Mixotrophically cultured microalgae increase efficiency in shellfish hatcheries

Marine scientists in Scotland developed a way of creating “designer algae” that could signal a breakthrough in how shellfish larvae can be produced for the aquaculture industry.

Mixotrophically cultured microalgae increase efficiency in shellfish hatcheries
February 2, 2021

The Scottish mussel industry currently produces around 8,000 tons a year using wild larvae and is therefore reliant on a successful spawning year. This method is also a limiting factor in the expansion of the industry, which has the potential to become a major part of Scotland’s economy.

However, scientists at Oban-based Scottish Association for Marine Science (SAMS) have discovered a new way of farming larvae in a hatchery by feeding them so-called “designer algae,” which have been selected and grown in a laboratory for optimal growth. By feeding the algae a diet of organic carbon and exposing them to varying levels of light, scientists can control the growth, size and composition of the algae. This system, because it is controlled and tailored for use as mussel feed, is 6-10 times more efficient than the current production systems used in hatcheries for oysters or other mussel larval species. The method could also change how microalgae are produced for the biotechnology industry.

Joe Penhaul Smith, who developed the process at SAMS, said that “these algae are not genetically modified in any way, but are “designer” in that we can cultivate these species in different ways to control their nutritional profile. We are using their natural evolutionary versatility to control how they grow.”

“The system we’ve developed will have an initial start-up cost, but growing the larvae on the scale required will save the industry money in the long term,” Smith said. “I see parallels with the green lip mussel industry in New Zealand, which benefited from a government-built hatchery at the Cawthorn Institute in the 1990s and this now produces around 30% of the larvae for the industry there.”

The SAMS scientists cultivated a wider range of algal species, which can be used for a variety of purposes. One of the most apparent uses of this technology is in aquaculture feed. There is scope for products such as salmon feed. The newly developed feed combines ratios of three algal species, Tetraselmis and the diatoms Phaeodactylum and Cyclotella.

Check out the studies Bioresource Technology Reports and Aquaculture International.