by
Gavino C. Trono, Jr.1
A review of the status of seaweed culture in the region shows that the degree of success and the resolution of the associated problem are highly dependent on the availability of basic information on the general biology, physiology and genetics of the species concerned and on the application of this knowledge to the development of their culture techniques. The great successes in seaweed culture achieved in such countries as Japan and China are generally attributed to achievements in controlling the biological cycle and satisfying the physiological requirements of the species both in the laboratory and in the field. Thus, in countries where culture systems or technologies are highly sophisticated, production itself becomes much less of a problem than the monitoring and the control of the culture in order to produce high quality crops to make the industry cost effective. On the other hand, in the countries where these basic informations are not yet available, the development of culture techniques in order to enhance production is the major concern.
Although the major seaweed producing countries are well-known for the cultivation of many species of seaweeds, this review will be limited only to species cultivated as major crops in these countries because of the limited informations available on the minor species.
1. PORPHYRA CULTURE
Several species of the genus Porphyra (in Japanese: nori, in Chinese: zicai) are presently cultured commercially in Japan, China, Republic of Korea and to a limited extent in Taiwan. Although the basic culture methods are quite similar as the techniques generally used are primarily based on those developed in Japan, they may differ in certain details because of differences in the requirements of the cultured species and local conditions.
In Japan the success achieved in the nori industry in the past two decades has been due to significant improvements in the production techniques and the development of genetically superior strains. The development of highly productive strains of Porphyra tenera and P. vezoensis through selection and the extension of fast growing and disease resistant populations has resulted in maximum production. Although efforts to produce fast growing, high quality and disease-resistant varieties through hybridization have been undertaken in the past, there has not been any success to date in producing hybrid strains of Porphyra (Imai, 1982). The difficulty has been attributed to the inherent characteristics of the alga such as the low number of chromosomes and the occurrence of fissions in the succeeding generations of thalli. These characteristics are not favorable to hybridization. In cases where hybrids were produced, problems were encountered in their culture.
Very significant developments have been achieved in the production of Porphyra during the past few years in Japan. Among these are:
the expansion of the use of freezing techniques in storing hibi nets seeded with “young buds” for the lengthening of the production season and/or for back-up stocks for replacing diseased nets;
the development of the floating and raft type support systems which facilitated the expansion of the production to deeper and open waters (the original fixed support system limited the production areas to protected, shallow bays); and
the development of culture techniques of free living Conchocelis and the physiological control of conchospore release had made the seeding of the hibi nets very efficient.
Although these improvements in the culture techniques have tremendously contributed to the success of Porphyra production, these advances have also resulted in problems affecting both the farmers and the government. Overproduction which is generally accompanied by low quality has resulted in lower prices. The introduction of improvements in culture and fertilization techniques and the mechanization of post-harvest operations resulted in increased costs of production thus, decreasing the net income of the farmers. The expansion of the nori industry has also resulted in serious problems in the management of coastal areas and brought about a conflict in their utilization for other aquaculture ventures and/or for other purposes. In Japan increasing industrial pollution in protected bays is also becoming a major problem.
In China the knowledge on the biology of Porphyra haitanensis and P. vezoensis and on the physiological requirements of these species (especially in relation to the mass culture of Conchocelis), and the development of techniques in enhancing conchospore production, the timing of their release, improvements in the nursing of young seedlings, the expansion of production to open; less fertile areas using the semi-floating and floating raft support systems together with the development of fertilization techniques using pumps have increased significantly the production of Porphyra.
Because the Porphyra industry in China is relatively young and smaller in magnitude as the nori industry in Japan, it has not yet encountered serious problems related to overproduction and management. Opportunities for the expansion of production in China are great because of the availability of suitable coastal areas for this purpose. At present the emphasis is on increasing production through improvements in the culture techniques and on the solution of problems related to weeds and diseases.
Although the culture of Porphyra is practiced in the Republic of Korea too, very little information is available in the literature on the subject. According to Saito (1978) the slow development of the industry may be primarily due to its dependence on the export markets (that is Japan's) demands. As can be surmised from Saito's report, the local demand for nori has not developed as yet, therefore, production is still low utilizing mainly old techniques.
The development of Porphyra culture in Taiwan is only at its initial stage. The lack of information on the biology of the local species (Porphyra dentata and P. angusta) has been one of the major constraints in its development. However, progress has been attained in the development of culture techniques for the mass culture of Conchocelis and conchospore formation under artificial light and temperature conditions. The seasonality of production due to weather conditions and the long period between the development of Conchocelis and conchospore formation are two of the major problems confronting the development of local Porphyra culture in Taiwan.
