Phycological research in the development of the Chinese seaweed industry

The term seaweed industry is employed in a broad sense and includes production both of commercial seaweeds such as Laminaria and Porphyra by phycoculture and of processed seaweed products, such as algin, agar and carrageenan.Before the founding of the People's Republic, China had a very insignificant seaweed industry, producing small quantities of the purple laver Porphyra and the glueweed Gloiopeltis by the primitive rock-cleaning method and the kelps Laminaria and Undaria by the primitive stone-throwing method, both aiming at enhancing the growth of the wild seaweeds. Also, a small quantity of agar was manufactured by the traditional Japanese method of gelling, freezing, thawing and drying the product. The small production was not sufficient to meet the demand of the Chinese people who for ages have appreciated seaweeds and their products for food. Therefore, large quantities of seaweeds and seaweed products had to be imported from various countries, for instance, Eucheuma and Gracilaria from Indonesia and other southeastern Asian countries, Laminaria and agar from Japan, even Porphyra from the USA. Annual Laminaria import from Japan generally amounted to over 10 000 tons and in some years approached 20 000–30 000 tons. Some quantities of the glueweed Gloiopeltis and the vermifuge weed Digenea simplex were exported, mainly to Japan.Since the founding of the People's Republic of China in October, 1949, China has exerted efforts to build up a self-supporting seaweed industry. Now after a lapse of 30-some years, a sizable seaweed industry has been developed. China is now able to produce by phycoculture more than one million tons of fresh seaweeds, including Laminaria, Undaria, Porphyra, Eucheuma, Gracilaria etc. and several thousand tons of seaweed extracts, including algin, agar, carrageenan, mannitol and iodine. At present, China still imports some quantities of seaweeds and seaweed products from various countries but is able to produce sufficient quantities to meet the people's need and even to export some quantities of the seaweeds Laminaria, Undaria and Porphyra and the seaweed products algin and mannitol.At the Tenth International Seaweed Symposium, I presented a paper on the Marine Phycoculture of China, in which I emphasized on the methods of cultivation (Tseng 1981b). Therefore I would like to take this opportunity to supplement the last lecture by presenting a paper on the role of phycological research in the development of China's seaweed industry.     

Cultivation of Gracilaria in outdoor tanks and ponds

This review deals with the major problems of unattached Gracilaria intensive cultivation in outdoor tanks and ponds. These problems are presented through the main variables affecting the Gracilaria annual yield and the updated solutions evolved. The physical variables include tank and pond structure, seawater characteristics such as velocity, agitation practice, exchange rate, and salinity, light characteristics such as quantity and quality, and temperature modelling. The chemical variables include nutrient composition and regime of application, and inorganic carbon supply with the pH changes involved. The biological variables include seaweed density, epiphyte competition, grazer damage, bacterial disintegration, integrated mariculture and strain selection. The experience gained in the Israeli research on Gracilaria cultivation is discussed in view of other Gracilaria and seaweed intensive cultivation research.     

Cultivation of seaweed Gracilaria lemaneiformis enhanced biodiversity in a eukaryotic plankton community as revealed via metagenomic analyses

Plankton diversity reflects the quality and health of waters and should be monitored as a critical feature of marine ecosystems. This study applied a pair of 28S rRNA gene‐specific primers and pyrosequencing to assess the effects of large‐scale cultivation of the seaweed Gracilaria lemaneiformis on the biodiversity of eukaryotic plankton community in the coastal water of Guangdong, China. With 1 million sequences (2,221 operational taxonomic units [OTUs]) obtained from 51 samples, we found that the biodiversity of eukaryotic plankton community was significantly higher in the seaweed cultivation area than that in the nearby control area as reflected in OTU richness, evenness (Shannon–Wiener index) and dominance (Simpson index) for total plankton community and its four subcategories when Gracilaria biomass reached the maximum, while no such a significant difference was observed before seaweed inoculation. Our laboratory experiment using an artificial phytoplankton community of nine species observed the same effects of Gracilaria exposure. Principal component analysis and principal coordinates analysis showed the plankton community structure in cultivation area markedly differed from the control area when Gracilaria biomass reached its maximum. Redundancy analysis showed that G. lemaneiformis was the critical factor in controlling the dynamics of eukaryotic plankton communities in the studied coastal ecosystem. Our results explicitly demonstrated G. lemaneiformis cultivation could enhance biodiversity of plankton community via allelopathy, which prevents one or several plankton species from blooming and consequently maintains a relatively higher biodiversity. Our study provided further support for using large‐scale G. lemaneiformis cultivation as an effective approach for improving costal ecosystem health.     

