Researchers at the Scottish Association for Marine Science (SAMS) said they have developed a successful tank-based method for growing the red seaweed variety Palmaria palmata, commonly known as dulse.
Researchers at SAMS in Oban have described "phenomenal" growth rates in the institute’s aquarium, observing a doubling in biomass every week.
P. palmata is consumed as a high-end food product. SAMS said it is 40 times more valuable per tonne than kelp and can be used in food, feed, dyes, cosmetics, and pharmaceuticals. However, the species is difficult to grow and, although it can be found along the Atlantic coast, natural stocks are limited.
SAMS said the industry has also struggled with high mortality rates at the hatchery stage, linked to infestation by disease.
The cultivation method developed at SAMS has sought to overcome challenges in how P. palmata grows. Researchers identified a bottleneck at the hatchery phase, as the species has a short reproductive window and the sexual maturity period of males and females is different, posing challenges for growers to control its life cycle.
Often, a mortality rate of 60 to 70 per cent is seen in spores in the initial hatchery stage.
By rebalancing the microbiome by introducing natural grazers and adopting probiotic methods to limit the spread of disease, microbiologist Dr Frederik De Boever has drastically reduced mortality rates in the P. palmata spores to around 10 per cent.
“The growth is phenomenal,” said Dr De Boever. “We’re growing the seaweed from the spore stage to germlings, which increases resilience, compared with vegetatively cut thalli from established adult seaweeds.
“The spore to germling mortality rate is usually high but in the lab, we have more control over that crucial life stage.”
The demand for red seaweed is increasing but this industry primarily relies on a few seaweed species, mainly cultivated in Asian countries, that are facing threats from increasing incidences of diseases.
The combination of improved hatchery methods and tank-based cultivation has given the research team greater control over the environment, compared with open-sea farming, and a more healthy and pristine biomass with low iodine and metal accumulation. The tank-based method also allows for growing P. palmata all year round.