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Recent developments in the seaweed aquaculture industries of Pacific islands are reviewed from the perspective of technical, production, geographic, marketing, species-diversification, socio-economic and institutional-support advances. Successful commercial aquaculture of seaweeds in the Pacific island region is presently based on two species, in Kiribati, Fiji and Solomon Islands, and sp. in Tonga. It is possible that other candidate species could be considered for aquaculture for food (e.g. or ) or extraction of agar (), although further research on the technical feasibility of aquaculture methods to produce sufficient tonnage, and particularly on their marketing, is needed. While the Pacific island region may be environmentally ideal for seaweed aquaculture, the limitations of distance from main centres and distance from markets, vulnerability to world price fluctuations, and socio-economic issues, make it unlikely that the Pacific Island region will ever rival the scale of Asian seaweed production. Regional seaweed farming can nevertheless make a useful contribution to supplement other sources of income, and can be an important economic boost for isolated outer islands where few alternative income-generating opportunities exist.

Outdoor tank cultivation of several (nori) species was carried out from late November 2002 through early May 2003 using 40 L (with a surface of 0.25m), 600 L (1m), and 24,000 L (30m) fiberglass or PVC tanks provided with continuous aeration and seawater flow. Sexual and asexual spores produced from cultured conchocelis and frozen thalli in the laboratory, respectively, were subsequently grown to produce young fronds (ca. 5–10 cm) in an average time of 8 weeks. Growth in outdoor tanks and ponds was possible for a period of up to 20 weeks (i.e. growth season), with yields above 100 gFWm d occurring during 12–14 weeks from late December through late March, when seawater temperatures were below 20 °C. These yields correlated with the species and depended on the type of tanks in which the algae were cultivated, with the highest yields observed for sp. and when fertilized twice a week with NHCl and NaHPO in 40 L tanks. Calculations of productivity for an entire growth season based on ≥100gFWm d yields exceed the average productivities using seeded nets in open sea, for all species tested (0.96–4.06 kgDWm season vs. 0.7–1.0 kg DW m of net season). Therefore, tank cultivation of can offer an additional source of nori biomass to international markets. Land-based tank cultivation also offers an environmentally friendly practice that allows for the manipulation of growth conditions to enrich seaweeds with specific, valuable chemicals such as protein and minerals.

The literature on economic feasibility of farming seaweeds like in tropical locations is mainly based upon Asian case studies, and often does not take into account social factors in seaweed farming success. Pacific island countries are culturally and economically distinct from Asia, and efforts are now being made to establish seaweed industries here. Past experiences have showed that social factors often outweigh technical factors in determining the success of rural development projects. In addition, Pacific island communities are very diverse in their socio-economic make-up. The particular community chosen for location of a development project is therefore critical to success. Project managers need to recognize in advance the best type of community for seaweed farming development. The objective of this study was to identify socio economic factors that can be used as predictors of project success or failure. Using results of social survey techniques carried out in eight communities within the Fiji Group, a rapid survey technique has been developed which can enable decisions about whether a community is suitable for farming seaweed or not. Though developed from Fiji case studies, the technique can be applied in other rural Asia/Pacific situations.

is a brown alga recently introduced to the seaweed cultivation industry in Korea. There is current interest in the commercial scale of aquaculture of this species. For the artificial seeding and cultivation of this alga, growth and maturation were investigated from September 2002 to August 2003. Indoor culture experiments for maturation induction were also conducted at temperatures of 5, 10, 15, 20 and 25 °C and irradiances of 20, 50, 80 and 100 mol photons m s under 16:8 h (L:D) photoperiod. Within a given culture test range, higher temperature and irradiance levels favoured the maturation of receptacles in . Using temperature and irradiance control for thalli, artificial seed production of this species could be done one month earlier than thalli matured in nature. Under natural condition, receptacle formation of the plants began in February, and the eggs were released from March to April. For mature thalli of 200 g wet wt., artificial seeding was complete enough for attachment on seed strings of 100 m. Mean production obtained from the artificial seeding technique was 3.0 kg wet wt m of culture rope during the cultivation period.

This study explores the potential cultivation of the giant kelp (L.) C.A. Agardh in southern Chile, for the development of novel food products. The study demonstrates the importance of considering the collection site of the parent sporophytes for successful cultivation. This study also shows that the ropes must be seeded with 10,000 to 40,000 spores ml, depending on the culture method used. We also demonstrated that under environmental conditions in southern Chile, the seeded ropes must be put at sea at the latest during autumn (April) in order to reach the harvesting season in December. However, several other management aspects must be considered to improve the quality of the product. Our final estimation indicates that over 14.4 kg m of rope (fresh weight) can be produced and from this total production, over 70% can reach the quality to produce different food products that are already being introduced in oriental countries. The remaining 30% can be used for abalone feeding and is also available for the organic fertilizer industry located in Chile.