Saldanha Bay,South Africa: recovery of Gracilaria verrucosa (Gracilariales,Rhodophyta)

Since World War II the greater Saldanha Bay lagoon system, South Africa, has been an important Gracilaria producer. Two agar factories, built in the 1960's, used Gracilaria from Saldanha Bay as their raw material. In the early 1970's the industry was destroyed as a result of dredging and marine construction operations to establish a harbor in the bay for loading ore. These environmental changes destroyed stocks and prevented the previously significant beachings of the seaweed from occurring. After a few years of no or very low commercial production, the resource slowly started to recover. The size of Gracilaria drifts increased over the following eight years to approximately one-third of the original output. This trend seems to continue. Although the stocks and resultant drifts are unlikely to recover fully to their original quantity, current production is already sufficient to ensure re-establishment of a seaweed industry in Saldanha Bay. This could have considerable socio-economic impact on the area.     

Seaweed production: overview of the global state of exploitation,farming and emerging research activity

ABSTRACT

The use of seaweeds has a long history, as does the cultivation of a select and relatively small group of species. This review presents several aspects of seaweed production, such as an update on the volumes of seaweeds produced globally by both extraction from natural beds and cultivation. We discuss uses, production trends and economic analysis. We also focus on what is viewed as the huge potential for growing industrial-scale volumes of seaweeds to provide sufficient, sustainable biomass to be processed into a multitude of products to benefit humankind. The biorefinery approach is proposed as a sustainable strategy to achieve this goal. There are many different technologies available to produce seaweed, but optimization and more efficient developments are still required. We conclude that there are some fundamental and very significant hurdles yet to overcome in order to achieve the potential contributions that seaweed cultivation may provide the world. There are critical aspects, such as improving the value of seaweed biomass, along with a proper consideration of the ecosystem services that seaweed farming can provide, e.g. a reduction in coastal nutrient loads. Additional considerations are environmental risks associated with climate change, pathogens, epibionts and grazers, as well as the preservation of the genetic diversity of cultivated seaweeds. Importantly, we provide an outline for future needs in the anticipation that phycologists around the world will rise to the challenge, such that the potential to be derived from seaweed biomass becomes a reality.     

Prospects and challenges for industrial production of seaweed bioactives

Large‐scale seaweed cultivation has been instrumental in globalizing the seaweed industry since the 1950s. The domestication of seaweed cultivars (begun in the 1940s) ended the reliance on natural cycles of raw material availability for some species, with efforts driven by consumer demands that far exceeded the available supplies. Currently, seaweed cultivation is unrivaled in mariculture with 94% of annual seaweed biomass utilized globally being derived from cultivated sources. In the last decade, research has confirmed seaweeds as rich sources of potentially valuable, health‐promoting compounds. Most existing seaweed cultivars and current cultivation techniques have been developed for producing commoditized biomass, and may not necessarily be optimized for the production of valuable bioactive compounds. The future of the seaweed industry will include the development of high value markets for functional foods, cosmeceuticals, nutraceuticals, and pharmaceuticals. Entry into these markets will require a level of standardization, efficacy, and traceability that has not previously been demanded of seaweed products. Both internal concentrations and composition of bioactive compounds can fluctuate seasonally, geographically, bathymetrically, and according to genetic variability even within individual species, especially where life history stages can be important. History shows that successful expansion of seaweed products into new markets requires the cultivation of domesticated seaweed cultivars. Demands of an evolving new industry based upon efficacy and standardization will require the selection of improved cultivars, the domestication of new species, and a refinement of existing cultivation techniques to improve quality control and traceability of products.     