2. UNDARIA CULTURE
The Undaria genus (in Japanese: wakame) is cultivated in Japan, the Republic of Korea and China but it is in Japan where its commercial cultivation has almost equal importance to the nori industry.
The thorough knowledge of the biology and the physiological requirements of the two species presently cultured has resulted in the development of culture techniques which made possible the highly successful Undaria industry of Japan today. The understanding of the physiological requirements of Undaria seedlings, that is their temperature, light and nutrient requirement, resulted in the highly controlled tank culture of seedlings in both private and government nurseries. The problems of disease, epiphytism and grazing which seriously affected production earlier have been resolved by the culture of seedlings in nursery tanks. The readily available seedlings have encouraged the expansion of production to deeper and wave-exposed areas through the development of the raft support system. Improvements in the natural production of Undaria through the management of local stocks have also contributed to an increase in its total production.
The improvements in culture techniques, however, have resulted in overproduction of low quality products which seriously affected the net income of farmers. The application of support systems designed for deeper and open sea conditions has also added to the cost of production.
The introduction of the culture techniques from Japan has also resulted in a significant increase in Undaria production in the Republic of Korea. The use of nursery-produced seedlings has increased production from culture which has been estimated to con-tribute 17 to 18 percent to Korea's total production. However, because the projected increase in local demand and exports did not materialize, the oversupply resulted in low prices.
3. LAMINARIA CULTURE
The rapid development in culturing Laminaria (in Japanese: kumbu, in Chinese: haidai) in China has been attributed to important successes in the resolution of production and quality related problems. The development and application of raft culture has extended production to relatively deep, open seas. The problem of low nutrient supply was resolved with the development of spraying and soaking method of fertilization. The problems of sporeling supply and those of epiphytes and weeds which hinder the normal development of young Laminaria plants in the field were resolved when the temperature requirements of the gametophytes and the young sporophytes was determined. This knowledge became the basis of the low temperature method of culturing summer sporelings under controlled, indoor conditions. The availability of hatchery-reared summer sporelings in early autumn provides a significant ecological advantage for the crop over the competing weed species. The introduction of this method has resulted in a 30 to 50 percent increase in the total production (Tseng, 1981). Aside from decreasing the weed problem, the use of the summer sporelings has lengthened the production period by two to three months and benefitted also workers because planting can now be done in autumn when the water temperature is relatively warm.
The problems of low productivity and inferior quality of the product were resolved through the development of highly productive strains with high iodine content through hybridization. Additionally, the understanding of the etiology of diseases provided a basis for the application of preventive measures. Production areas have been expanded towards the southern parts of China through the development of warm-water strains. The success in the development of long distance shipping techniques rendered the sporelings and matured Laminaria available to farther growing areas.
4. GRACILARIA CULTURE
Although the monoculture and polyculture of Gracilaria (in Chinese: jiangli, in Tagalog: gulaman) in ponds became a very successful aquaculture venture during the past decase in Taiwan, not all the problems are solved as yet. According to Chuch and Chen (1982) one of the most pressing problems which restrains the rapid expansion of this venture is the serious competition in the utilization of coastal areas with other aquaculture methods such as finfish and shrimp culture. The southwestern part of Taiwan where Gracilaria culture has been found to be the most successful is fully utilized for these other aquaculture ventures. This problem was partly resolved by the development of a polyculture of Gracilaria with shrimp and tilapia. The latter species are successfully for weed control in the ponds by controlling other seaweed species such as Enteromorpha and Chaetomorpha. Another problem which adversely affects this venture is the seasonal variation of the agar quality in the production. Among the ecological factors which have significant influence on the quality the most important ones are temperature and daylight regimes. The development of strains adapted to different growing areas is a major step toward the resolution of this problem.
5. EUCHEUMA CULTURE
Although the culture Eucheuma (in Tagalog: gozo) has become a major aquaculture industry since the accidental discovery of fast growing varieties, it has also been going through some critical times ever since its initial success in the early 1970s. These problems stem mainly from two major areas of concern, namely; fluctuating prices related to a weak marketing system and the biological problems associated with production.
