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.     

World seaweed utilisation: An end-of-century summary

The data for worldwide seaweed production for the years 1994/1995 are summarised. At least 221 species of seaweed were used, with145 species for food and 101 species for phycocolloid production. 2,005,459 t dry weight was produced, with 90% coming from China, France, UK, Korea, Japan and Chile. 1,033,650 t dry weight was cultured with 90% coming from China, Korea and Japan. Just four genera made up 93% of the cultured seaweed: Laminaria (682,581 t dry wt), Porphyra (130,614 t dry wt), Undaria (101,708 t dry wt) and Gracilaria (50,165 t dry wt). The value of the harvest was in excess of US $ 6.2 billion. Since 1984 the production of seaweeds worldwide has grown by 119%. This revised version was published online in June 2006 with corrections to the Cover Date.     

The agar component of the red seaweed Gelidium purpurascens

Chemical composition and rheological properties of agar isolated from Gelidium purpurascens, the agar after alkaline treatment, and a commercial agar are presented. The agar and alkali-treated agar gave weaker gels, as measured with an Instron 1122, than those of commercial agar. Xylose, glucose and glucuronic acid in the agar were removed together with 86% of the nitrogen content on alkaline treatment, indicating occurrence of these residues as carbohydrate-protein complexes. Sequential extraction of the alga accounted for low yields of agar as losses incurred on ethanol precipitation. Acid treatment of the residue from exhaustive aqueous extraction of the alga liberated a further 10% agar with increased gel strengths despite increased glucose inclusion, suggesting a lack of involvement of these ‘contaminant’ carbohydrate-protein residues in helix coil formation during gelling.     

Seaweeds of potential economic importance in Kenya: field survey and future prospects

Kenya is a net importer of agar and alginate based on recent government statistics, although it may have the potential to be self-sufficient or even an exporter of these phycocolloids. There is little information on carrageenan importation into Kenya since government statistics incorporate it as agar. Seaweeds are relatively unimportant in the Kenyan diet since they are consumed rarely by coastal people. A survey of 15 sites along of the Kenyan coast evaluated the potential for harvesting seaweeds and for establishing seaweed farms. Gracilaria appears to comprise the bulk of the low grade agar import, even though local species of this genus are widely distributed along the Kenyan coast. Major populations of Gelidium may be a potential source of high quality bacteriological grade agar. Eucheuma may be farmed locally to support the increasing local and regional demands for carrageenan. Recommendations for a national program of management and production for Kenya will be discussed.     

海藻场生态系统及其工程学研究进展

海藻场生态系统是典型近岸生态系统之一,其独特的结构和功能使其生态系统生态学研究及其工程学研究在近年来日益引起国际学术界关注.本文着重介绍了海藻场生态系统的概念、基本结构、生态功能及其生态工程的概念与基本实施步骤等,并以美国、日本为例,介绍了发达国家的海藻场生态工程的研究与实践现状.结合我国现已开展的海藻场生态系统生态学的相关研究,呼吁我国尽快组织开展相关的基础研究,以期尽快发挥海藻场生态工程对我国海洋经济与科技发展的积极作用.     

Effect of seaweed concentrate on the growth and mineral nutrition of nutrient-stressed lettuce

The effects of the seaweed concentrate Kelpak on the growth and mineral nutrition of lettuce plants grown under conditions of varying nutrient supply were investigated. Kelpak significantly increased the yield and the concentration and amounts of Ca, K and Mg in the leaves of lettuce receiving an adequate supply of nutrients, but had little effect on nutrient stressed plants. Results are discussed in relation to the physiological mechanisms that have been proposed to explain the beneficial effects of seaweed concentrate on plants.author for correspondence     

Effect of seaweed concentrate on hydroponically grown spring barley

Spring barley (Hordeum vulgare cv. Triumph) was grown hydroponically over a 6-week period. Two treatments were incorporated either into the hydroponic solution or sprayed onto the plants at rates of 1 ml per 3 litres. The treatments applied were: (i) a seaweed concentrate prepared fromAscophyllum nodosum (L.) Le Jolis (marketed as Maxicrop Triple), (ii) a ‘Trace element’ treatment incorporating the micro and macro nutrients added to the seaweed extract base to produce the formulated product Maxicrop Triple and (iii) a control treatment. Irrespective of the mode of application, plants treated with Maxicrop Triple grew faster than plants under either of the two other treatments. Elevated growth rates were also found for the ‘Trace element’ treated plants when incorporated into the hydroponic solution. At the final harvest, plants with Maxicrop Triple incorporated into the hydroponic solution showed increases from 56–63% over the control treatment for the growth characteristics measured. ‘Trace element’-treated plants produced increases of between 25–45%. When the treatments were sprayed the effect was less pronounced. Maxicrop Triple increased growth characters by 35–38% and the ‘trace element’ treatment gave increases in the range of 2–13%.     

