Worldwide distribution of commercial resources of seaweeds including Gelidium

The commercial exploitation of seaweeds for use as food and for the production of agar, alginate and carrageenan is outlined. The quantities of seaweed harvested for each purpose are tabulated and discussed. Seaweeds for food are derived chiefly from China, Japan and Korea, with almost 94% obtained by cultivation. Alginophytes are collected in 15 countries but six of these account for more than 80% of the total harvest; all are from natural stocks except for a large quantity of Laminaria cultivated in China. Natural carrageenophytes, from 12 countries, now account for only 20% of the total harvest; the remainder is cultivated Eucheuma species, 99% of which is produced in only two countries, the Philippines and Indonesia. Of the four categories of commercial resources of seaweeds considered, agarophytes are spread more evenly over a greater number of countries; they come from 20 countries and only five of these are minor contributors to the total. Gelidium species are particularly important because of the high quality agar they yield; their distribution and location are discussed.     

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.     

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.     

A decade of change in the seaweed hydrocolloids industry

Seaweed hydrocolloid markets continue to grow, but instead of the 3?C5% achieved in the 1980s and 1990s, the growth rate has fallen to 1?C3% per year. This growth has been largely driven by emerging markets in China, Eastern Europe, Brazil, etc. Sales of agar, alginates and carrageenans in the US and Europe are holding up reasonably well in spite of the recession. However, price increases to offset costs in 2008 and 2009 have begun to have a dampening effect on sales, especially in markets where substitution or extension with less expensive ingredients is possible. These higher prices have been driven by higher energy, chemicals and seaweed costs. The higher seaweed costs reflect seaweed shortages, particularly for carrageenan-bearing seaweeds. The Philippines and Indonesia are the dominant producers of the farmed Kappaphycus and Eucheuma species upon which the carrageenan industry depends and both countries are experiencing factors limiting seaweed production. Similar tightening of seaweed supplies are beginning to show up in brown seaweeds used for extracting alginates, and in the red seaweeds for extracting agar. The structure of the industry is also undergoing change. Producers in China are getting stronger, and while they have not yet developed the marketing skills to compete effectively in the developed world markets, they have captured much of their home market. China does not produce the red and brown seaweeds needed for higher end food hydrocolloid production. Stocking their factories with raw material has led to the supply problems. Sales growth continues to suffer from few new product development successes in recent years; although some health care applications are showing some promise, i.e., carrageenan gel capsules and alginate micro-beads.     

Bioremediation potential of three carrageenophytes cultivated in tanks with seawater from fish farms

Intensive fish farming discharges large amount of nutrients, the majority of which are composed of dissolved nitrogen in ammonium form, which promotes eutrophication in coastal waters. Macroalgae have been proven to effectively reduce the nutrients of fish farm effluents and at the same time increase the economic output of the aquaculture system when economically important species are utilized. In this study, the potential of three high value carrageenophytes (Kappaphycus alvarezii, Kappaphycus sp., K. striatum) to extract ammonium in fish farm effluent collected from a milkfish (Chanos chanos) fish cage was investigated. To establish economic viability of the integrated culture system, the effects of elevated total ammonia of fish farm effluent on the growth rate, phycocolloid content, and quality of these seaweeds were determined. Tank cultivation trials showed that the three carrageenophytes substantially reduced the ammonium content of the fish farm effluent (41–66% reduction efficiency) and consequently attained maximum daily growth rates of 4.41%, 2.90%, and 2.75% for K. striatum, Kappaphycus sp., and K. alvarezii, respectively. Their carrageenan content was improved. Carrageenan quality, however, was not significantly enhanced. Elevated ammonium in fish farm effluent did not adversely affect the performance of tank cultivated Kappaphycus; thus, future integration of these seaweeds in fish farms is feasible. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Carrageenan yield and properties of Eucheuma uncinatum (Seth. & Gard.) Daw. cultured under natural conditions

Eucheuma uncinatum (Setch. & Gard.) Daw. from the Gulf of California was cultured in 1001 tanks in outdoor conditions. The cultures consisted of a 3 × 3 factorial design of 10, 19 and 33 % incident light and three different conditions of nutrients during winter (0; 20 µM N0₃; and 20:2 µM NO₃:PO₄) and summer (0; 40:4; and 80:8 µM of NO₃:PO₄). Best growth and carrageenan yield conditions were determined under each experiment. Carrageenan extracts were analyzed for total carbohydrates, 3,6-anhydrogalactose anhydrogalactose and sulphates. Higher carrageenan yields were obtained from cultures with fertilized plants under higher light conditions from winter and summer experiments although summer cultures provided the highest yields (48%). During summer a direct relationship between nutrients and sulfate content was observed. This effect was not observed in the winter experiment. An inverse carbohydrate: light relationship was observed in winter but not in summer. Maximum values of 3,6-anhydrogalactose in winter and summer were 23.9% and 18%, respectively. Results indicate that there is the potential to increase yield and quality of Eucheuma uncinatum carrageenan cultured under natural conditions.     