The highly fluctuating prices are attributed to a buyers market, where prices are usually determined by a few major buyers/exporters (Hollenbeck, 1983). The farmers whose individual production is small, do not have the capability to influence the local prices of the seaweed. Despite the presence of a number of traders which made the local market somewhat competitive, the Eucheuma wholesale market is still dominated by the buyers and prices continue to fluctuate significantly. One of the primary reasons for the unstable prices is the fact that production is concentrated in one major area of the Philippines and any political instability in this area induces speculation on the amount of the expected supply, affecting ultimately the local prices. In addition, there is a tendency among buyers to acquire their stocks in the shortest possible time (ADB/FAO Report, 1983). Increased production is stimulated by buyers through increasing the local prices, these encourage the farmers to overproduce which in turn results in lower prices. Opening up other production areas to prevent speculation and enhancing the capability of the farmers to influence pricing through the formation of cooperatives would increase incentives to production and stabilize prices.
The fluctuation of production brought about by the seasonality in the growth of different varieties, weather disturbances (e.g., typhoons), the occurrence of the So-called “ice-ice” disease and the general decline in the productivity of the cultured varieties have adversely affected the industry, in many occasions resulting in the economic dislocation of farmers. The growth of the different varieties has been demonstrated to vary with the seasons of the year (Trono, 1985, unpublished). Months characterized by low light intensities and warmer water temperatures (June to October) are generally very productive for all the varieties in contrast to months characterized by high light intensities and cooler temperatures (December to February). However, “spinosum”, varieties tend to recover better than “cottonii” varieties during the following months characterized by higher light intensities and warmer temperatures (March to June). The general practice of the farmers of selecting the best looking plants from their harvest to be used as planting material for the next growing season (without considering their inherent seasonality in growth) appears to have further contributed to the slow but continuous decline in the productivity of the different varieties in the farming areas of northern Bohol, central Philippines. The studies of Trono (loc. cit.) also demonstrated that the low quality of the Eucheuma product (which manifests in a low yield of pure carrageenan) is directly related to the health of the crop during harvest. Healthy crops have high recoverable carrageenan content.
Although there are no conclusive evidences, the occurrence of “ice-ice” disease appears to be preceded by conditions of low nutrient regimes. Uyenco et. al. (1981) showed apparent positive correlation between low concentrations of phosphates and the occurrence of the disease. The relationship between the incidence of blooms of other algae with the occurrence of the disease is not well understood. The problem of low production associated with the seasonality in growth may be resolved through proper management such as the planting of the appropriate varieties during certain months of the year. The requirements for such a scheme that is the availability of the appropriate varieties, however, seems to be a formidable, problem which has to be resolved first. Trono (loc. cit.) proposed the establishment of seedling banks in areas having different oceanographic conditions from those in Danajon Reef farms but accessible to the local farmers.
The solution of the disease problem by developing resistant strains through hybridization appears to be slow due to the lack of basic informations on the sexuality of the different varieties. Although the present work on “seed selection” (based on varietal growth performance tests) may result in the production of physiologically superior varieties, the solution of the problem of enhancing growth and resistance to the disease through genetically improved strains is still paramount. The application of genetic engineering methods such as protoplast fusion may be the ultimate solution.
The expansion of production areas to other parts of the Philippines has been constrained by the minimal support to the efforts in locating appropriate sites for farming and is compounded by the unavailability of the right varieties to be utilized for field testing. Although some general criteria for site selection are available, these are mainly guidelines to narrow the choices to a manageable number of sites and the final decision whether to develop a given site to farms should depend on the results of actual field tests using available varieties. The presence of natural population of the species to be cultured is a good indicator of the potentials of an area.
The lack of appropriate varieties and predation are two of the most important problems generally encountered during the initial stage of the development of an area. Although effective control of large and slow moving grazers (such as sea urchins) can be achieved, it is almost impossible to control fast swimming grazers (such as rabbitfish) especially when they graze during the night. The varieties presently used in two major farming areas in the Philippines that is in Sulu and Northern Bohol appear to have developed peculiar ecological characters over the many years they have been cultured in these areas and as there is no information on the physiological requirements of these varieties, the success of introducing these to new areas sometimes becomes a matter of a hit-and-miss process.
