Algae futures

Algae

The term ‘algae’ refers to a broad variety of photosynthetic eukaryotic organisms that inhabit both marine and freshwater aquatic ecosystems, within the photic zone.

This definition includes both macroalgae (multicellular plant-like organisms commonly referred to as seaweed) and microalgae (microscopic, typically unicellular organisms that comprise phytoplankton).

The standard categorization of algae establishes seven different divisions: chlorophyta (green algae), phaeophyta (brown algae), rhodophyta (red algae), pyrrophyta (dinoflagelates), chrysophita (diatoms), euglenophyta (euglenoids) and glaucophyte (glaucophytes).

Given their ability to perform photosynthesis, analogous to that of algae, cyanobacteria are often also included in the taxonomy of algae as ‘green-blue algae’ (Schoch et al., 2020), despite being prokaryotic organisms.

The vast variety of species that fall under the common categorization as algae allows for a similarly ample range of products and applications, including medical products, cosmetics, pigments, energy generation, environmental remediation, etc. (Sharma et al., 2016).

futures

Currently, macroalgae are cultivated all throughout the world for human consumption, as they constitute an integral part of many cuisines, but the consumption and farming of seaweed is dominated by countries in East Asia: “The major seaweed producing nations are China (47.9%) and Indonesia (38.7%) followed by the Philippines (4.7%) and the Republic of Korea (4.5%)” (Food and Agriculture Organization, 2018, cited in Kelly, 2020).

Some of the most notable species of edible algae are:

• Red algae: Nori (Porphyra and

Pyropia, mainly P. yezonesis and P. tenera), agar-agar (extracted from

Gracilaria and Gelidiaceae), dasima (Saccharina japonica) and guso (Euheuma).

• Green algae: Sea grapes (Caulerpa lentillifera), gutweed (Ulva intestinalis), sea letucce (Ulva spp.) and Chlorella spp., these last being a genus of microalgae commonly used as a supplement.

• Brown algae: Kombu (Laminariaceae), wakame (Undaria pinnatifida), cochayuyo (Durvillaea antarctica) and the Sargassum spp.

• Cyanobacteria: Some species of

the genus Arthrospira, most notably Arthrospira spirulina, also used as a health supplement.

In addition to their traditional consumption, similar to that of conventional vegetables, certain species of algae are cultivated so they can be refined through a series of chemical processes into polysaccharides, namely carrageenan (mainly red algae) and alginate, extracted from brown seaweed (Kelly, 2020), both used as gelling/stabilizing agents in the food, biotechnology, and pharmaceutical industries.

The use of seaweed as a fertilizer is also widespread and well established, with documents of its use as early as the 2nd century, where it was used also as protopackaging and livestock feed (Cotas & Pereira, 2019), and scientific evidence of its positive effects in crops dating back to 1965 (Aitken & Senn, 1965). Seaweed fertilizer is currently available in various formats, from seaweed meal to liquid. More recent research has further explored its capacity to improve the stress tolerance of crops and the quality of the soils not only by being a rich nutrient source, but also as a combination of its effects as a soil conditioner, its osmoprotective qualities, the interaction of the phytohormones present in seaweed with the cellular activity of crops, its capacity for bioremediation of polluted soils, and its positive impact in the microbial composition of the soil (Raghunandan et al., 2019).

Some of the other emerging applications of seaweed, due to their early stages of experimentation, will be further discussed later in this document.

As cited before, the records of historical usage of seaweed for various applications in scattered locations around the globe attest that it is intrinsically a versatile resource that has aided for ages in the

Kunstformen der Natur (1904), a series of botanical drawings of seaweed by German naturalist Ernst Haeckel. Figure 3. 5.

development of techniques for survival (Cotas & Pereira, 2019). Furthermore, for the aforementioned civilizations, seaweed has constituted not only a part of their diet, shelter, clothing, fishing and, overall, material culture, but also a part of their rites, celebrations, and ceremonial activities (Thrustan et al., 2018).

Provided the presence of local varieties with different chemical and mechanical properties around the world, local traditional knowledge consequently becomes a crucial indicator of the potentiality of local species of seaweed for different fields of application (Manly Seaweed Forest Festival, 2021) and, as such, a significant amount of resources have to be invested in re-gaining and keeping alive these forgotten “seaweed cultures” in order to respond to the urgency that the environmental crisis adds to the development of these new bio-based solutions. Its social significance consequently extends beyond mere cultural preservation, and its potentialities to resolve current global affairs as food insecurity (dietary uses, nutritional supplements, fertilizers, polluted soil remediation, livestock feed), freshwater supply and wastewater management (water filtering), energy supply (third generation biofuels), microplastic pollution (bioplastics), health (pharmaceutical applications), etc., are key to address the Sustainable Development Goals adopted by the member countries of the United Nations in 2015 (Sutherland et al., 2021).

Algae thus presents as a promising ingredient for mor sustainable alternative futures (Climate Change Cluster et al., 2021), whose industrial applications and consumer products are yet to be imagined.

Figure 4. Graph extracted from Conceptual Design between Fiction and Reality (2018), Johanna Schmeer.