Asparagopsis taxiformis

''Asparagopsis taxiformis'', (red sea plume or limu kohu) formerly ''A. sanfordiana'', is a species of red algae, with cosmopolitan distribution in tropical to warm temperate waters. Researchers have demonstrated that feeding ruminants a diet containing 0.2% ''A. taxiformis'' seaweed reduced their methane emissions by nearly 99 percent.

Lifecycle

Like many red algae, ''A. taxiformis'' has a haplodiplophasic lifecycle, with each phase morphologically distinct. The species' haploid stage was initially described as ''Falkenbergia'' ''hillebrandii'' (Bornet) Falkenberg 1901 because it was thought to be a separate species. The resources which are needed for the red algae to continue to grow is very complicated.

Culinary uses

''Asparagopsis'' is one of the most popular types of ''limu''. in the cuisine of Hawaii, it is principally a condiment. It is known as ''Limu kohu'' in the Hawaiian language, meaning "pleasing seaweed". ''Limu kohu'' has a bitter taste, somewhat reminiscent of iodine, and is a traditional ingredient in ''poke''.

The essential oil of ''limu kohu'' is 80% bromoform (tri-bromo-methane) by weight. It also includes many other bromine- and iodine-containing organic compounds.

Methane emissions reduction in ruminants

In 2014, researchers at CSIRO and James Cook University demonstrated that feeding ruminants a diet containing one to two percent red seaweed reduced their methane emissions by over 90 percent. Of 20 types of seaweed tested, ''A. taxiformis'' showed the most promise, with nearly 99 percent effectiveness.

The findings spurred further investigation into its effects on ruminant animal enteric methane production. In 2016, the same team showed that 2-5% of seaweed biomass effectively reduced production by 98-100% in vitro and, in a separate study, identified the bioactives in ''A. taxiformis''. While dichloromethane extract was the most potent bioactive, reducing methane production by 79%, bromoform and dibromochloromethane had the highest activity inhibiting methane production, and only bromoform is present in sufficient quantities to be effective. In 2020, they showed that a 0.2% addition of ''A. taxiformis'' to cattle’s feed reduced the livestock’s methane emissions by over 98%. In 2021, a team from UC Davis found that additions of 0.25% and 0.5% reduced cattle’s enteric methane emissions by 69.8% and 80% respectively.

Supply from wild harvest is not expected to be adequate to support broad adoption. Subsequent to the Australian study, CSIRO established FutureFeed Pty Ltd., which holds the global intellectual property (IP) rights for the use of Asparagopsis for livestock feed, with the aim of significantly reducing enteric methane emissions in ruminants. In 2020, FutureFeed won a Food Planet Prize worth $1 million for the research behind its inception.

''A. taxiformis'' has yet to be commercially farmed at scale, but several companies are working towards it as they make the seaweed available to the livestock industry. A research/development initiative called Greener Grazing is seeking to close the life cycle of ''A. taxiformis'' and demonstrate ocean-based grow-out.
A startup out of KTH Royal Institute of Technology, Volta Greentech, and Blue Ocean Barns in Hawaii, are growing ''A. taxiformis'' in vertical, near-shore land-based tanks, using seawater to provide the proper temperature and nutrients.Tatiana Schlossberg (November 27, 2020)
"An unusual snack for cows, a powerful fix for climate; Feeding them seaweed slashes the amount of methane they burp into the atmosphere,"
''The Washington Post''. Symbrosia, from Yale University, is looking to integrate the cultivation with whiteleg shrimp on land, using a patent-pending technology. Another start-up, CH4 Global, has developed energy-efficient EcoParks in Australia and New Zealand to produce ''A. taxiformis'' for use in its solutions for feedlot cattle. CH4 Global has partnered with Clean Seas to grow ''A. taxiformis'' at Arno Bay, Australia, where it uses carbon and nitrogen waste from Clean Seas’ ocean-based fish farms as food for the seaweed.

Volta Greentech, Blue Ocean Barns, Symbrosia and CH4 Global have been backed by venture capital funds.

See also

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*Limu (algae) – Edible plants living under water or near water

References

External links

Edible Limu of HawaiiGreener GrazingiNaturalist
especially for more photos.

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Bonnemaisoniaceae
Algae of Hawaii
Edible algae
Hawaiian cuisine
Edible seaweeds
Emissions reduction
Seaweeds
Red algae genera
Bonnemaisoniales