Cultivation and utilisation of red seaweeds in the Western Indian Ocean (WIO) Region

Seaweed farming in the Western Indian Ocean (WIO) Region is carried out in a number of countries, most of them farming Eucheuma denticulatum, Kappaphycus alvarezii and Kappaphycus striatum. These species are farmed mostly in Tanzania with limited production in Madagascar, Mozambique and Kenya; current production (2012) stands at 15,966 t (dry weight) year^?1 of Eucheuma and Kappaphycus, valued at US$ 4.2 million with 95 % of this tonnage coming from Tanzania. Other countries in the region have limited or no seaweed production owing to problems of epiphytes, ice ice and markets. The problem of epiphytes coupled with ice ice that WIO countries are facing causes die-off of Kappaphycus which is the preferred species in foreign markets for its thicker gel, kappa carrageenan (vs. the weaker iota carrageenan from Eucheuma). New efforts are put to curb these problems including moving seaweed farms to deeper waters and cultivation trials of other carrageenophytes as well as agar-producing species, agarophytes. Research work has been initiated to evaluate Gracilaria and Hypnea farming and processing in Tanzania, the Republic of Mauritius and Mayotte. Gracilaria farming is at experimental stages as a biofilter of fishpond effluents and as potential species for the production of agar with growth rates of 1.5–1.9 % day^?1. Hypnea farming is only being initiated in Mauritius and Mayotte at present. Other innovations including value addition by making various seaweed products and encouraging the consumption of seaweed as food at least in Tanzania and Mauritius are increasing further the importance of the seaweed farming and processing industry in the WIO Region.     

Recent trends of seaweed production in Chile

In the last fourteen years the production of seaweeds in Chile has ranged from 74 000 to 229 000 wet metric tons per year and has included about twenty species belonging to Phaeophyta and Rhodophyta. The only source of this production has been the exploitation of natural beds, except for Gracilaria, which is the only case of commercial cultivation and contributes significant quantities to total production. Initially most of the raw material was exported but currently important quantities of Gracilaria and several carrageenophytes are being processed by local industry. Changes in production of the main resources are analyzed with consideration of potential demand, level of knowledge about natural beds, and the situation of total Gracilaria farming, in order to attempt predictions for the supply. Current possibilities of applying new technologies to cultivate other economically important Chilean seaweeds are also analyzed and discussed.     

Advances in Seaweed Aquaculture Among Pacific Island Countries

Recent developments in the seaweed aquaculture industries of Pacific islands are reviewed from the perspective of technical, production, geographic, marketing, species-diversification, socio-economic and institutional-support advances. Successful commercial aquaculture of seaweeds in the Pacific island region is presently based on two species, Kappaphycus alvarezii in Kiribati, Fiji and Solomon Islands, and Cladosiphon sp. in Tonga. It is possible that other candidate species could be considered for aquaculture for food (e.g. Caulerpa racemosa or Meristotheca procumbens) or extraction of agar (Gracilaria), although further research on the technical feasibility of aquaculture methods to produce sufficient tonnage, and particularly on their marketing, is needed. While the Pacific island region may be environmentally ideal for seaweed aquaculture, the limitations of distance from main centres and distance from markets, vulnerability to world price fluctuations, and socio-economic issues, make it unlikely that the Pacific Island region will ever rival the scale of Asian seaweed production. Regional seaweed farming can nevertheless make a useful contribution to supplement other sources of income, and can be an important economic boost for isolated outer islands where few alternative income-generating opportunities exist.     

Experimental tank cultivation of Gracilaria sp. (Gracilariales,Rhodophyta) in Ecuador

This paper describes experiments to grow a local and still unidentified species of Gracilaria in shrimp hatcheries in Ecuador. The experiments used outdoor tanks of 1 and 18 m³ capacity, with continuous aeration and water renewal every two and five days, respectively. The sea water (salinity 34 ppt) was enriched with Guillard's f/2 medium; light and temperature were monitored but not controlled. One kg of fresh seaweed, inoculated into each tank, produced a biomass of ca. 3 kg in a period of 35 days in the 1 m3 tank and 18 kg in 43 days in the 18 m³ tank. We therefore believe that it is technically feasible to use the large infrastructure of existing shrimp hatcheries in Ecuador to produce Gracilaria.     