A study of the phycocolloids from Gelidium madagascariense and Eucheuma denticulatum (Rhodophyta) collected on the south coasts of Madagascar

Several species of red algae known to contain agar or carrageenan are abundant on the southeast and southwest coasts of Madagascar. The agarophyte Gelidium madagascariense, collected in the Fort Dauphin area, has been exported on a small scale to Japan for several years. FT-IR and GLC analysis show that it contains an agar polymer, of which the methylated fraction contains predominantly 6-O-methyl galactose and traces of 4-O-methyl galactose. Eucheuma denticulatum grows profusely on the coral reefs in the Tulear area. FT-IR and GLC analysis show that it contains iota-carrageenan, with no methyl-derivative contaminants. The 3,6-anhydro-galactose content was found to be rather low, suggesting a possible contamination with deviant iota. The economic potential of other sources of phycocolloids, as well as the possibility of farming different species of Eucheuma in the Tulear area, is discussed.     

Polysaccharide and lipid composition of the brown seaweed <Emphasis Type="Italic">Laminaria gurjanovae</Emphasis>

Polysaccharide and lipid composition of the Pacific brown seaweed Laminaria gurjanovae is determined. Alginic acid is shown to be the main polysaccharide of its biomass (about 28%); it consists of mannuronic and guluronic acid residues at a ratio of 3: 1. The yield of water-soluble polymannuronic acid is low and does not exceed 1.1% of dry biomass. High laminaran content (about 22%) is found, whereas the yield of fucoidan is no more than 3.6%. Laminaran consists of two fractions, soluble and insoluble in cold water, their ratio is 2.5: 1. Insoluble laminaran is a practically linear 1,3-β-D-glucan, and the soluble fraction was shown to be 1,3;1,6-β-D-glucan. The oligosaccharide products of desulfation or partial acidic hydrolysis of fucoidan were studied by MALDI TOF MS; they were found to be fuco- and galactooligosaccharides. The fucoidan is suggested to be a highly sulfated partially acetylated galactofucan (Fuc/Gal is ～1: 1). The main lipid components of the dried L. gurjanovae are neutral lipids and glyceroglycolipids, whereas phospholipids are found in minor amounts. The main fatty acid components of lipids are 14:0, 16:0, 16:1 ω-7, 18:1 ω-7 and 18:2 ω-6 acids.     

褐藻生物乙醇的研究进展

利用大型褐藻转化生产的第三代燃料乙醇已受到研究者的广泛关注。我国拥有丰富的褐藻资源,具备了褐藻生物乙醇转化的有利条件。为了实现工业化生产,还需要通过筛选分离和基因工程手段获得高效发酵褐藻的优良菌株及优化预处理、发酵条件等。主要介绍了我国褐藻资源概况、预处理方法和微生物发酵褐藻不同组分生产乙醇的研究进展,提出了当前褐藻乙醇转化中存在的问题,展望了褐藻乙醇的发展方向。     

The effect of seaweed concentrate on the growth and yield of potassium stressed wheat

The effects of the seaweed concentrate “Kelpak’ on the growth and yield of wheat grown under conditions of varying K supply were investigated. Kelpak had no significant effect on the yield of wheat receiving an adequate K supply, but significantly increased the yield of K stressed plants. The increase in yield was caused by an increase in both grain number and individual grain weight. Although the beneficial effects of seaweed concentrates have often been attributed to their cytokinin content, several lines of evidence suggested that this group of plant growth regulators may not be solely responsible for the observed effects of Kelpak on wheat. Irrespective of the physiological mechanism of action, Kelpak would appear to have considerable potential for increasing yield in K stressed wheat and may therefore reduce the requirement of wheat for K fertilization.     

Using the biogeographical distribution and diversity of seaweed species to test the efficacy of marine protected areas in the warm-temperate Agulhas Marine Province, South Africa

Aim To study the siting of marine protected areas (MPAs) with respect to the biogeographical distribution of seaweeds within the Agulhas Marine Province and to assess the effectiveness of current MPAs in including (conserving) seaweeds of the South African south coast. Location South Africa – the south coast between Cape Agulhas and the Eastern Cape/Kwazulu‐Natal border, and eight MPAs within that area. Methods We used interpolated seaweed distribution records from all available sources, in 50‐km coastal sections. Cluster analysis (Jaccard Average Linkage) of species presence/absence data provided measures of similarity between coastal sections and between MPAs. Complementarity analyses identified the sequence of ‘importance’ of sections/MPAs for conserving seaweed species. Results Species presence/absence data indicated two main groups, representing western (cooler water) and eastern (warmer water) biogeographical divisions, as well as several biogeographical subdivisions within each of these groups. Complementarity analysis yielded a sequence of ‘importance’ of coastal sections (in terms of the highest number of species included) that began with a section just east of central in the Agulhas Marine Province, around Port Alfred, where there is no MPA. This was followed by the easternmost section (warmest water), which contains the Pondoland MPA, and then by the westernmost (coolest water) section, containing the De Hoop MPA. Similar analysis of the actual species collected in MPAs showed a generally similar pattern. Main conclusions Seven current MPAs and one proposed coastal MPA in the Agulhas Marine Province appear to be well distributed and well sited to include (conserve) the full biogeographical range of seaweeds. However, if further MPAs are to be considered, the Port Alfred area is recommended for improved conservation. This study did not examine estuaries, which may require improved conservation efforts. Seaweed distribution data, which are often relatively complete, offer a good tool for planning the siting of coastal MPAs.     

