18. The participants presented the results of the country studies, highlighting the species identified, their ecology and the yield and quality of agar. Abstracts of the country reports are presented below:
The full country reports appear as Annex II-l to II-9.
19. Bangladesh: Bimonthly sampling of seaweed was carried out in the coastal area of Bangladesh during: July, September and November 1992; January, March and May, 1993; and July and September 1994. Gracilaria spp. was not found during the period of study. Data regarding ecological conditions were presented. Among 19 different groups of seaweeds collected, most of them were found only from November to March and Asparagopsis taxiformis, Hypnea spp. and Sargassum spp. were most abundant. Agar extraction from A. taxiformis showed that the lowest yield (4.23% ± 0.70) was obtained during January and the highest (12.70% ± 0.53) was obtained during March. The report recommends the introduction of Gracilaria spp. from neighbouring countries for the specific purpose of improving water quality in shrimp culture farms and managing and exploiting existing resources of Hypnea spp. and Sargassum spp.
20. China: In 1993, China produced 450 tonnes of agar, 260 tonnes of which came from Gracilaria spp. More than half the agar produced is consumed locally. Gracilaria is cultured in Hainan, Guangdong and Fujian, with Hainan as the major producer. Twenty-eight species of Gracilaria have previously been reported. The present study concentrated on G. lemaneiformis, G. asiatica and G. tenuistipitata. Within the limited time available, ecological conditions (mainly salinity and temperature) of the various species (including varieties in some cases, as in G. tenuistipitata) were correlated with extracted agar yield and quality. The measured agar content was high and gel strength was good (<500–608 g/cm2). Different methods of extracting agar were compared. No species is specifically prioritised for culture, but the three species described are being cultured. As the study was limited in time (June-September 1994), further study is recommended.
21. India: Studies were made on the yield and physical properties of agar from Gracilaria corticata var. corticata, G. corticata var. cylindrica, G. crassa and G. edulis, growing in four localities near Mandapam. The quality of agar (gel strength) obtained from G. edulis is higher than the other three species, but the yield of agar in this species is slightly less than that in G. corticata var. corticata and G. corticata var. cylindrica. This may be due to the repeated commercial harvesting of G. edulis in the study area during recent years. There were no marked variations in the data collected on environmental and hydrological parameters from the four study areas as all of them are located in the vicinity of Mandapam.
22. Thirty two species of Gracilaria have already been reported from Indian waters and their occurrence in different parts of the Indian coast were described. Descriptions and ecology of four species of Gracilaria (G. edulis, G. corticata var. corticata, G. corticata var. cylindrica and G. crassa) were also given. Studies carried out on seasonal variations in growth, spore output, agar processing, yield and physical properties of agar of Gracilaria spp., Gelidiella acerosa and Gracilariopsis sjoestedtii by different workers, were reviewed. The results of work carried out on experimental cultivation of Gracilaria spp. in different field environments using various culture techniques were given. It was recommended that G. edulis be selected for commercial scale cultivation in India because of its high yield and good quality agar.
23. Indonesia: Five species of Gracilaria, namely: G. edulis, G. lemaneiformis, G. salicornia, G. eucheumoides and Gracilaria sp., were studied. The first two occur more commonly and also yield good quality agar (565–880 g/cm2, gel strength). Most of the species have low gelling temperatures, which is an important characteristic of agar quality preferred for microbiological medium. The study recommends G. edulis and G. lemaneiformis, which have robust thallus and higher biomass production, for culture in both pond and field areas.
24. Malaysia: Studies were undertaken to determine suitable Gracilaria species for culture. Specimens were collected from five locations throughout the west coast of Peninsular Malaysia. Physical parameters for each location were noted. The samples were brought back to the laboratory for preparation of the herbarium specimens and agar yield analysis. Agar extraction was carried out using the hot water technique. The results showed that Gracilaria changii has the following desirable characteristics for culture purposes, namely: high yield and quality of agar; abundant in many locations; euryhaline (22–32 ppt); rapid growth rate; and easily cultured, either using vegetative cuttings or spores. It was recommended that Gracilaria changii be given the highest priority for culture in Malaysia.
