Kappaphycus alvarezii (PROSEA)
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Introduction |
Kappaphycus alvarezii (Doty) Doty ex P.C. Silva
- Protologue: P.C. Silva, Basson & Moe, Univ. Calif. Publ. Bot. 79: 33 (1996).
- Family: Solieriaceae
- Chromosome number: 2n= 20
Synonyms
- Eucheuma alvarezii Doty (1985).
Vernacular names
- Indonesia: "cottonii" (Java, Bali, Sulawesi, the common name for all Kappaphycus spp.), agar-agar, agar besar (both common names for Kappaphycus and Eucheuma spp.)
- Philippines: tamsao (northern Luzon, both for Kappaphycus and Eucheuma spp.), guso (Visayan, also for species of both genera), tambalang, kanot kanot (Ilocos Norte, for species of both genera).
Origin and geographic distribution
K. alvarezii originates from the area of the Sulu Sea, Sulu Archipelago (the Philippines) and adjacent areas (easternmost Sabah, Malaysia). It has been distributed widely by humans in recent years, for example to Indonesia, Vietnam, southern China, Hawaii, Fiji, Zanzibar and southern Africa and since 1980 has largely replaced the earlier used K. striatus (F. Schmitz) Doty ex P.C. Silva ("elkhorn variety").
Uses
K. alvarezii is a source of kappa carrageenan which is used as an additive in food, pharmaceutical and cosmetic products. In Indonesia it is sold in some supermarkets as sweets ("manisan agar") and it is used to prepare cakes ("kue").
Production and international trade
Farmed K. alvarezii is commonly used in South-East Asia as raw material for domestic industries and for export. It is presently cultured in Indonesia, Malaysia, the Philippines, Vietnam and several other tropical countries. It forms the bulk (80%) of seaweed exports from the Philippines and is commercially farmed in Sulu, Tawi-Tawi, northern Bohol, Palawan and other areas in that country. The Philippines produce about 50% of all carrageenophytes in the world, and Indonesia another 25%. In Indonesia, the main production areas are in Sulawesi and Bali. In Vietnam, where K. alvarezii does not naturally occur, cultivation has been carried out since 1993 in offshore areas, lagoons, inlets and ponds in the central and southern parts of the country. The productivity in lagoons and inlets there reaches over 10 t (dry weight)/ha/year. It is also cultivated in Malaysia (Sempora, eastern coast of Malaysia), where the total production now is about 1800 t/year (dry weight).
Production and trade data may apply to Kappaphycus spp. as a whole (although in most cases K. alvarezii is presently by far the most important), to all Eucheumoid algae (as "Eucheuma"), to the carrageenan-producing seaweeds as a whole or even to all red seaweeds together. For the Philippines in 1986 production (wet weight) by phycoculture of "Eucheuma alvarezii" was 4627 t and in 1994 12 110 t. However, phycoculture production of Eucheuma "cottonii", which probably includes K. alvarezii as well was 145 632 t (1986) and 347 300 t (1994). For 1990 the total production of K. alvarezii (now in dry weight) by phycoculture is recorded as 46 390 for the Philippines and 11 812 t for Indonesia.
Another set of production data for K. alvarezii (dry weight) shows that in 1987 the Philippines produced 40 000 t and Indonesia 5000 t.
For 1991 these data are given as 60 000 t and 15 000 t, respectively. In 1992 the total production of dried K. alvarezii in Indonesia was estimated to be 15 200 t.
In the Philippines about 10 000 ha of reef area are now used for Eucheuma denticulatum (Burm.f.) Collins & Herv. and K. alvarezii cultures, with more than 75% devoted to K. alvarezii. More than 80 000 farmers are involved and about 300 000 dependents rely on seaweed farming. Amongst these are about 10 000 personnel employed by 14 companies engaged in processing, manufacture and export of Kappaphycus and Eucheuma and their carrageenans. In Indonesia, where production is only half that of the Philippines, 7 companies are engaged in processing and manufacture, and the number of farmers, dependents and employees can be expected to be half that of the Philippines. The estimated potentially exploitable area for "Eucheuma culture" (probably including Kappaphycus culture as well) in Indonesia is 9000-10 000 ha, with a production capacity of 45 000 t per year (dry weight). This area, however, has not yet been exploited optimally: total seaweed production in 1994 was less than 27 000 t, including harvests of Gracilaria and Gelidium spp. and others. A total of 21 180 t was produced by Kappaphycus and Eucheuma.
