If we are to feed people in 2050 we have to do things differently.” – Emer Prof John Bolton sampling in a seaweed raceway on a commercial abalone farm. Photo Mike Stekoll.

As the pressure grows on the world’s arable land, aquaculture must play a bigger role in food production if we are to feed a population of 9.8 billion by 2050, as estimated by the United Nations, says University of Cape Town (UCT) Emeritus Professor John Bolton.

The topic underpinned Bolton’s South African Network for Coastal and Oceanic Research (SANCOR) Gilchrist Memorial Lecture at Nelson Mandela University on 15 November. He received the Gilchrist Memorial Medal last year for his many contributions to marine science.

Bolton is a leading expert on the biology and phylogeography of seaweeds, South African kelp forests, and integrated seaweed–marine animal aquaculture. His lecture was titled “The seaweed revolution: biology, aquaculture, nutrition”.

Emer Prof John Bolton at his Gilchrist Memorial Lecture at Nelson Mandela University. Photo SANCOR.

“There is a growing understanding that if we are to [be able to] feed people in 2050 we have to do things differently, and that the global land area will not be sufficient for food production,” he said.

“Although more than 70% of the globe is sea, it is also becoming clear that aquaculture practices will have to become more sustainable than they currently are.

“We will increasingly need to practise integrated aquaculture, growing organisms that are extractive (Ê»unfedʼ). These include filter feeding molluscs such as mussels and oysters, which eat particles, and seaweeds, which remove dissolved nutrients, both of which are released in large quantities in traditional fed aquaculture.”

“Seaweeds are critical to this future. Global seaweed production is currently almost entirely in East Asia so far but has been growing at 8% per year for the last 30 years.”

Seaweeds are critical to this future.

“Global seaweed production is currently almost entirely in East Asia so far but has been growing at 8% per year for the last 30 years, the fastest growing world food sector.”

Nutrition high, calorie low

Nutritionally, seaweeds as a food are said to contain “everything except calories”.

“They can add a multitude of flavours and textures and are now the basis of dishes in most Michelin-starred restaurants in Europe,” said Bolton.

“There is a rapidly expanding research literature demonstrating a remarkable range of health improvement effects for seaweeds in the human diet.”

He added that the market for seaweeds as “functional foods”, offering more than just standard nutrition, is rapidly expanding in Western countries.

“This includes their benefits as prebiotics, helping to create a healthy gut bacterial flora, and there are many studies linking dietary seaweeds to improvements in animal immune systems.”

As the need for seaweeds as a critical component to improve the sustainability of marine aquaculture is becoming clear, there’s been a large rise in research throughout the world on the development of a “biorefinery model” for dealing with the seaweed production.

“This involves the extraction of a wide variety of products from seaweed biomass, from the high end of the market, such as human food, nutraceuticals [and] cosmetics, to lower-priced commodities such as animal feed, colloids, bioplastics, and even biofuel.”

Growing research

Bolton has published extensively, not only on the seaweeds of South Africa but also of Namibia, Angola, Madagascar, the Éparses Islands of the Mozambique Channel, Kenya, Mauritius and Reunion. For more than 30 years he has served as the principal investigator on almost all seaweed-based National Research Foundation projects.

Though recently retired after 35 years in the Department of Biological Sciences and now a senior research scholar at UCT, he remains actively involved in aquaculture research and postgraduate teaching in the area.

The backdrop to his Gilchrist lecture is the growing appreciation in Europe of his research group’s work on South African seaweed aquaculture.

First, he said, there has been a dramatic increase in research worldwide on the incorporation of seaweeds into marine aquaculture, with several large European projects involving “integrated aquaculture” of seaweeds with marine animals.

His group has carried out a significant body of work into the integration of seaweeds into the local land-based aquaculture of abalone. This provides feed and enables partial water recirculation, and is seen as a pioneer commercial success story of sustainable aquaculture.

Second, in mid-2017 the European Union (EU) and governments of South Africa and Brazil signed the Belem Agreement to extend the large network of marine science projects in the North Atlantic Ocean into the South Atlantic.

“There is now an enormous new opportunity for South African marine scientists to link with EU partners on oceanography, aquaculture and marine biodiversity of the Atlantic Ocean, including specific project calls in the EU Horizon2020 programme,” said Bolton.

Serving aquaculture and seaweeds

Far from slowing down after his retirement, Bolton has travelled far and wide this year in service of aquaculture and seaweed research. He was an international panel member on a review of the environmental science BSc degree at the University of the Seychelles. This invitation came courtesy of former UCT postdoctoral research fellow, and now senior lecturer at that university, Dr Laura Blamey.

He followed this by presenting a keynote address on the seaweed revolution and the problem of naming seaweed species at the inaugural “Seaweed4Health” conference, in Ireland in June. He also attended two conferences in France.

The EU sponsored his trip to Montpellier in August, where he contributed to a panel discussion on new and emerging technologies to service societal needs and new value chains. This was at the joint meeting of the World and European aquaculture societies.

Bolton was then funded by the Brest Metropole to attend the Sea Tech Week conference on marine bioresources in Brittany in October, as an invited plenary panel member. His topic, “To what extent is sustainable aquaculture viable?”, is at the heart of his research.

Commercially viable

Although integrated aquaculture has been discussed for more than 20 years at major conferences, it has not yet become a commercial reality in Europe, Bolton pointed out.

“Aquaculture is an industry and aquaculture operations need to be not only environmentally sustainable but [also] profitable. This has been proved over many years on South African abalone farms which grow the sea lettuce Ulva in abalone effluent to produce feed for the abalone.

“Some farms also use the Ulva to remove harmful ammonia from abalone effluent (bioremediation), enabling partial water recirculation, saving up to 40% on water pumping costs and greatly reducing the ecological footprint of the operation.”

 Bolton’s group has contributed significantly to the development of this system.