Meet Michael: Our Seaweed Whisperer
The Fascinating life of Kelp
Michael sits in his office in Namibia thinking about growing seaweed, Macrocystis pyrifera to be precise. Macrocystis is a type of large brown algae, part of the Laminariales family, known more commonly as Giant Kelp. It’s a risky venture, as Macrocystis, has never been farmed at scale before, nor has it ever been farmed in this part of the world before.
Michael is no stranger to Macrocystis – as a Marine Biologist, specialising in Aquaculture and Phycology, he completed his MSc university thesis at the University of Cape Town researching Macrocystis in South Africa.
As the head of Seaweed Sourcing and Propagation at Kelp Blue, it is a big responsibility try to grow Macrocystis from cultures, transfer them from the hatchery to the ocean and grow them to full size in coastal waters known for their strong currents and high winds. But Michael is ready for the challenge.
What is your role at Kelp Blue?
I’m responsible for the Biosystems stream at Kelp Blue. I look after everything to do with growing the kelp, managing the hatchery, as well as monitoring and reporting the growth rates of the kelp and assessing the environmental interactions post-outplanting on the offshore cultivation structure. Basically, the health of the kelp throughout the whole production life-cycle of the algae.
How does Macrocystis grow?
The life of Macrocystis is quite incredible. Similar to other kelps, it presents a 2-phase life-cycle – the sporophyte and gametophyte phase. The sporophyte is the macroscopic kelp we see in the ocean today and the gametophyte is a near-microscopic form of organism, tiny clusters of cells that are the most important player when growing kelp. The gametophyte reproduces by sexual reproduction. The male gametophyte produces sperm, and the female produces eggs, and their fusion creates a zygote that divides continually to form a sporophyte and will eventually grow into long, leafy plant-like vegetation. Once sporophytes mature into adults, they release spores which divide and produce more gametophytes. The union of 2 of these gametophytes (male and female) during fertilization effectively produces a new sporophyte and the life cycle goes on.
Images of young sporophytes produced by gametophytes- the sporophyte is the multicellular leaf-like structure (many in the left image and one in the centre of the right image) and the gametophyte is the small structure from which the sporophyte grows from post-fertilisation
Where did the gametophytes originally come from?
We received our gametophytes approximately 2 months ago from a seaweed seedbank in the Netherlands called Hortimare- a company that specialises in breeding and propagating commercially farmed seaweed species. They were originally collected from different populations in the Falkland Islands and South Africa and were being stored in the Netherlands before being transferred to and incubated here in Namibia. We collaborate closely with Hortimare to share knowledge for the successful cultivation of our cultures. Additionally, they shipped us our red-light incubators which allows us to store the gametophytes alive and propagating in a suspended state, unable to produce sperms and eggs until we are ready. Hortimare also holds back-up cultures in their culture bank, for risk management and research purposes.
How do they get from microscopic cultures to a large plant growing out at sea?
Once we are ready to hit the grow-out phase, we subject the gametophytes to white light, which starts the production phase, called induction. After 2-3 weeks, the female gametophyte will produce eggs that will be fertilised by sperms released by the male gametophyte and sporophytes will form. During this period, we closely monitor their development under microscope. When they are large enough, they can be transferred to a substrate – this is basically a container which holds a PVC tube wrapped with twine. The sporophytes are applied to the twine, and here they will latch on and start to grow until they are ready to be transferred to the ocean for ‘out-planting’ on the rig. It is quite a manual process and there are a huge number of risk factors along the way, so the process is conducted in a very meticulous and hygienic manner. Our aim is to have one successful plant survive and grow to maturity on each small segment of twine attached to the array, ready for harvesting.
Under good growing conditions, Macrocystis can grow anywhere from 10cm to 35cm per day (and some literature reporting even higher growth rates than this!). The larger it becomes the more biomass it is able to generate. However, the process to maturity is very challenging given Macrocystis has never been farmed at this scale before, nor does it grow natively in Namibia. There is the risk of contamination in the hatchery, risks when transporting the sporophytes to the ocean, the ocean itself – sea temperature, currents, wind; so, it is important we put in maximum effort to ensure our kelp thrives and is able to provide the ecosystems benefits associated with kelp forests. The pilot will begin toward the end of Q1 2022 on a 1 hectare plot, on a specially engineered structure 15m below the water’s surface.
“I don’t believe the separation of humans and the environment is the way to go. I know we can develop a healthy regenerative system of aquaculture that benefits humans, while at the same time making a concerted effort to rehabilitate coastal areas and address some of our greater environmental challenges. If all things go well, in 10 – 12 months when we have giant kelps, we’ll know whether these aspirations will be realised, if not, we keep trying.”