The FOB (Free On Board) selling prices of K. alvarezii in Indonesia were rather unstable in the period 1982-1992, being US$ 0.36/kg in 1987 with a maximum of US$ 0.74/kg in 1990, and falling back to US$ 0.30-0.40/kg in 1991. This period saw increased production in Sulawesi (Indonesia), resulting in exporters carrying large stocks and thus dropping prices. In 1993 the farm gate price for properly dried K. alvarezii in the Philippines was about US$ 0.27/kg. In Malaysia it was US$ 0.42-0.50/kg in 1995 and US$ 0.44 in 1998.
In 1987 CF (Costs and Freight) prices for K. alvarezii (dry weight) in Europe were US$ 380 /t and in the United States US$ 440 t. The Kappaphycus crop is partly used directly for carrageenan production, partly exported mainly to the United States, Denmark, France, Australia, Japan, Hongkong, Singapore and China. Much of the semi-refined carrageenan is exported to companies in New Zealand, United Kingdom, Germany, France, Australia and Japan.
Properties
K. alvarezii produces a nearly ideal kappa carrageenan, which is a commercially important hydrophyllic colloid with many industrial applications. The extract is a yellowish or tan to white, coarse to fine powder that is practically odourless and has a mucilaginous consistency. Often over 60% of the wall substance of this alga is kappa carrageenan. Carrageenan properties within K. alvarezii differ considerably in gel strength, gelling temperature, melting temperature, viscosity and sulphate content. However, both cystocarpic and tetrasporophytic plants consistently produce the same kappa carrageenan and all Kappaphycus spp. contain similar kappa carrageenans.
Aqueous extracts of K. alvarezii show high cytokinin-like activity as well as gibberellin-like activity. The mineral content (dry weight) in % is N 1.2, P 0.03, K 9.3, Ca 0.23, Mg 0.62, Na 4.0 and in ppm Cu 2.5, Fe 52, Mn 4 and Zn 16.5.
Description
- Thalli rigid, bush-like, axes smooth, cylindrical.
- Branching irregular, usually not pinnate; branches reaching surface of thalli rarely inflated above their midpoints, terete in upper parts; secondary branches usually absent.
- Main axis of a thallus arising from a discoid holdfast; new main axes arising from the same base very near to the primary axis or from the main axis itself below the basal primary branch.
- Primary cells of medulla mostly isodiametric in transection; central core of axial filaments present, especially in young tissues.
- Reproductive structures on or in the lateral surfaces of otherwise normal axial segments.
- Seriately divided tetrasporangia embedded in cortex.
- Gametophytes dioecious.
- Cystocarps swollen from the cortex; spermatangia in indefinite superficial sori.
Growth and development
All stages of the triphasic life cycle have been found, which does not mean however that they all occur regularly. In culture tetrasporic plants are often lacking, while in other strains cystocarpic plants are either not found at all or only very rarely occur. The largest plant of K. alvarezii ever measured was more than 2 m long and weighed about 56 kg. Growth rates in the Philippines in cultures of K. alvarezii (% increase in fresh weight per day) vary between 1.5-5.5 and, as a yearly average 2.3% is given. A daily growth rate of about 3.5% is considered optimal, doubling the biomass in one lunar cycle of 28 days. Laboratory-grown branches transplanted to rafts in the field showed daily growth rates which are as high or even higher. In laboratory culture 3-5 cm long branches can be grown in inexpensive laboratory media prepared from autoclaved seawater enriched with either a commercial Philippine liquid fertilizer made from seaweed extract ("Algafer"), coconut water or soil extract.
In Vietnam, growth rates of 6-9%/d occur in some lagoons and inlet areas, mainly during the cool season (October-May) and even higher (10-12%/d) in areas with high nutrient concentrations. Growth rates are slightly lower, 4-6%/d, during the hot dry season (June-September) with water temperatures of 26.7-34 °C. Daily growth rates are lower in raft cultures, probably mainly due to grazing by fish.
Other botanical information
Several varieties of K. alvarezii have been isolated and grown in culture. The principal culture varieties are var. alvarezii, var. ayakii-assii (Doty) L.M. Liao and var. tambalangii (Doty) L.M. Liao. However, the formal taxonomic recognition of these "horticultural" strains is questioned, and for the two differing varieties the designations "Ajak-assi" and "Tambalang" are usually used.