6. CAULERPA CULTURE
Problems encountered in the culture of Caulerpa are mainly the seasonality of the production and the low local demand for the product. Being a stenohaline marine alga, its growth is easily affected by lower salinities brought about by rains during the monsoon season. This problem, however, could be minimized by the incorporation of a flow-through system when constructing the ponds to facilitate proper water management, that is maintaining the salinity above 30 ppt. The development of consumer demand has been constrained by high prices in areas far from the center of production. The introduction of Caulerpa culture in areas where it is popular with local people will result in lower prices within the reach of the consumer.
by
Edgardo D. Gomez1 and Rhodora Azanza-Corrales2
1. INTRODUCTION
The rearing of desirable aquatic organisms under controlled condition for their socio-economic benefits is “aquaculture”. Of the different types of “water culture”, “mariculture” or “seafarming” seems to be less developed compared to freshwater and brackishwater culture. These efforts are geared towards the replacement of traditional, almost unmanaged, harvest of natural populations with the most economical culture techniques that will increase production and improve the quality of selected organisms.
Marine organisms presently being commercially grown in “monoculture” (i.e., culture of single species) include: a) finfish, b) shrimp, c) prawn, d) oysters, e) mussels, f) clams, g) scallops, and h) several species of seaweeds. Of the abovementioned, some fishes, shrimps and prawns are the organisms which are sometimes cultured with sea-weeds. Polyculture is a system of rearing two or several compatible animal/s and/or plant species. It remains to be fully utilized in most countries. Perhaps only Japan has made significant advances in this regard. Aside from practical purposes of saving time and space, the system allows for energy or food partitioning or budgeting among the different organisms cultured. Hence, input of nutrient into the system may become unnecessary or may be minimized through proper timing and control of the levels of production of each species involved. To attain this end, the roles of organisms in relation to each other (or ecological niche) should be clear to the culturists. The biology of the organisms involved should also be well studied or defined. For example the roles of seaweeds in relation to the omnivorous, carnivorous or herbivorous animals need to be clarified. How and when the animals will affect the productivity and reproduction of the seaweeds should also be considered. All the basic information must be gathered to effectively manage the more complicated polyculture system.
This lecture presents existing or developing polyculture systems of seaweeds with marine animals in the ASEAN and Asian countries. Polyculture using a) ponds and b) open sea systems are covered. Suggestions are made on the use of other marine organisms for future polyculture systems, Culture of seaweeds incidental to or in relation to culture of fishes are likewise considered.
2. POND POLYCULTURE OF SEAWEEDS WITH MARINE ANIMALS
In developing ponds for polyculture, a decision must be made on what major product is desired. Fish and crustacean culturist do not necessarily desire to produce seaweeds as a crop. On the other hand, seaweed culturists may raise some animals in their ponds as a by-product or secondary product. More often, however, the animals are raised as a management tool in the control of undesirable weed species.
2.1 Gracilaria pond culture
(After Chen, 1976)
Japan, China, Korea, Vietnam, India, Philippines and Taiwan have been practising Gracilaria pond culture usually with shrimp (Penaeus monodon), crab (Scylla serrata) or milk-fish (Chanos chanos). Doty and Fisher (1986, as cited by Trono, 1986), reports that hatchery produced Gracilaria seedlings from spores are more superior in open field culture. The Gracilaria species used for culture are: a) G. “verrucosa”, the preferred species in Taiwan, b) G. lichenoides, c) G. gigas and d) G. compressa.
Chen (1976) enumerated the following ideal pond culture conditions of Gracilaria: a) the rectangular pond, one hectare in size, should not be exposed to strong wind, the long axis perpendicular to the direction of prevailing winds; a windbreak may be constructed on the windward side, b) sufficient tidal flow to change water, c) sandy loam bottom, d) pH of 6–9 preferably 8.2 to 8.7, and e) fresh water available to avoid above normal salinity.
2.1.1 Culture method
Cuttings of Gracilaria can be broadcasted to grow on pond bottom planted in nets fixed on poles, or tide to monoline systems as is being done in Burma. Sporelings can be grown on adobe or cement blocks added to the substratum as in Bacoor, Cavite, Philippines. Average water depth is 60–80 cm. Water is changed once every two to three days and fertilization with 3 kg urea or 120–180 kg fermented manure from pigsties when new water is introduced. The stocking materials and time of harvest for a hectare of farm are as follows (Trono, 1986):
| Organism | Stocking material (kg) | Time of harvest |
| 1. Gracilaria | 4 000 to 5 000 | after 3 mos. |
| 2. Crab | 5 000 to 10 000 | 3 mos. |
| 3. Shrimp | 10 000 to 20 000 | 4–7 mos. |
Milkfish which can be stocked at 500 to 1 000/ha can control the green algae (Enteromorpha and Chaetomorpha) which may be “pests” on Gracilaria. Other weeds include Acanthophora and Bangia. After the green algae are gone, the milkfish will eat Gracilaria. When this begins to happen they should be netted at the water inlet where they congregate.
