’d normally set up a coral frag tank. One advantage reefers have, though, is the use of refugiums. We already use a myriad of macroalgaes in our refugiums, so it wouldn’t take much to switch over to one of their favoured species: Ulva fenestrata and Ulva intestinalis. Now we’d be using the macroalgaes to filter our aquariums, then monetizing it by selling the excess into the food market. Far fetched? At this point, very, unless you have a massive aquarium (we’re looking at you, our public aquarium friends). But knowing just how many larger coral farms have been spawned from a hobbyist’s basement frag tank makes me think that this isn’t as far a leap as it may initially seem.
For the entrepreneurial reefers out there, if you could cultivate a sustainable food source from your aquarium experience, would you? I think we are going to see explosive growth in this sector of the food industry in the coming years and there’s even medical implications that have yet to be fully explored. And when one (or many) of you venture down this path and strike green gold, don’t forget my credit (and cut)!