Apart from these varieties colour forms or morphotypes occur in the cultivated stocks of K. alvarezii, e.g. brown, green and red morphotypes. However, these colour forms do not show any distinct sun or shade properties, although their growth rates and carrageenan properties differ considerably and consistently.
Ecology
The natural habitat for K. alvarezii appears to be the reef flat area in easternmost Sabah (Malaysia) and the northern Sulu Archipelago (the Philippines). It grows on limestone rock materials in the less sandy reef flat areas. However, it grows distinctively and rapidly in a wide range of environments. Preferred sites for cultivation are reefs far from freshwater sources since this alga is stenohaline and salinities below 30‰ may adversely affect its growth. Optimal sites are reef areas with coarse, sandy to coral bottoms and characterized by moderate water movement. Winter temperatures below 18 °C are unsuitable for year round cultivation of K. alvarezii. It can survive at low temperatures, but shows loss of photosynthetic efficiency. The alga may show negative phototropism in intense light and become prostrate and dorsiventrally flattened. This also occurs when thalli are often exposed to air, which may result in the formation of irregular "heads".
Propagation and planting
In culture, K. alvarezii is propagated by vegetative cuttings. The success of farming depends primarily on the ecological characteristics of the site, and thus on the selection of the site. After a suitable site has been identified, test planting of the desired strains is recommended, followed by careful monitoring of the test plants. In general, areas where test plants double their size within 15 days can be considered suitable for cropping. Three cultivation methods are in use: the fixed off-bottom monoline method, the raft method and the hanging long-line method.
Phycoculture
The most common technology for the cultivation of K. alvarezii in the Philippines and Indonesia is the fixed off-bottom monoline method which is cheap and easy to maintain. Wooden stakes are driven into the substrate, spaced at 1 m intervals in rows with 10 m between the rows. One end of the nylon monofilament line (180 lbs test, about 10.5 m long) is tied to a stake and tightly stretched. The other end is tied to the opposite stake in the opposite row. In Indonesia, 4 mm diameter polypropylene rope is often used for farming. Selected cuttings (50-100 g) are tied to the monoline at 25-30 cm interval using soft plastic tying materials. In culture, K. alvarezii is almost always observed to be sterile and without a primary basal discoid attachment. The plants are allowed to grow to 1 kg or more before they are harvested.
The raft method, in which the monolines are attached to a raft system usually made of bamboo frames, is used in deeper water and offshore locations. In some areas, plastic containers or bags filled with air or styrofoam floats are used. The raft is anchored to the bottom by means of nylon lines and is kept at a depth of 0.2-0.4 m below the surface. The application of the raft method is limited, due to the costs involved.
With the hanging long-line method the alga is brought nearer to the water surface at constant depths and kept buoyant with styrofoam float. This method can also be used in somewhat deeper water. It requires, however, higher investments than the fixed-bottom method. The operational costs are also higher in the Philippines due to the conditions, and the average production is lower. A decreased growth rate of K. alvarezii grown near the surface of constant-depth, was observed after the first four weeks of fast growth. The fixed off-bottom technique provides a more balanced light intensity regime and is thus more efficient for biomass production. The hanging long-line technique, however, is more effective for "seedling" source purposes, suggesting that it is more productive to culture the seaweed for the first 30-45 days by the hanging long-line and then shift to the fixed off-bottom until the seaweed can be harvested. The average annual production in the Philippines (dry weight) is 5-6 t/ha, but may be as high as 27.9 t/ha.
In Semporna (Sabah, Malaysia) in 1997 each farm was operated by a fishing family, each having on average 20-80 lines 47 m long. Stakes were used at intervals to anchor the lines, while plastic bottles acted as floats. The lines were adjusted to 0.15 m below water level, while average salinity was 34‰ and pH 8.3. Cuttings of healthy Kappaphycus weighing about 0.5 kg were tied in bunches at 0.3 m intervals along the lines. The bunches were allowed to grow until fresh weights of about 7 kg had been achieved in about 45 days. In these cultures, epiphytes were removed manually from the bundles every three days.
In Vietnam, experimental intensive cultivation of K. alvarezii in fishponds is being carried out, often in rotation with shrimp cultivation (April-September for shrimp, October-March for algae). Growth rates of 5-6%/d can be obtained especially in the cool season (air temperatures 25-28 °C, irradiance up to 50 000 lux).