25. Myanmar: Taxonomic studies identified seven species, namely: G. verrucosa (Hudson); G. edulis (Gmelin) Silva; G. crassa (Harvey) J. Agardh; G.foliifera (Forsskal) Boergesen; G. millardetii (Montagne) J. Agardh; G. textorii Suringer; and G. eucheumoides Harvey. The first six were studied for yield and agar quality. Four species, namely: G. crassa; G.foliifera; G. verrucosa; and G. edulis were cultured in a small-scale experimental system. The results of the culture experiment showed G. edulis to be most promising. The study recommends its culture in inland ponds and coastal waters. Identification of the species reported as “verrucosa” is not confirmed.
26. Philippines: Results of taxonomic and ecological studies were reported for eleven species, namely: G. arcuata; G. changii; G. edulis; G. eucheumoides; G. firma; G. gigas; G. heteroclada; G. lemaneiformis; G. manilaensis; G. salicornia; and G. tenuistipitata, identified from the materials collected in Philippine waters between June 1992 and December 1994. Collection sites were located in several areas in eight provinces of the Philippines, namely: Cagayan, La Union, Cavite and Sorsogon in Luzon Island; Aklan Samar and Bohol in the Visayas region; and Sulu (Tawi-Tawi and Sitankai) in Southern Mindanao. Of the species reported, five (G. changii, G. edulis, G. firma, G. heteroclada and G. tenuistipitata) have been identified as potential species for farming, based on the quality of their phycocolloid as well as a number of ecological considerations. Of these five, G. firma, G. heteroclada and G. tenuistipitata were recommended as priority culture species considering their wide distribution in the country.
27. Laboratory analysis of the colloid extracts showed that the mean yield was between 16.2% and 24.7%, with G. tenuistipitata obtaining the lowest yield and G. changii the highest yield. Gel strength was highest in G. heteroclada (892 g/cm2) and lowest in G. edulis (250 g/cm2). Gel strength values obtained for the other species were 726 g/cm2 for G. tenuistipitata, 606 g/cm2 for G. firma, 583 g/cm for G. changii and 287 g/ cm2 for G. salicornia. The melting temperature of agar ranged from 79°C in G. edulis to as high as 92°C in G. firma. Most of the species showed high-quality agar that can be used for bacto-agar and agarose production. The report included a discussion of the present status of the country's seaweed industry and a brief review of previous related studies on Philippine Gracilaria spp.
28. Thailand: Seven species were studied for their taxonomy and ecology, namely: G. changii, G. edulis, G. firma, G. fisheri, G. irregularis, G. salicornia, and G. tenuistipitata. In terms of agar quality, G. fisheri and G. tenuistipitata had the highest gel strength of 768 and 758 g/cm2, respectively. This is in accord with the results reported by Dr. Suwalee Chandrkrachang of BRU, that G. fisheri from Songkhla and G. tenuistipitata from Pattani have the highest potential as sources of agar in Thailand. It was recommended that further studies be conducted on these two species with a view to developing them as the main sources of agar for the processing industry.
29. Vietnam: During this study, eight Gracilaria species of the thirteen reported by Nguyen Hun Dinh and Nguyen Ban Tien (1992) were identified from specimens collected in Northern Vietnam, namely: G. asiatica Chang et Xia; G. tenuistipitata Chang et Xia; G. blodgettii Harvey; G. arcuata Zand.; G. hainanensis Chang et Xia; G. chorda Holm.; G. gigas Harv.; and G. bursa-pastoris (Gmelin) Silva.
