World Aquaculture Magazine - June 2021

WWW.WA S .ORG • WORLD AQUACULTURE • JUNE 2021 29 from seaweeds were to save the world! Unfortunately, all the hype around big, well-funded projects, such as the Marine Biomass Project of the Gas Research Institute of Chicago, delivered very little. No magic fuel extraction or seaweed-based fuel product went commercial, especially after oil prices decreased in the 1980s. What followed was around 35-40 years of “purgatory” for those wanting to continue to work on seaweeds (academics or entrepreneurs). “Why do you want to spend your time studying these obscure organisms? Last time, they promised us the moon and delivered nothing. You better work on something else!” was the common refrain we heard, until very recently. So, is this déjà vu? Have we learned anything? Will the hype and fantasy bubble burst again in a few years, and will another 40 years of purgatory ensue for another generation of seaweed scientists and entrepreneurs who still believe in the rational development of seaweeds for humanity? Having been among the few preachers in the desert over the last 40 years, we still believe in the key food and product roles and ecosystem services seaweeds can provide, and we can testify that these purgatory periods, between waves of seaweed frenzies, are very difficult to live through. We advocate a much more realistic approach to the development of seaweed aquaculture in its new geographies — one highlighting reasons for optimism, but also recognizing the difficulties and not promising dubious moons —and denouncing claims of miracle cures for society and the environment when we see them. Moreover, these periods of purgatory could be avoided by reducing the rhetoric and sticking to the science. Let’s set the stage by first presenting facts that showwhy seaweeds are, indeed, amazing multi-purpose organisms, which we can use appropriately for our benefit. It is true that seaweeds have diverse properties useful in many applications from the morning (keeping pulp in suspension in your orange juice) to the evening (giving texture to your toothpaste) without you knowing they are present as ingredients/agents. That should not entirely be a surprise. Seaweeds (and algae, in general) are what is called a polyphyletic group, i.e. they are an unnatural grouping with different ancestors and different evolutionary histories. To understand that seaweeds are a mixed bag of organisms with not too much in common we have to go back to the Greeks and the Romans in their early attempts at classifying organisms (what is called taxonomy). When the scientists of that time did not know in which group of organisms to classify a new species, they described them as incertae sedis (of uncertain placement). Over time, a lot of seaweeds ended up in the incertae sedis box, which very much resembles a box of “lost and found” mittens, hats and scarves in a school at the end of the winter; they are disparate with not much in common. The consequences of having a name for a group of organisms with not much in common are at least two-fold: 1) Because of this high biodiversity resulting from unnatural groupings, it is not surprising that seaweeds are the sources of many compounds and have amazing properties for many applications, and 2) having very different life histories as a result of very different evolutionary trajectories, their culture techniques vary widely, from the early stages of spore and gamete cultivation, to their grow-out phases at aquaculture sites, harvesting and processing. Farming green, red or brown seaweeds is not very different from growing chickens, kangaroos or alligators. You better know their biology, ecology, physiology, biochemistry, etc. before trying to cultivate them. Please, do not say that they are the “low-hanging fruits” of aquaculture! If they were so easy to cultivate, they would be cultivated everywhere, but that is not the case. So, there must be something else at play to be a successful seaweed farmer. Until now, seaweeds and other extractive species have been valued only for their biomass, food-trading and ingredient values. They need to be valued also for the ecosystem goods and services they provide. These will increase consumer trust and the social/ political license to operate for the aquaculture industry and give more credibility to the increasingly popular “circular economy and blue bioeconomy” approaches and an even greener approach, the Turquoise Economy and the Turquoise Revolution (Chopin et al. 2010). Among the ecosystem services provided by seaweeds, we can cite (Chopin 2018, 2021a): • Seaweeds are excellent nutrient scrubbers, especially of dissolved nitrogen, phosphorus and carbon. • Within an IMTA system and within an Integrated Coastal Area Management (ICAM) approach, seaweeds can be cultivated without fertilizers and agrochemicals, as the fertilizers are provided by the fed component (finfish). What were previously considered wastes or by-products are then recognized as co-products from one species that can be used as recovered fertilizer and feed resources and energy by another species, considered as additional crops providing economic diversification, while bioremediation of coastal nutrification is also taking place. • Seaweeds do not need to be irrigated as they are already in water. In different parts of the world where access to water is becoming an issue, this is a significant advantage (Jasechko and Perrone 2021). • Seaweed cultivation does not need more arable soil and land transformation (deforestation). • Seaweeds can be used for habitat restoration and refugia for other species (Theuerkauf et al. 2021). • Seaweeds are the aquaculture component providing a net production of oxygen while the other animal and microbial components consume oxygen. • Seaweeds can “sequester” carbon dioxide in a transient manner and contribute to slowing global warming and climate changes. By being harvested, processed, eaten or by decaying, they allow a displacement of carbon to other places and a transformation of the forms in which the carbon is associated, but one cannot talk about permanent sequestration at geological time scales. It is vital to remember the sentence from the famous French chemist and physicist, Antoine-Laurent de Lavoisier (1743-1794), to summarize the law of conservation of mass he developed: “Nothing is lost, nothing is created, everything is transformed.” • By “sequestering” carbon dioxide, seaweeds can also reduce coastal acidification. It is important to understand that coastal acidification is not only a story of carbon dioxide because tremendous nutrification of coastal waters is also one of the major causes of coastal acidification (Wallace et al. 2014). Moreover, we intentionally talk about coastal acidification and not ocean acidification. It is highly ( C O N T I N U E D O N P A G E 3 0 )