Use of Tissue Culture and Biotechnology for the Genetic Improvement of Watermelon

Watermelon is an important vegetable crop world-wide with over 81 million metric tons produced annually. Despite these high production figures, million of metric tons of fruit are lost in fields to disease. Genetic improvement through tissue culture and biotechnology offer potential routes of improving fruit harvest by offering higher quality products, like seedless fruit, or by introducing recombinant genes or generating somaclonal variants with improved resistance to biotic or abiotic stresses. The purpose of this review is to highlight how tissue culture and biotechnology have been used for the genetic improvement of watermelon and provide suggestions for future application of these methods to facilitate further genetic improvement.     

Potential fishery of Nile perch Lates niloticus Linne (Pisces: Centropomidae) in Nyanza Gulf of Lake Victoria,East Africa

From bottom trawls, Lates niloticus (Lin.) in Nyanza Gulf was observed to have a gulf-wide distribution. Lates dominated the catch at Homa point. Catch rates in kg h^-1 varied from one location to another and from month to month.Its estimated production is 11 000 metric tons, netting about 22 000 000 Kenya shillings (US $2 000 000).Abundance of food items such as freshwater shrimps of the genus Caridina, and Engraulicypris argenteus, have been used as basis for estimating the growth and production of Lates.     

Seasonal variation in growth and carrageenan content ofCalliblepharis jubata (Rhodophyceae,Gigartinales) from the Normandy coast,France

Study of the seasonal variation in the quality and content of iota carrageenan inCalliblepharis jubata from the Normandy coast of France shows that seasonal fluctuation of the environment affects the growth and chemical composition of this red alga. Growth increases during winter, when there is little synthesis of carrageenan and floridean starch is accumulated. When inorganic nitrogen content decreases, growth also decreases and stops (May to August); with high light intensity, the metabolism is oriented towards a synthesis of parietal carrageenans to the detriment of the reserve products such as floridean starch.Author for correspondence     

Prospects for the cultivation of economically important carrageenophytes in Southeast Mexico

Carrageenan, a hydrocolloid used in the food and pharmaceutical industry mainly as a thickener and stabilizer, has an annual global market of US $450 million. In Mexico, carrageenan imports doubled during the last years, reaching 4,400 t in 2008. Any carrageenan industrial project demands a regular supply of raw material from reliable sources capable to meet and maintain required volumes and qualities. Some carrageenophytes have been exploited traditionally in Baja California Peninsula (i.e., Chondracanthus canaliculatus). The recent demand, however, for carrageenan has increased the development of cultivation of economically important seaweeds mainly in the tropics. In the Yucatan peninsula, experimental cultivation of native and exotic species has been carried out during the last 10 years. Eucheuma isiforme, Solieria filiformis, Halymenia floresii, and the introduced Kappaphycus alvarezii represent potential raw material sources for the production of carrageenan. Demand for iota carrageenan-producing species which could be sourced from native species is not a market priority. On the contrary, the most in demand are kappa and lambda carrageenan-producing species. In this study, we analyze the prospects for the commercial cultivation of tropical economically important seaweeds in the Yucatan peninsula.     

Cultivation of Gigartina skottsbergii (Gigartinales, Rhodophyta): Recent advances and challenges for the future

This study integrates landings statistics and biological studies of the red algaGigartina skottsbergii Setchell & Gardner. The analysis of the landings and carrageenan production in Chile suggeststhat this resource will suffer a strong harvesting pressure during the nextyears. Biological results on sporulation, germination, sporeling growth and survivorship in laboratory,indoor tanks and field conditions, indicated that cultivation of this species istechnically feasible, as spores can be seeded on ropes and other substrata. Vegetative propagation of this species through tissue fragmentationis also possible. Vegetative fragments of this carrageenophyte have 20 to30% higher growth rates than whole fronds in suspended culture systems. Protoplast production can be also explored for bypassing restrictions inspore availability. Major advantages that encourage the cultivation of G. skottsbergii include its gel quantity and quality, its pathogen-freecondition, a high reproduction potential and its regeneration capacity. Onthe other hand, the major constraints are related to its relatively slowgrowth as compared to other carrageenophytes, limited availability ofspores and high mortality during juvenile stages.     