Population dynamics and culture studies of the edible red alga Callophyllis variegata (Kallymeniaceae)

Callophyllis variegata is a red alga that has been exported to Japan as an edible seaweed over the past few years. Available data strongly suggest that after a few years of exploitation of the C. variegata stands in southern Chile, a decline of its abundance seems to be occurring. However, there is not sufficient knowledge available to sustain harvesting strategies or to develop cultivation techniques. This study describes the C. variegata landings in the south of Chile and also provides some basic data on the biology of this species. Experiments related to the cultivation of early developmental stages, frond cultivation under controlled conditions and the regeneration capacity of the holdfast of this red alga are also presented. Spore production occurs mainly in autumn and winter and survival of carpospores decreased as the temperature increased from 8 to 12°C. Survival of tetraspores increased significantly, from 50 to 60% to over 80%, when temperature was raised from 8 to 12°C. Carpospore survival was also significantly affected by the photon flux density. This effect was mainly at 8°C, whereas at 33 µmol m^?2 s^?1 the survival of the spores is always low. The cultivation of apical portions of C. variegata under laboratory conditions showed that lower temperatures (8°C) significantly increased growth. Salinity and photon flux density did not have an effect on specific growth rate. Laboratory experiments demonstrated that holdfasts can regenerate fronds and that these fronds can be excised and cultivated, and are far more tolerant to environmental factors than the apical portions.     

European bioconversion projects and realizations for macroalgal biomass : Saint-Cast-Le-Guildo (France) experiment

Proliferation of macroalgae is a world-wide problem with 50,000 m³ of drift Ulva harvested per year in Brittany and about 1.0 to 1.2 million tons growing in the Venice lagoon. This biomass may be treated by bioconversion (aerobic or anaerobic fermentation) to give useful products (gas, fertilizers or others) and to remove a source of environmental pollution. Such a treatment also may be applied to cultivated or harvested seaweds and to seaweed industry residues.Studies of seaweed methanization showed Laminaria an especially good substrate and Ulva a possible substrate. Research led to a defined way of treating drift algae, encompassing natural hydrolysis and pressing with methanization of the juices.The most advanced full-scale realization for algal biomass utilization is the C.A.T.-Quatre-Vaulx composting plant in Saint-Cast-Le-Guildo (Brittany, France). It produced from seaweed, wood and animal dung a biological quality compost that is competitive with the traditional market products.     

Gracilaria phuquocensis sp. nov., a new flattened Gracilaria species (Gracilariales,Rhodophyta), previously recognized as G. mammillaris,from the southern coast of Vietnam

Flattened Gracilaria species are widely distributed along the coasts of the South China Sea with more than 20 species recorded. Within the South China Sea, Gracilaria mammillaris has only been reported from Vietnam, but this species is likely restricted to the western Atlantic. This study aimed to reevaluate the taxonomic status of Vietnamese specimens of ‘G. mammillaris’ using combined morphological and molecular data. Our data clearly indicated that Vietnamese specimens were morphologically and genetically distinct from authentic G. mammillaris from the western Atlantic, and also other described flat Gracilaria species. We, therefore, propose that specimens from Vietnam originally identified as G. mammillaris be designated as a new species, Gracilaria phuquocensis sp. nov. Morphologically, G. phuquocensis can be distinguished from other flat Gracilaria species by its small thallus size, narrower blades, many medullary layers, abundant basal nutritive filaments within mature cystocarps, and tetrasporangial nemathecium. Our rbcL sequence analyses showed that the new species was sister to Gracilaria rhodymenioides from Thailand, and these two species formed a clade with cylindrical Gracilaria species. Our study contributes to clarification of the taxonomic status of misidentified specimens attributed to the flattened Gracilaria species in the South China Sea.     

Cultivation of red seaweeds: a Latin American perspective

The Latin American seaweed industry plays an important role at a global scale as 17 % of all seaweeds and 37 % of red seaweeds for the phycocolloid industry comes from this region. Increased market demand for algal raw materials has stimulated research and development into new cultivation technologies, particularly in those countries with economically important seaweed industries such as Argentina, Brazil, Chile, México, and Peru. The marine area of Latin America includes almost 59,591 km² of coastline ranging in latitude from 30ºN to 55ºS and encompasses four different oceanic domains: Temperate Northern Pacific, Tropical Eastern Pacific, Temperate South America, and Tropical Atlantic. Commercial cultivation of red seaweed in Latin America has been basically centered in the production of Gracilaria chilensis in Chile. Attempts have been made to establish seaweed commercial cultivation in other countries, going from experimental research-oriented studies to pilot community/enterprise based cultivation trials. Some genera such as Kappaphycus and Eucheuma have been studied in Brazil and Mexico, Gracilaria species in Argentina and Brazil, Gracilariopsis in Peru and Venezuela, and Chondracanthus chamissoi in Peru and Chile. In this short review, we address the Latin America perspective on the status and future progress for the cultivation of red seaweeds and their sustainable commercial development, and discuss on the main common problems. Particular emphasis is given to the needs for comprehensive knowledge necessary for the management and cultivation of some of the most valuable red seaweed resources in Latin America.     