Gelidium commercial exploitation: natural resources and cultivation

The state of the Gelidium agarophyte resource was last reviewed in 1990 during the First International Workshop on Gelidium. The main objective of the present study was to gather and analyse the new information made available since then, with emphasis on the G. sesquipedale resource from the Iberian Peninsula and Morocco. Other Gelidium-based resources world-wide are also reviewed, as well as new attempts to cultivate Gelidium species in the sea. In general, since the late 1980s, G. sesquipedale yields have decreased in Portugal, and increased in Spain and Morocco. Current reported values, in dry weights, are ca. 670 t yr-1 for Portugal (average 1995–1997), 5200 t yr-1 in Spain, and 6950 t yr-1 for Morocco (average 1994–1996). Efforts to develop cultivation of G. sesquipedale in the sea in Spain have yet to progress beyond the demonstration scale. Other important Gelidium-based agarophyte resources are located in: (i) South Africa where, in addition to G. pristoides, new species are being harvested, with total agarophyte landings of 140 t yr-1 in 1996; (ii) Mexico, where G. robustum harvest averaged 750 t yr-1 in 1987–1996; (iii) and Chile where harvest of Gelidium species yielded ca. 460 t yr-1 in 1990–1992. Preliminary research on new techniques for commercial cultivation of Gelidium species is also reported from these countries. This revised version was published online in June 2006 with corrections to the Cover Date.     

Impacts of feeding several components of the seaweed Ascophyllum nodosum on transported lambs

Feeding the seaweed Ascophylum nodosum (ANOD) has been previously shown to mediate the body temperature of lambs during transport in hot weather while also negatively impacting antibody production. The aim of this study was to determine if fucoidan, salt (NaCl plus potassium gluconate) or betaine, were the causative agents for the effects seen in previous studies. Each compound was fed at a rate to approximate the intake when consuming 30 g of ANOD per day. Two additional groups were fed either 30 g of ANOD per day or capsules filled with grain (i.e., controls). Fifty-five lambs (19 ewes and 34 wethers) averaging 25 ± 7 kg were used. Each lamb swallowed three gelatin capsules twice daily filled with the appropriate amount of treatment compound for 14 days. Prior to supplementation, all lambs had similar plasma cortisol and aldosterone concentrations. ANOD-supplemented lambs had suppressed (P<0.05) IgG and IgM antibody titers in response to administration of ovalbumin, and tended (P=0.10) to have higher white blood cell counts and more eosinophils (P=0.10) and lymphocytes (P=0.06) than the controls post-supplementation. Salt-fed lambs showed an increase in lymphocyte (P=0.06) counts while betaine-fed lambs had higher (P<0.05) packed cell volume and hemoglobin relative to the controls. Post-supplementation ANOD-fed and salt-fed lambs tended to have lower cortisol concentrations (P=0.08 and 0.12) than controls and all treatments had a trend (P=0.10, 0.07, 0.14, and 0.09) to lower aldosterone concentrations relative to controls. All lambs had similar mean, minimum, maximum, and range of body temperature during transport, although ANOD-fed lambs had less fluctuation in their body temperature than controls. During transport the salt-fed lambs had lower (P<0.05) cortisol concentrations than controls. Control lambs tended to have higher plasma sodium and chloride concentrations (P<0.10) post-transport than ANOD-fed lambs. All lambs lost a similar amount of body weight due to transport. Post-transport, no differences occurred in the latency of lambs to drink, eat or lie down. None of the components studied appeared to be impacting the mediation of body temperature that ANOD exhibits. The salts in ANOD appears to affect both adrenal and immune function, although further studies are needed to determine the mechanism by which it caused such large physiological impacts.     

Developments on gelling algal galactans, their structure and physico-chemistry

The wide uses of the algal galactans agar, agarose and carrageenans arebased on their unique properties to form strong gels in aqueous solutions. These gels result from peculiar regular chemical structures, specific orderedmolecular conformations and aggregations. In recent years, newmethodologies and instruments have provided a more accurate view of therelationships between the chemical structure and the gelling characteristicsof these complex hybrid and heterogeneous polysaccharides. Methanolysisand reductive acid hydrolysis procedures coupled to differentchromatographic separations allowing the quantitative determination of allthe constituent sugars including the acid labile 3,6-anhydyrogalactose areparticularly emphasised. Means of determining sugar linkages, substitutionsand sequences using chemical, enzymatic and spectroscopic methods arealso presented. Developments in multi- and low-angle laser-light diffusiondetectors coupled to high performance size exclusion chromatography nowrender the determination of molecular weight and molecular weightdistribution of these galactans more accessible. Such techniques also yieldnew information on the aggregate formation of these sulphatedpolysaccharides. These and other data question the existence of thegenerally assumed intertwined double helical conformations of thesegalactans during gel formation.