Diseases and pests
One of the major problems in K. alvarezii culture is the occurrence of "ice-ice" disease, which can wipe out entire crops. The early signs are slow growth, thalli become pale losing their gloss, followed by roughening of the surface of the branches. White spots appear on the branches, and tissues soften and dissolve resulting in breakage. Entire thalli may become affected. The occurrence of "ice-ice" might be due to adverse ecological conditions as well, although whitening can also be caused by bacterial pathogens. Low light intensities, low nutrient availability, extreme water temperatures and low water movement are conducive to the development of "ice-ice". A high incidence of epiphytes may promote "ice-ice" as well, so removing heavy fouling growth of epiphytes such as those of the green alga Enteromorpha Link will diminish an outbreak of the disease.
Another constraint is "pitting". This refers to the formation of a cavity penetrating the cortex in one place and expanding into the medulla regions beneath, often resulting in thallus breakage and is probably caused by mechanical wounding of the cortex. "Tip darkening" possibly related to too cold water, and "tip discolouration" as a result of too warm water may affect K. alvarezii as well. In most cases, the affected parts of the alga decay, leading to fragmentation and losses.
Grazing by fish, especially rabbitfish (Siganids), by invertebrates and by green turtles are also major causes of loss in biomass. The use of the floating methods (raft and long lines) has virtually eliminated the effect of benthic grazers such as sea urchins, holothurians and starfish.
Harvesting
The harvest methods used for K. alvarezii are: pruning branches or collecting whole plants. Plants are harvested 30-60 days after planting. In Vietnam harvesting is done every 2-3 months in the dry season and every 1.5-2 months in the cool season. In Sabah (Malaysia) the average cultivation period is 45 days and there cultivation is carried out for 8 months a year.
Yield
The carrageenan content of K. alvarezii is about 25-70% of the salt-free dry weight. The wet (85% water) to dry (35% water) ratio is about 15%. Carrageenan content and quality of cultured material and commercial seaweed is greatly influenced by the post-harvest treatment.
Handling after harvest
Fresh material of K. alvarezii is usually sun-dried for several days to about 35% moisture and then stored and packed for export. Drying, sorting, packing and storing should be done carefully to obtain a high quality. Mats must be used to prevent contamination. Contact with freshwater, particularly rain, should be avoided, as this extends the drying time and reduces the salt content, both of which may cause the seaweed or carrageenan to degrade. Washing in freshwater does not add value and in most cases reduces the carrageenan quality.
In Sabah (Malaysia) the moisture content of sun-dried seaweed is 32-35%, but it is common practice for farmers to sell seaweed with a higher moisture content.
For both K. alvarezii and Eucheuma denticulatum inadequate drying and post-harvest contamination with sand result in poor quality and lower prices. Above 35% moisture the algal material is unstable and undergoes degradation during storage. Above 40% moisture, the carrageenan in the seaweeds may be degraded during transportation to the factory and storage. Therefore, the alga should never be stored wet. At 25-35% moisture content, the composition of the alga is relatively stable for periods longer than 12 months, and the thalli are ideally flexible for efficient baling. At lower moisture content the thalli become too brittle and can cause processing problems during carrageenan extraction. Dried material of K. alvarezii and Eucheuma denticulatum must never be mixed, otherwise it is not possible to obtain suitable carrageenan quality. The stored seaweed must be baled before transport to make handling easier and therefore reduce shipping costs. Hydraulic systems for baling are preferred to screw-type balers. Some shrinkage may occur during shipment, probably mainly due to moisture losses.
Originally, all "Eucheuma" produced (including cultured Kappaphycus) was exported as raw material (dried seaweed) to processors in Europe and the United States. From 1978 on, however, carrageenan has been produced in the Philippines in different qualities and amounts, and similar activities started in Indonesia in 1988.
Genetic resources
Material of the "Tambalang" variety of K. alvarezii was brought to Hawaii in 1971 from Mr Alvarez's farm in Calatagan (Batangas Province, the Philippines). The original stock came from Sitangkai (Tawi Tawi Province, the Philippines). It has prospered locally in Hawaii but has hardly spread from the sites where it was planted. The Hawaiian populations have served as a source for many of the other Pacific distributions including laboratory use in the United States (California) and Japan. It is known to have been transplanted by human endeavours and outplanted in many locations including in Indonesia. Branch, micropropagule and tissue culture, as well as clonal propagation from callus of K. alvarezii have been performed successfully.