30. Taxonomic identification of Gracilaria species usually meets with the following difficulties: the variability among species is not clearly seen; morphological features of the species are influenced by environmental conditions and tend to change at different locations; and some of the specimens collected lacked reproductive organs. For this reason, synonyms are often used. Among the above species, four were determined to have high economic value. Of these four species, three were studied and cultivated, namely: Gracilaria asiatica; G. blodgettii; and G. tenuistipitata. The fourth, G. chorda, will also be studied in trial cultivation.
31. Analysis of results from six Gracilaria species collected from Hai Phong and Quang Ninh showed that the dried/fresh ratio, agar yield and gel strength are highest in Gracilaria asiatica. It had also the lowest ash content and is a widely distributed species in Vietnam. It could be cultivated in the brackish water swamps of the Northern region. The other highly promising species for cultivation and agar processing in Vietnam are G. blodgettii and G. tenuistipitata.
Status reports of other governments
The presentations from other governments appear as Annex 11-10 and 11-11.
32. Iran: The representative from Iran reported the studies done on inter-tidal algae in the Southern Coasts of Iran along the Oman Sea and Persian Gulf. A number of surveys and studies have been carried out to identify and map the distribution of Iranian coastal algae. The first attempt to identify algae in the Persian Gulf was made by Diesing and Eadlicher in 1845. The results of this study were confirmed by Borgesean and Koie (1939) and Newton (1955).
33. During four study trips in 1993, 23 species of brown algae, 16 species of green algae and 29 species of red algae were identified in coasts of Persian Gulf and Oman Sea. Sargassum sp., Ulva lactuca, Chondrus crispus species in Oman Sea and Padina spp., Enteromorpha intestinalis, Chondrus crispus species were quite well distributed in the Persian Gulf. The Iranian Fisheries Company has a programme to develop the culture of economic and commercial algal species in Iranian waters and establish a seaweed processing industry based on agar, alginate and carrageenan. Any co-operation with relevant companies and organisations would be accepted and appreciated.
34. Sri Lanka: There are nearly 260 species of seaweeds growing along the Sri Lankan coast, which is some 1700 km long. Gracilaria spp. is the most commonly used seaweed for food. Two species, G. verrucosa and G. edulis occur in commercially valuable quantities in Sri Lanka. Gracilaria edulis was reported in 1950's in the Kalpitiya area. The presence of larger quantities of G. verrucosa (G. confervoides) has been recorded in Koddiyar Bay near Trincomalee. Recent studies have shown that G. edulis gives the highest constitution (48.7%) of best quality agar when extracted at pH 5. Comparison of cultured and wild seaweeds showed that the latter give satisfactory gel content, strength, moisture content, ash content and insoluble ash contents. Comparative studies on three of the most common species found in the northern part of Sri Lanka, namely Hypnea sp., Gracilaria lichenoides and Gelidium sp. have shown a seasonal variation in agar content in these species, the plant showing the highest agar content in January.
35. Sri Lanka used to export an average of 100 tonnes/year of dried raw Gracilaria, but exports have dwindled through the years for various reasons. At present, exporting companies are reporting a very high renewed demand for agar, which they find difficult to satisfy. The National Aquatic Resources Agency launched a project in 1988 at Kalpitiya (north west coast) to find out optimum growth conditions and best culture sites for G. edulis in Puttalam lagoon. Two methods were followed for the cultivation, namely vegetative and spore setting techniques. The culture of Gracilaria spp. on a commercial scale and improvement of processing methods were considered to be of immense importance to national development from seaweed products and have cut down the import expenditure on refined agar.
36. Summary of the results of the country studies. At a pre-workshop meeting of the resource persons, held in Bangkok from 21–23 January, 1995, the findings of the country papers were discussed and summarised. Comments were made on the taxonomy, ecology and distribution of Gracilaria spp. in the region and the results of the agar analysis from each country are presented. The agar extraction methods used in each country were also presented..
The Summary of Results of the Country Papers appear as Annex III.