Many Gracilaria farmers stock Penaeus monodon or Scylla serrata to utilize fully the pond space and for additional income. Net income from this type of polyculture is three times as much as monoculture of the seaweed. Annual production of dual Gracilaria is about 10 000 to 12 000 kg. Drying rates is 1.7. The criteria for maintaining the quality of export may be summarized as follows: not more than one percent mud and sand; not more than one percent of mollusc shell; and not more than 18 percent mixture of other seaweeds: total not more than 20 percent foreign materials. The moisture must not exceed 20 percent. The dried seaweed is packed in 100 kg gunny sacks for export or local sale.
Penaeus monodon tolerates up to 30°C and 10–35 ppt. The stocking density in nursery ponds is 300 000 to 500 000 fry/ha. Later, stocking density is reduced to 10 000 to 12 000 juvenile/ha in grow-out ponds as in polyculture with Gracilaria. “Lab-lab” which is the scum or crust of microbenthic algae that may grow naturally in ponds (on poles or attached to macrobenthic algae such as Gracilaria), serves as feed to the shrimps. Ricebran, dead fish or other protein sources can be ground with “lab-lab” for feeding. Small-scale production of shrimps is usually achieved in this polyculture with Gracilaria.
2.2 Caulerpa pond culture
To date, the Philippines is the only country known to be cultivating Caulerpa in ponds. The more popular species being cultured in Mactan Island, Cebu and lately in Batangas is C. lentillifera. Production of this and other edible Caulerpa species, however, remains to be dependent upon natural stocks. Trono and Denila's (1987) experiments on pond culture of C. lentillifera have shown that: a) there is seasonality in production under farmed and natural conditions; b) seasonality seems to be influenced by salinity primarily and temperature and light intensity secondarily; c) production is better in ponds than in open natural conditions; and d) water management is an important factor for successful farming.
Their experiments have also shown the following growth rates and increase in biomass production in C. lentillifera in pond culture.
| Stocking density | Growth rate | Percent increase |
| 100 g/m2 | 15.16 g/m2/day | 940 percent |
| 250 g/m2 | 19.78 g/m2/day | 478 percent |
| 500 g/m2 | 32.00 g/m2/day | 376 percent |
The conditions in the experimental fish-pond about 1/4 of a hectare size were as follows: a) muddy substratum; b) temperature range of 22.5 to 37.5°C; c) salinity range of 23–36 ‰ (lowest in August highest in March of 1982); and d) light intensity range of 4 500–10 000 lux. Plants were produced by vegetative regeneration of stocks coming from Mactan Island, Cebu.
Although most of the fish and/or shrimp culturists (in Mactan, Cebu) have apparently shifted to monoculture of Caulerpa, some have retained small-scale production of these animals. With proper management, this polyculture system can be continued or enhanced.
3. OPEN SEA POLYCULTURE OF SEAWEEDS WITH MARINE ANIMALS
Eucheuma, Porphyra, Undaria and Laminaria are the seaweed genera which have been successfully cultured in nets or monolines attached to poles in the “open sea”. Systems for their monocultures have been outlined by Trono (1986). Details of their culture techniques are not considered in this paper since they are fully covered by the other lectures.
3.1 Possibility of Eucheuma polyculture with giant clam, abalone or lobster
Eucheuma monoculture in the Philippines is quite extensive. Existing farms are found in Southern Philippines (which has the greatest production), Central Visayas and Batangas. Most of the farmers utilize about one hectare (per family) wherein 10 meters long one meter apart monolines are fixed on the substratum of reef areas. About 35 Eucheuma (30 to 50 g/bunch) cuttings are tied at 20 to 25 cm interval per monoline. Since harvesting of whole plants are usually done monthly when replacements or replanting are done, spaces between mono-lines could be unproductive or useless. Limited numbers of giant clams which do not feed on seaweeds could then be cultured in these areas. Their shells can be substrates to the spores and sporelings of this genus whose thalli have been recently found with tetraspores and carpospores even in farming conditions. However, weeding of other seaweeds that may also grow on the clams should also be done.
Giant clams of the genus Tridacna and Hippopus have been successfully spawned in various laboratories in the Pacific. As a consequence, several species are now being farmed in Australia, Philippines and several countries in South Pacific. Interest in these “self-feeding” bivalve is growing because of its economic value.