Aspects of the farming and processing of Kappaphycus and Eucheuma in Indonesia

Indonesia has become the largest exporter of Eucheuma denticulatum, supplying the foreign demand for iota-carrageenan, and the increasing demand of the Asian food markets. Recent demand fluctuations for Kappaphycus alvarezii and E. denticulatum have resulted in price instability, and slowed the expansion of the less viable raft culture practice. A short 42–45 day harvest interval, propagule selection, and post-harvest treatment remain the causes of poor crop quality and low carrageenan yields.In 1988 the first processing of K. alvarezii commenced. By 1991 there were four factories exporting an alkali-treated chip product, and one producing carrageenan powder. In 1991, 3200t dry weight of the K. alvarezii harvest was processed locally. The viability of future natural food-grade carrageenan production is discussed in relation to new developments in the industry.     

Effects of environmental factors on carrageenan fromGymnogongrus griffithsiae (Gigartinales,Rhodophyta)

The effects of environmental factors on substratum coverage, thallus length, production of iota carrageenan and gelling behavior were investigated in field populations of the red algaGymnogongrus griffithsiae (Turner) Martius. Irradiance and water temperature affected thallus substratum coverage and water gel strength of the carrageenan. The significant monthly differences in thallus length, carrageenan content and carrageenan gelling properties were not attributable to seasonal variations in irradiance and water temperature. The effect of temperature and N loading on biomass productivity, carrageenan yield and gelling characteristics were also investigated using cultures. N-enriched cultures showed decreased gel yields, higher viscosities and higher water gel strengths in the carrageenans extracted from these cultures. Milk reactivity tests were correlated with thallus nitrogen and water dessert gel strength, but neither culture temperature nor N loading showed a significant effect. The field and culture studies indicate how temperature, irradiance and N availability affect growth and hydrocolloid production.Author for correspondence     

Laboratory and field growth studies of commercial strains ofEucheuma denticulatum andKappaphycus alvarezii in the Philippines

Daily growth rates of 0.1 to 8.4% d^-1 for the brown form and 0.2 to 6.3% d^-1 of the green form were measured for 3 to 5-cm long branches of the tropical red seaweedKappaphycus alvarezii cultured in the laboratory. Highest growth rates were found using inexpensive enrichments such as soil water and coconut water supplemented with 0.7 mM N and 13 µM P and with a liquid fertilizer, Algafer, produced from seaweeds in the Philippines. Laboratory grown branches of bothK. alvarezii andEucheuma denticulatum transplanted to rafts in the field showed daily growth rates of 4.4 to 8.9% d^-1, as high or higher than other reported growth rates. The studies, carried out in the Philippines, demonstrate the viability and high yield of laboratory cultivars and methods to keep laboratory culture costs low.     

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.     

Interactions between environmental variables on growth rate and carrageenan content of Solieria chordalis (Solieriaceae,Rhodophyceae) in culture

Using vegetative propagules (ramuli) of the iota carrageenan producing red seaweed Solieria chordalis, a maximum growth rate of 6.8% d⁻¹ was achieved when cultured at 20 °C and 100 μmol photon m⁻² s⁻¹ in seawater supplemented with 20 μM NO₃-N or 10 μM NO₃-N plus 10 μM NH₄-N. Ramuli grew less well when nitrogen was supplied solely as NH ₄ ⁺ . Maximum carrageenan content was observed at the same temperature, irradiance and salinity as growth, but at lower nitrogen concentrations. These findings are discussed in relation to results obtained from studies on other iota-carrageenan producing carrageenophytes.     

A comparative analysis of phycocolloids produced by underutilized versus industrially utilized carrageenophytes (Gigartinales, Rhodophyta)

Carrageenan (E-407) and semi-refined carrageenan (E-407a) are some of the main additives used by the food industry for their gelling, emulsifying, thickening, and stabilizing properties. These are natural ingredients, which have been used for decades in food applications and are generally regarded as safe. Internationally, sub-tropical carrageenophytes (e.g., Kappaphycus alvarezii) are cultivated extensively as a source of raw materials for industrial extraction, and their use as potential candidates in integrated multitrophic aquaculture is tentative. We analyzed carrageenan yield (as a percentage of dry weight) and chemical composition (by Fourier transform infrared attenuated total reflection and Fourier transform-Raman) of extracts produced by several carrageenophytes (Gigartinales, Rhodophyta), from different origins, e.g., K. alvarezii (Tanzania, Indonesia, the Philippines, Panama, and Mexico), Kappaphycus striatum (Madagascar), Eucheuma denticulatum (Tanzania, the Philippines, and Madagascar), Betaphycus gelatinum (the Philippines), Chondracanthus chamissoi, and Sarcothalia crispata (Chile). For comparison, some underutilized carrageenophytes were also analyzed, e.g., Chondrus crispus, Mastocarpus stellatus, Gigartina pistillata, Chondracanthus teedei var. lusitanicus, Chondracanthus acicularis, Calliblepharis jubata, Gymnogongrus crenulatus, and Ahnfeltiopsis devoniensis (Portuguese carrageenophytes). The main findings were that the highest carrageenan yield was obtained from K. striatum (Madagascar) with 75.6 (percent dry weight (% DW)); B. gelatinum and K. alvarezii (both from the Philippines) had yields of 71.0% and 68.0% (% DW), respectively; and G. pistillata (Portugal) 65.4% (% DW). Spectroscopic analysis of the phycocolloids allowed determination of a wide range of carrageenan types, e.g., pure iota carrageenan, several kappa–iota hybrid carrageenans with different iota/kappa ratios, and kappa–beta, xi–theta, and xi–lambda hybrid carrageenans.     

