Study finds seaweed quadruples fish immunity

The study found that a small amount of a pink seaweed called Asparagopsis, when added to the diet of rabbitfish, resulted in a four-fold improvement in their innate immune response.

Study finds seaweed quadruples fish immunity
Photo source: USC
May 6, 2021

Scientists at the University of the Sunshine Coast (USC) in Australia found they can quadruple the immune response of farmed fish by adding powdered seaweed to their diet. The study found that a small amount of a pink seaweed called Asparagopsis, when added to the diet of rabbitfish, resulted in a four-fold improvement in their innate immune response. The same seaweed has been found to reduce methane emissions in cows.

“The seaweed quadrupled the immunity of the rabbitfish, meaning they were more likely to be resistant to pathogens down the road. We also showed that this seaweed is stronger than four immunostimulants currently used in aquaculture,” Valentin Thépot said, PhD candidate who led the study. “This means that a seaweed-based feed additive could one day replace the use of veterinary drugs or antibiotics in aquaculture that can be detrimental to the environment, to animals and even to us as consumers.”

Thépot said disease costs the global aquaculture sector more than $6 billion each year, with some industries entirely wiped out by outbreaks. Of the 11 seaweeds that the team tested, two others proved promising: Dictyota, which doubled the fishes’ immune response, and Ulva, which almost did the same.

Thépot said fish had similar innate immune responses to poultry, pigs, cattle, and other farm animals, meaning seaweed could offer significant benefits to agriculture globally. “There is no reason that this immunostimulant effect would be limited to just fish. It may be applicable to other agricultural industries, and different species of seaweed may offer other immune or production benefits. There is definitely scope for further research.”

USC patented the process for commercial use, confident in the enormous market potential for natural seaweed additives in Australia and across the world. “While there is an abundant supply of Asparagopsis in the wild in Australia, the Pacific Islands and parts of Europe which have helped kickstart research and development, the wild harvest of seaweed for commercial purposes has its limitations,” Professor Nick Paul said. “There are already several companies in Australia interested in farming Asparagopsis commercially because it has been found to greatly reduce the methane emissions of cows and other ruminants when they eat it. This new discovery gives all the startup aquaculture companies another market opportunity for the seaweed they produce.”

“The challenge now is to pinpoint the culture strategies that improve seaweed production so we can accelerate industry growth in Australia. We are doing this part of the work with genomics, funded by the Australian Research Council Discovery Program, to better understand the genes involved and select the best strains,” Paul said.

USC’s Seaweed Research Group has previously helped establish seaweed industries in developing countries such as Indonesia and Samoa and expects the successes there could be replicated at scale in Australia and contribute to the country’s post-COVID economic recovery.

The study was led by PhD candidate Valentin Thépot, supervised by Professor Nick Paul, Alexandra Campbell and Michael Rimmer from the USC Seaweed Research Group and partly supported by the Australian Centre for International Agricultural Research project on accelerating the development of finfish mariculture.

Check out the study here.