Abalones which are herbivores could also be cultured to a limited extent in unproductive sites in a Eucheuma farm. Care and attention should be given so that they will not negatively affect production of sea-weeds. If the primary concern is abalone culture, the organism being quite expensive and in demand as food especially in Japan and Korea, seaweed beds could be maintained or developed for their shelter and protection. Ohno (1987) has been doing experiments to produce seaweed beds from artificial substrates (reefs) for various stages of abalone culture in Japan. In other ASEAN countries like the Philippines, existing sea-weeds beds could be utilized for this purpose.
Spiny lobsters could also be grown in sea-weed beds in the open ocean. It has been found that the planktonic larvae swim into shallow coastal waters to seek shelter in seaweed beds, particularly among those members of Rhodophyta. The juvenile lobster forage on these seaweed (and sea-grass) beds for molluscs and crustaceans. Since availability of feeding areas has been found to limit growth of the young lobsters, special types of artificial structures to generate seaweed: beds are also being built and tested in Japan (Ohno, 1987).
4. CULTURE OF SEAWEEDS IN RELATION TO FISH CULTURE
Seaweeds are now being deliberately grown or cultured in the open sea in order to expand, develop or conserve fishing grounds. In Japan, a “National Scale Fishing Ground Engineering and Development Program” was launched in 1976. Among others, the programme consists of submersion of artificial reefs and breakwaters and creation of seaweed beds and forests. All of these have been done in connection with a “marine ranching program” that will enhance marine fisheries production within the country's territorial limits (Yamane, 1987). These artificial reefs made of cement blocks or steel are used as substrates to develop seaweed beds and forests where other marine organisms could be grown as discussed in the preceding paragraphs. Sea-weed beds or forests made up of Sargassum, Laminaria or Eisennia could serve as spawning or nursing areas for fishes (Ohno, 1987; Tsukidate, 1987). Tsukidate (1987) reports that about 50 spp. of fishes belonging to 23 families have been found along Sargassum masses. These fishes belong more commonly to the following genera: Sebastes, Sebasticus, Hexagrammos and Seriola. Floating or sub-merged seaweeds serve as attachment of microalgae which can be: a) food for fish, b) substrate for their eggs, and c) spawning ground (Kimura, 1987). Japanese fishermen usually catch fishes along or adjacent to floating Sargassum masses (Tsukidate, 1987). Other marine animals found in the seaweed (Sargassum) beds are polychaetes and molluscs at their larval, young and adult stages (Tsukidate, 1987; Ohno, 1987).
In other Asian countries where seaweed beds still flourish, conservation and management of their stocks need to be done or started soon. This is not only to protect the seaweed species from overexploitation but also to maintain these sites as fishing grounds. Polyculture of suitable fishes in available or newly created seaweed beds can be done in countries other than Japan which has initiated the programme.
Incidental culture of seaweeds in cultivation sites of some fishes has also been observed. In the cage and pen culture of yellowtail (Seriola quinqueradiata) in Japan, luxurious growth of Hypnea and Gracilaria has been noted. The culture of seabass (tales calcarifer) in Thailand has also yielded growth of some Gracilaria species.
Fish Attracting Devices (FADs) can also have overgrowths of certain seaweed species. They can be used as structures for seaweed culture. The Philippine “payaw” which makes use of bamboo poles and leaves of terrestrial plants can utilize seaweeds in order to attract fishes more effectively, and culture these marine plants at the same time.
The (over) growth of seaweed species in fish culture areas and FADs can be developed, maintained and controlled to generate secondary products.
REFERENCES
Bardach, J.E., J.H. Ryther and W.O. Mclarney. 1972 Aquaculture. The farming and husbandry of marine organisms. New York: Wiley. Interscience. xii, 688 pp.
Chen, T.P. 1976 Aquaculture practices in Taiwan. Fisheries New Books Ltd., Farnham, Surrey, England, xiii, 162 pp.
Doty, M.S. and J. Fisher. 1986 Experiments with Gracilaria in Hawaii, Hawaii Botanical Science Paper No. 46. University of Hawaii. 486 pp. (as cited by Trono,1986).
Enomoto, Y. (unpubl.). 1987 Outline of aquaculture in Japan. Lecture, Training in Marine Ranching System, Kochi University, Kochi-ken, Japan.33 mimeograph pp.
Gomez, E.D. 1981 Potential for polyculture of Gracilaria with milkfish or crustaceans.Lecture 15. Report on the training course on Gracilaria algae, United Nations Development Programme, Food and Agriculture Organization. Manila, Philippines, April 1–30, 1981. pp. 91–93.
