Volume 63, Issue 4 - Special issue: Seaweed resources of the world: a 2020 vision. Part 4; Issue editors: Alan T. Critchley, Anicia Hurtado, Leonel Pereira, Melania Cornish, Danilo Largo and Nicholas Paul

The commercial landscape of seaweed use in New Zealand (NZ) has shifted and evolved since it was last reviewed in 2006. One of the largest changes saw the introduction of Macrocystis pyrifera and green-lipped mussel spat (which is landed attached to beach-cast seaweed) into the Quota Management System—the primary tool for commercial fisheries management in NZ. There have also been policy changes around commercial harvesting and farming of Undaria pinnatifida , an introduced brown alga native to Asia. Traditionally, commercial algal utilization has been limited to agar production and beach-cast collection for aquaculture feeds, though demand for seaweed products has increased with a growing Asian population in NZ. The NZ seaweed industry is at an early developmental stage, but it has the potential to offer high quality seaweed stock and value-added products to the world market. The exploration of seaweed farming, the growing demand for seaweed fertilizers and the development of high-value bioactive products such as fucoidan has attracted interest from marine farmers and entrepreneurs. The key to success for the NZ seaweed industry rests in developing high-value products for an export market, from integrated farming, harvesting and processing that can deliver the most value, consume the least energy and generate minimal waste.

The seaweed industry of temperate Southern Africa was last reviewed in 2003. Since then there have been considerable changes. There are three main uses of kelp (mostly Ecklonia maxima , with some Laminaria pallida ) in South Africa. The collection of wash-up for drying and exporting for alginate extraction has drastically reduced to very small amounts in recent years. The boat harvest of fresh kelp for abalone feed in land-based farms has reached a plateau of between 4000 and 5000 t fresh per annum. The diver harvest of E. maxima for agricultural liquid plant growth enhancer shows a constant increase over several years, is still growing, and is currently over 3000 t fresh per annum. The small intertidal collection of Gelidium pristoides as export for agar production has maintained a small, sustainable production of around 100 t dry for many years. Former Gracilaria industries in sheltered bays in both South Africa and Namibia have collapsed, and there is currently no commercial collection. There was commercial raft aquaculture production of Gracilaria in Lüderitz Bay, Namibia for a number of years, but this is no longer practised. Currently, the only commercial seaweed use in Namibia is of L. pallida . Annually, ca. 150 t of fresh wash-up is collected, in Lüderitz, to be used as feed in land-based abalone aquaculture. There are a number of small start-up companies experimenting with seaweed products for cosmetics and nutritional products in both countries, some involving species of Ulva and Porphyra . The former species is a major aquaculture product, with around 2000 t fresh yr –1 being produced in integrated land-based systems with abalone.

Due to its large, exclusive economic zone, India has considerable potential for implementing large-scale cultivation of macroalgae. However, such cultivation requires the availability of, and access to, sites where technical, legal, governmental, and environmental factors are favorable. This review discusses the challenges that have held back the development of seaweed cultivation in India. The review is based on a literature survey and informal discussions with industry-related personnel. It cites the strong need for clear and definitive policies related to access to and use of coastal waters to enable the Indian seaweed industry to reach its full potential. The main challenges that the expansion of macroalgal cultivation in India face are related to legal and regulatory aspects that can be resolved by focusing the policy issues on providing planning tools toward success. In addition, there is a strong need for an adequate bioeconomy that clearly defines the need for marine macroalgal biomass for food, chemicals, and biofuels. Furthermore, the Indian government needs to allocate sufficient funds for accelerating seaweed R&D in areas of seaweed cultivation, harvesting, processing technologies, and their implementation in the local industry.

Traditional kelp farming methods require a high amount of labor and are limited in geographic distribution – occurring mainly in nearshore, sheltered sites. To address growing global demand for sustainable biomass, the continued expansion of kelp cultivation will most likely have to move further offshore. Although many offshore cultivation trials have been done over the last 50 years, few were sufficiently robust to be viable in exposed and deep-water areas. In the North Atlantic Ocean, a Faroese company developed and tested a structural farm design that has survived in open-ocean conditions since 2010. The durable structure has withstood harsh weather events common in the Faroe Islands and thereby presents a potential strategy and method for moving kelp farming further offshore. This paper describes the primary challenges of offshore kelp farming and provides an overview of work previously done. Ultimately, the improved productivity, system survivability and scalability the MacroAlgal Cultivation Rig (Faroe Islands) and the BioArchitecture Lab cultivation grid (Chile) represent state-of-the-art and powerfully transformative strategies to pursue large-scale offshore farming to support mass production of kelp in the near future.