Breeding
A significantly better-producing variety ("Tambalang") of K. alvarezii was found through a selection programme involving 23 strains and species of the "Eucheuma cottonii" group. Another method of potential strain selection, based on tetraspore progeny within K. alvarezii, has recently been suggested.
Prospects
The carrageenan industry is closely linked to the food processing industry. Future growth should be steady, if unspectacular. Progress may lie in achieving cost reduction in processing, and in developing more versatile and better quality-controlled products.
It is expected that the production of raw material of K. alvarezii in Vietnam might increase dramatically over the next few years. Moreover, for Indonesia it is calculated that the potential area for "Eucheuma culture" (probably including Kappaphycus culture as well) may be 9000-10 000 ha, with an annual production capacity of 45 000 t (dry weight).
The culture of Eucheumoid algae for carrageenan production is only economically viable due to low labour costs. In the main production areas farm productivity is dropping because of declining daily growth rates and susceptibility to stress and "ice-ice" disease, which might be due to prolonged vegetative propagation. There is a need for selection and breeding of new strains. Cultivation of K. alvarezii in cages, together with carnivorous finfish, is a promising practice but still little used. Intensive "Eucheuma" farming may have an impact on the global climate due to the daily production of volatile hydrocarbons (VHC).
Literature
- Azanza-Corrales, R., Mamauag, S.S., Alfiler, E. & Orolfo, M.J., 1992. Reproduction in Eucheuma denticulatum (Burman) Collins and Hervey and Kappaphycus alvarezii (Doty) Doty farmed in Danajon Reef, Philippines. Aquaculture 103: 29-34.
- Dawes, C.J., Lluisma, A.O. & Trono Jr, G.C., 1994. Laboratory and field growth studies of commercial strains of Eucheuma denticulatum and Kappaphycus alvarezii in the Philippines. Journal of Applied Phycology 6: 21-24.
- de Paula, E.J., Lima Pereira, R.T. & Ohno, M., 1999. Strain selection in Kappaphycus alvarezii var. alvarezii (Solieriaceae, Rhodophyta) using tetraspore progeny. Journal of Applied Phycology 11: 111-121.
- Doty, M.S., 1988. Prodromus ad systematica Eucheumatoideorum: a tribe of commercial seaweeds related to Eucheuma (Solieriaceae, Gigartinales). In: Abbott, I.A. (Editor): Taxonomy of economic seaweeds 2. pp. 172-184.
- Doty, M.S. & Norris, J.N., 1985. Eucheuma species (Solieriaceae, Rhodophyta) that are major sources of carrageenan. In: Abbott, I.A. & Norris, J.N. (Editors): Taxonomy of economic seaweeds 1. pp. 47-61.
- Ganzon-Fortes, E.T., Azanza-Corrales, R. & Aliaza, T., 1993. Comparison of photosynthetic responses of healthy and "diseased" Kappaphycus alvarezii (Doty) Doty using P vs I curve. Botanica Marina 36: 503-506.
- Largo, D.B., Fukami, K. & Nishijima, T., 1999. Time-dependent attachment mechanism of bacterial pathogen during ice-ice infection in Kappaphycus alvarezii (Gigartinales, Rhodophyta). Journal of Applied Phycology 11: 129-136.
- Luxton, D.M., 1993. Aspects of the farming and processing of Kappaphycus and Eucheuma in Indonesia. Hydrobiologia 260/261: 365-371.
- Santos, G.A., 1989. Carrageenans of species of Eucheuma J. Agardh and Kappaphycus Doty (Solieriaceae, Rhodophyta). Aquatic Botany 36: 55-67.
- Trono Jr, G.C., 1993. Eucheuma and Kappaphycus: taxonomy and cultivation. In: Ohno, M. & Critchley, A.T. (Editors): Seaweed cultivation and marine ranching. 1st Edition. Japan International Cooperation Agency, Yokosuka, Japan. pp. 75-88.
Sources of illustration
Ganzon-Fortes, E., 1990. Taxonomy of the farmed Philippine Euchema: what's in a name? SICEN Newsletter 1(1): fig. 2, p. 3 (habit); Xia, B. & Zhang, J., 1999. Flora algarum marinarum sinicarum, vol. 2, Rhodophyta, 5. Academiae Sinicae Edita, Beijing, China. Fig. 74, p. 126 (sections). Redrawn and adapted by P. Verheij-Hayes.
Authors
- W.S. Atmadja