Kimura, H. (unpubl.). 1987 Artificial fish reefs. Lecture, Training in Marine Ranching System, Kochi University, Kochi-ken, Japan. 28 mimeograph pp.
Ohno, M. (unpubl.). 1987 Creating of seaweed bed and artificial structure for spiny lobster and abalone. Lecture, Training in Marine Ranching System, Kochi University, Kochi-ken, Japan.) 19 mimeograph pp. + 6 figs.
Trono, G.C., Jr. 1986 Seaweed culture in the Asia-Pacific Region. Regional Office for Asia and the Pacific (RAPA), Food and Agriculture Organization of the United Nations, Bangkok. 41 pp.
Trono, G.C., Jr. and H.C. Denila. 1987 Studies on pond culture of Caulerpa. Phil. J. Science Special Issue on Marine Science. Monogr. No. 17:83–91.
Tsukidate, J. (unpubl.). 1987 Marine Ranching Program. Lecture, Training in Marine Ranching System, Kochi University, Kochi-ken, Japan. 15 mineograph pp.
Yamane, T. (unpubl.). 1987 A national scale fishing ground development plan by means of artificial reef placement in the sea and its socio-economic effects in Japan.Lecture, Training in Marine Ranching System, Kochi University, Kochi-ken, Japan, 32 mimeograph pp.
by
Edna T. Ganzon-Fortes1
1. INTRODUCTION
To be able to effectively acquaint one's self with the seaweeds, one must experience the collection of the specimens in the field and their preparation in the laboratory for the herbarium. Only through the practice of handling and distinguishing the plants as they appear in nature or as pressed or preserved specimens, can one develop the ease of identifying them. By carefully comparing the specimen with the taxonomic description of the species in the literature may lead to the right identification of the species.
2. COLLECTION OF SEAWEED MATERIALS
The following are the usual supplies and materials necessary for seaweed collection:
booties or rubber shoes
The best time for collecting the seaweeds is during the hours of the falling tide. It is best to go to the collection site one to two hours before the time of the low tide (minus tides are the best times) as predicted by the tide table. This is to allow the collector considerable amount of time to observe the algae in their natural habitat, to record such observations and to collect the specimens.
When collecting, be sure to remove the complete plant (including the holdfast) from the substrate and put this in the plastic bag together with the label which include the place, date of collection, kind of substrate of habitat. Be sure to gather only what is needed for conservation purposes. Delicate or small materials should be placed in separate plastic bags (small) or vials. Many specimens can be removed from their substrates by hand but those closely adhering to rocks such as crustose or mat-forming species may be removed with the help of a knife or any scraping material to secure the complete holdfast. However, those species which may adhere so closely to the rocks can be removed with the rock using a geologist's pick or any similar instrument. For the epiphytic species, this could be collected with a portion and the host plant.
3. PRESERVATION AND TRANSPORT OF SEAWEED MATERIALS
Things needed are the following:
large plastic bags (sack size)
Prepare five percent solution of commercial formalin in sea water. Prepare a stronger solution of 10 percent if the specimens to be fixed could not be processed immediately. Remove all animal components, rocks and other foreign materials from the collected seaweeds. Before addition of the formalin, drain the water from the plastic bag. The formalin should then be poured to the seaweed materials inside the plastic bag in amounts just enough to fill the bottom of the bag. Additional formalin may be added if the materials are bulky or fleshy. The fumes of the formalin.would be enough to fix and preserve the algal materials. All these materials should be properly labelled with information on the place and date of collection, name of the collector and pertinent observations on the character of the habitat written on quality paper or any substitute using indelible ink or pencil. Label also the plastic bags using pentel pen.
For transport of the plastic bags containing the preserved algal materials, these should be placed in large styrofoam boxes or barrels or in two to three layers of good quality large plastic bags (approximately 0.6 × 1.0 m in size) properly tied with rubber band to prevent any leakage of formalin.