The rising global demand for energy and the decreasing stocks of fossil fuels, combined with environmental problems associated with greenhouse gas emissions, are driving research and development for alternative and renewable sources of energy. Algae have been gaining increasing attention as a potential source of bio-renewable energy because they grow rapidly, and farming them does not, generally, compete for agricultural land use. Previous studies of algal biofuels have focused on microalgae because of their fast growth rate and high lipid content. Here we analyze the multiple merits of biofuel production using macroalgae, with particular reference to their chemical composition, biomass and biofuel productivity, and cost-effectiveness. Compared to microalgae, macroalgae have lower growth rates and energy productivity but higher cost-effectiveness. A biomass productivity of over 73.5 t dry mass ha −1 year −1 with a methane yield of 285 m 3 t −1 dry mass would make electricity production from macroalgae profitable, and this might be achieved using fast-growing macroalgae, such as Ulva . Taking into account the remediation of eutrophication and CO 2 , exploring macroalgae for a renewable bioenergy is of importance and feasible.

Tanzania is endowed with a rich biodiversity of seaweed species that grow naturally in its oligotrophic waters of the Western Indian Ocean. Most of these species are unexploited. Only two red seaweeds Eucheuma and Kappaphycus have been studied for commercial farming and the industrial production is based on these species. Another genus of red seaweed, Gracilaria , has been studied and experimented upon for potential farming while others such as the green Ulva , the red Hypnea and the brown Sargassum have been mentioned as potential species for farming. Farming technology used to cultivate the two commercial species is the shallow water off-bottom technology which is badly affected by the increase in surface seawater temperatures (climate change), causing massive die-backs and decreased seaweed production. Some deeper-water farming technologies have been developed but only tubular nets show promise and have been piloted. A number of opportunities exist in seaweed farming, which can be used to advance the industry. The future of the seaweed industry in Tanzania will depend on using the existing opportunities, including utilising the seaweed species already studied, exploring the potential of other seaweed species for farming, development of deeper-water farming technologies, added-value, and ensuring availability of good quality seed material.

The coast of Peru (3.5–18°S) is one of the most productive marine areas in the world. The updated seaweed checklist reports a total of 260 specific/intraspecific taxa, of which the Rhodophyta show the highest number (185 species), followed by Chlorophyta (41 species) and Phaeophyceae (34 species). Since 2012, an increase in molecular studies has been reported mostly in Rhodophyta, while Chlorophyta and Phaeophyceae have lagged far behind. Utilization of seaweed resources has been based on artisanal collection from natural beds. These are mainly consumed fresh or salt-dried ( Chondracanthus chamissoi and Porphyra/Pyropia species), or exported for polysaccharide extraction ( Lessonia nigrescens , Lessonia trabeculata , Macrocystis pyrifera ). Although some regulations for brown seaweed extraction exist, overexploitation is a constant threat that must be addressed. Biomass from seaweed farms accounts, at most, for only 4% of the total annual landings, and there is a decreasing trend on seaweed aquaculture production since 2012. However, some cultivation projects for C. chamissoi and Porphyra/Pyropia species are currently being undertaken. In addition, recent studies have started to explore new uses of commercial and non-commercial seaweeds. Uncovering the Peruvian seaweed diversity and establishing well sustained culture and management projects are essential for utilizing and preserving the seaweed resources of Peru.

Korea has a long history of utilizing seaweeds, as the country has a high biodiversity of seaweeds. The abundance and composition of seaweed species have changed over the past decades due to climate change and anthropogenic influences. Some species showed a significant extension of their distribution range to the north while some species declined. Some areas have even become barren ground. Korea has put extensive effort into restoring the seaweed resources in these deforested areas. Korea is one of the most advanced countries in the World in terms of seaweed aquaculture. However, the aquacultured species are mostly limited to three genera, Saccharina , Undaria and Pyropia/Porphyra , which represent 96% of the entire seaweed production in the country. Korea has developed highly advanced cultivation technologies as well as various cultivars using breeding and hybridization technologies for these species. There has also been considerable effort in developing environmentally sustainable aquaculture systems using seaweed cultivation (e. g. integrated multi-trophic aquaculture, nutrient bioextraction and biofloc). This study discusses the current status and challenges of the above mentioned topics in detail. In addition, the present study encourages South and North Korean scientists to collaborate in the study of seaweed resources at the border of these two countries.