Cultivation of Gracilaria on the sea-bottom in southern Chile: a review

This review contains information about the cultivation techniques, strategies, problems and new challenges faced as well as an economic analysis of the income-producing capacity of Gracilaria farming, considering the variability of environmental systems where this alga is cultivated in southern Chile. The development of Gracilaria farming in Chile was made possible by an increased market demand, as well as the existence of basic knowledge that permitted the management of wild stocks and the initiation of cultivation practices. Subtidal cultivation systems appear to be more productive than intertidal systems and are less susceptible to wave action than intertidal cultivation areas. In relation to farming practices, this difference implies that planting and harvesting methods and strategies vary between habitats where cultivation is being carried out on a commercial scale. Several problems such as the environmental impact of different cultivation methods adopted by the farmers, the management of contaminating organisms and strain selection appear to be important and new areas for future research. Finally, an analysis of the income-producing capacity indicates that environmental differences also have important consequences for the management strategies of Gracilaria cultivation.     

Bioactive compounds in seaweed: functional food applications and legislation

Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value-added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews worldwide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value-added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed.     

Recent status of Gracilaria cultivation in Taiwan

The recent decrease in Gracilaria culture production and value in Taiwan were evaluated from statistical data and from interviews with local fishermen. Reasons are: 1) during 1986–87, many Gracilaria culture ponds were transformed to grow grass shrimp (Penaeus monodon) in monoculture, but disease of the shrimp occurring soon after stopped such production and Gracilaria culture took over, but 2) due to manpower shortage, Gracilaria-farmers prefer to sell their crops to abalone farmers and not to agar factories. Since Gracilaria as abalone feed is cheeper than for agar production, the value of algal crop decreased.     

The effect of localised eutrophication on competition between Ulva lactuca (Ulvaceae,Chlorophyta) and a commercial resource of Gracilaria verrucosa (Gracilariaceae,Rhodophyta)

In spring (August) 1993 a bloom of Ulva lactuca appeared for the first time in Saldanha Bay, South Africa, and persisted through summer. Ulva wash-ups contaminated the beach and part of the commercial Gracilaria beach-cast had to be discarded. The biomass and distribution of Gracilaria and Ulva are described in relation to the seasonal water chemistry of the bay. Gracilaria survives in deeper water in summer by the pulsing of nutrients on an approximately 6-day cycle of movement of the thermocline that separates nutrient-rich bottom water from warm oligotrophic surface water. Ammonium-rich fish-factory discharge into this surface layer in a sector of the bay provided localised conditions for Ulva to out-compete Gracilaria at depths of 2–5m, demonstrating the powerful disruptive effect of eutrophication in this strongly stratified system.     

Opportunities and challenges for the development of an integrated seaweed-based aquaculture activity in Chile: determining the physiological capabilities of <Emphasis Type="Italic">Macrocystis</Emphasis> and <Emphasis Type="Italic">Gracilaria</Emphasis> as biofilters

Seaweed production is a reality in Chile. More than ten species are commercially used to produce phycocolloids, fertilizers, plant growth control products, human food or animal fodder and feed additives. These multiple uses of algae offer a number of possibilities for coupling this activity to salmon, abalone and filter-feeder farming. In this context, different experiments carried out in Chile have demonstrated that Gracilaria chilensis and Macrocystis pyrifera have great potential in the development of an integrated aquaculture strategy. The present Integrated Multi-Trophic Aquaculture (IMTA) approach study showed that Gracilaria can be cultured best at 1 m depth whereas Macrocystis has an especially good growth response at 3 m depth. Both species use available nitrogen efficiently. On the other hand, high intensities of solar radiation (UV and PAR) can be critical at low depths of cultivation, and our results indicate that both species show photosynthetic susceptibility mainly at noon during the summer. The demand of Macrocystis for abalone feeding is increasing, thus improving the opportunity for developing an integrated nutrient waste recycling activity in Chile. Although Gracilaria shows a higher nitrogen uptake capacity than Macrocystis, its market value does not yet allow a massive commercial scaling.