4. HERBARIUM TECHNIQUES AND PROCEDURES
Things needed:
strings or any tying material
Upon returning to the laboratory, ready the above materials for preparation of sea-weeds for the herbarium. It would be convenient to work on the individual collecting bags. Dump specimens contained in each bag into a flat-bottom basin containing fresh water to wash off excess formalin and other foreign materials, i.e., sand, pieces of shell, etc. Sort out the seaweeds according to species. Assign a collection number to one species collected in one area at one time. This number should be recorded in a data notebook together with the information on the name of the species, date and place of collection, name of collector and other pertinent ecological data. This same number should be written on the mounting sheet carrying the particular algal species. In mounting, place the paper on top of a flat galvanized sheet and immerse both in a basin of clean water. Arrange the specimen on the mounting sheet while under water to simulate their natural habit, especially when this is of the filamentous type. Then lift the galvanized sheet carefully from one side to allow the water to drain off gradually and to leave the specimen spread out and undisturbed. Final arrangement of the specimen may be made when out of the water with the use of forceps and dissecting needles.
Place the mounting sheet with the specimen directly on top of the newspaper which is spread out on the blotter resting on a ventilator. Cover the specimen with a cheese cloth. Then, place another newspaper and blotter on top of the cheese cloth. Add another ventilator on top of the pile. The same process is repeated for the rest of the mounted specimens until a sizeable pile is made. This pile should then be stacked between two wooden pressers. Enough pressure should be applied to the pile while tying it tightly.
The whole stack is left to dry in an oven-dryer under temperature of 65–70°C for 24–32 hours (continuous) or three to four days if oven is “on” only during daytime, depending on the thickness of the pile. If an oven-dryer is not available, frequent changing of the driers (such as the wet blotters, newspapers and cheese cloth) must be done until drying is complete.
For the crustose algal species, these should be dried directly in the air, then kept in small boxes of suitable size. Articulated, calcareous algae that are so fragile/or so three-dimensional as to suffer badly from pressing should also be air-dried and kept in boxes. (Be sure to provide labels to each species in the same way as the mounted ones). They should, however, preferably be soaked for several days or weeks in a formalin solution containing 10 to 40 percent glycerin before being dried and kept in small boxes. Glycerin retains the flexibility of the genicula and prevents fragmentation.
All seaweed specimens (mounted or in boxes) should be provided with labels containing the following information: collection number, name of species, place and date of collection, collector/s and other pertinent ecological data if available. For those materials which do not stick to the mounting sheet use gum arabic glue or any substitute. Keep the seaweed exsiccatae materials (dried herbarium materials) in a cabinet.
5. PREPARATION OF SLIDES OF MARINE BENTHIC ALGAE FOR IDENTIFICATION
5.1 Whole mounts
Microscopic forms of benthic algae especially the epiphytes are always mounted wholly. To prepare temporary mounts, carefully wash the specimen on a petri dish by changing the fresh water several times until the sand or mud particles are removed. Then transfer the specimen to a clean glass slide. Stain it with one percent aqueous aniline blue by adding one to two drops of the stain, acidifying it with one drop of one percent HC1 after about a minute, and then washing it with a drop or two of distilled water. Excess acidified stain and water may be blotted off with tissue paper. Add a drop of glycerin or 45 percent Karo syrup with phenol to the specimen before putting the cover slip. Apply nail polish to seal the edges of the cover slip.
5.2 Cross-section mounts
The sections of the branches may be used for anatomical studies. The freezing micro-tome, if available, is one of the most useful equipment for preparation of sections. However, free hand sectioning may be easily substituted for the microtome although the sections may not be as good. Skill in making sections can be developed through practice.
For materials which are foliose, good sections may be produced by cutting a piece of the blade, then folding this several times and placing it between two glass slides in such a way that a part of the specimen is exposed beyond one end of the upper slide. Use the upper slide as a guide for cutting. Be sure to use new razor blades. The plane of cutting should be tilted towards the far end of the material in such a way that several cuts could be made before the upper slide is slid back a little to expose more of the materials for further cutting. Many of such sections should be made and only the thin ones can be separated from the rest using a dissecting microscope.
For those materials with cylindrical or flattened branches, the same technique can be used. One to several of the branches (depending on the diameter) should be placed between two slides as discussed above.
The sections are stained with aqueous aniline blue using the same procedure described for the “whole mounts”.
5.3 Squash mounts
Materials which are soft and basically filamentous in construction easily lend themselves to this special technique. These may also include those materials which are slightly calcified. These are first decalcified using 10 percent HC1 solution right on the slide. Then remove excess acid using tissue paper as absorbent material. Wash the specimen with distilled water by adding drop by drop of the liquid. Blot off excess liquid with tissue paper.
The same procedure described for the “whole mounts” is followed when staining the squash mounts.
All slides should be labelled; include the collection number, name of the species and structure emphasized in the slide.