The impact of seaweed life phase and postharvest storage duration on the chemical and rheological properties of hybrid carrageenans isolated from Portuguese Mastocarpus stellatus

Variations in chemical and gelling characteristics of hybrid carrageenan extracted from Mastocarpus stellatus seaweeds are studied in order to explore potential links between the seaweeds life phase, the seaweeds postharvest storage duration and the phycocolloids properties. Chemical structures of phycocolloids were assessed by Fourier Transform Infrared spectroscopy (FTIR) and ¹H NMR spectroscopy. Rheological properties of hybrid carrageenans, such as intrinsic viscosity ([η]), gel elasticity (G₀), gel setting temperature (T_g) and gel melting temperature (T_m), were measured with a stress rheometer. Seasonal variation in the degree of sulphates of native extracts and in their corresponding gelling properties is found. The minimum in gelling properties coincides with a minimum of fructified gametophytes in populations harvested during the cold season. Alkali treated extracts also show minimum gelling properties during the cold season but no correlation with variations in the chemical characteristics could be identified. The gel setting temperature is the only significant change in the properties of hybrid carrageenans extracted from dried seaweeds stored over 39 months in opaque and sealed plastic bags. These results point to non trivial relationships between the life stages of M. stellatus seaweeds, the chemical structure and gel properties of the alkali-extracted phycocolloids, and suggest a route towards the sustainable exploitation of the natural resource.     

Ethnobotany of seaweeds: clues to uses of seaweeds

Extensive uses of fresh and dried seaweeds by coastal populations over the world can furnish clues to potential food and other uses of seaweeds, just as the first extraction of a seaweed gelatin now used for bacteriological purposes was discovered by a housewife in search of a pudding. Ethnic uses as food depend heavily on closely related species suitable for making cool, gelatinous dishes or concoctions, or on species suitable for adding to soups or stews. Rarely, single species like cochajugo (Durvillea antarctica) in Chile and rimu (Durvillea antarctica) in New Zealand point to different kinds of food preparation. Oriental cuisine incorporates many different species of seaweeds in a wide variety of ways, whereas commercial western uses depend upon extracts of wall materials to suspend, emulsify or stabilize a broad variety of foods and products.     

MONOCLONAL ANTIBODIES AS MOLECULAR MARKERS FOR THE INTRACELLULAR AND CELL WALL DISTRIBUTION OF CARRAGEENAN EPITOPES IN KAPPAPHYCUS (RHODOPHYTA) DURING TISSUE DEVELOPMENT1

Carrageenan, the major cell wall carbohydrate of certain red algae, is variable in structure and gelling properties. Sequence types include gelling (kappa and iota) and nongelling (lambda) types in addition to precursors, often in hybrid molecules containing more than one precursor and/or sequence type. Molecular markers to subunits were needed to study carrageenan synthesis, cell wall organization, and the relationship between structure and function. Monoclonal antibodies were produced to carrageenan, and their specificities were determined by competitive enzyme immunoassay. Antibodies were identified with specificities related to kappa, iota, and lambda carrageenan. The patterns of immunofluorescence localization on Kappaphycus alvarezii = Eucheuma alvarezii var. tambalang (Doty) sections were distinctive for each antibody. The antibody to a kappa-related epitope labeled mature tissue strongly; antibodies to an iota-related epitope and a lambda-related epitope labeled weakly, consistent with the kappa-enriched carrageenan produced by this alga. Kappa-related epitopes were distributed throughout the wall and matrix, whereas iota-related epitopes were concentrated in the middle lamella. Lambda-related epitopes were localized primarily at the plant cuticle where kappa and iota antigens were lacking. An antibody appeared to be specific for a precursor of the gelling subunits because it showed maximal wall and intracellular labeling at the youngest developmental stage. All antibodies labeled intracellular inclusions in the transition zone between the epidermis and medulla during the development of medullary cells from the peripheral meristem in young branches. The results demonstrate the intracellular synthesis of epitopes related to all major carrageenan subunits and their differential extracellular distribution.