Effects of temperature and salinity on the growth of the two agarophytes, (Hudson) Papenfuss and Holmes were examined in Korea. Both species grew over a wide range of temperatures (10–30 °C) and salinities (5–35‰), and grew well at 17–30 °C and a salinity of 15–30‰. In culture, grew faster than and their maximum growth rates were 4.95% day (30 °C, 25‰) and 4.47% day (at 25 °C, 25‰), respectively. In the field population the maximum growth and fertility of were observed in summer. The growth rate of was slightly higher than that of for 2 weeks on the cultivation rope and in culture but it was much lower after being contaminated with epiphytes. The biomass of the epiphytes was 0.82 g dry wt. per host plant in and 0.001 g in . exhibited resistance to epiphytism and grew 7 times in length and the dry weight increased 15 times after 55 days. In conclusion, appears to be a good agarophyte with a fast growth rate and resistance to epiphytism, and compared with , has good potential for commercial cultivation.

Tanaka & Pham-Hoang Ho (Bangiales, Rhodophyta) is a tropical seaweed collected from the west coast of India. Thalli of the blade phase are found growing only during the rainy season between July and September. They grow on rocky intertidal or subtidal substrata or as epiphytes on other seaweeds such as and . The gametophytic thallus is monostromatic and covered with spines at the base. The species is monoecious. Male gametangia are found in patches that are distributed in the upper part of the thallus. Archeospores are found at the thallus margins and give rise to the blade phase after one week of germination even at 30°C. Zygotospores germinated at 25°C into conchocelis within three days from the date of their inoculation. Conchospores were released at 30°C. The young blades grew at 32°C in the laboratory.

The attachment of spores to a substratum is essential for their germination and, therefore, to the completion of the life cycle of the red algae. In most red algae, spores are liberated without a cell wall, within a sheath of mucilage which is responsible for their primary attachment. Utilizing fluorescent-labeled lectins, we identified carbohydrate residues and their locations in the mucilage and cell walls of spores of . Cell wall formation and mucilage composition were studied with calcofluor, toluidine blue — O (AT-O), alcian blue (AB) and periodic acid-Schiff (PAS). In the mucilage we identified -D mannose, -D glucose, -D-galactose, N-acetyl-glucosamine and N-acetyl-galactosamine. The first two sugar residues were not found in the cell wall of the germ tube but they were present on the rhizoid’s cell wall indicating their importance to substrate adhesion. A cell wall is produced soon after the spore’s attachment, beginning with a polar deposition of cellulose and its gradual spread around the spore as indicated by calcofluor. The cell wall matrix was positive to AB and metachromatic to AT-O, indicating acidic polysaccharides, while cellulose microfibrills were positive to PAS. A polar disorganization of the cell wall triggers the process of germination. As spores are the natural form of propagation of , the understanding of the mechanisms of spore attachment may contribute to the cultivation of this valuable seaweed.

is a fungal pathogen responsible for red rot disease of the seaweed (Rhodophyta). Infection forecasts of by were estimated from the epidemiological observations of thalli and numbers of zoospore of in laboratory and cultivation areas. Four features of forecasting infections were determined by relating zoospore concentrations to the incidence of thallus infection; infection (in more than 1000 zoospores L), microscopic infection [less than 2mm in diameter of lesion (in from 2000 to 3000 zoospores L)], macroscopic infection [more than 2mm in diameter of lesion (in from 3000 to 4000 zoospores L), and thallus disintegration (in more than 4000 zoospores L). High zoospore concentrations led to more infection. The tendency that zoospore concentration of increased with the rate of infection of thalli was generally observed in forecasting infections in both the laboratory and in cultivation areas. Based on the cultivation areas, the accuracy and consistency of forecasting infections suggest that this method could be employed to manage and control red rot disease.

This paper describes the occurrence of an epiphyte infestation of farms in Calaguas Is. Camarines Norte, Philippines. In particular, percentage cover of ‘goose bump’- and ‘ice-ice’ disease, and some environmental parameters that influence the thallus condition of in Calaguas Is. were assessed during 3 separate visits and are discussed.

Commercial cultivation of at Calaguas Is. began in the early 1990s. After five years of farming, the stock was destroyed by a strong typhoon. The area was re-planted the following year and production increased annually and reached its peak in 1998-1999. However, the following year, the first occurrence of a epiphyte infestation occurred concurrently with an ‘ice-ice’ disease. Consequently, annual production and the number of seaweed planters declined rapidly, and this situation persists to the present time. This paper highlights the etiological factors and their consequences.

Results show that farm-site selection is critical for the success of production. Characteristics of water movement and light intensity in farming areas contributed to the occurrence and detrimental effect of the phenomenon described as ‘goose bumps’: a morphological distortion of the host seaweed due to the presence of a sp. epiphyte. A strong inverse correlation was observed between the occurrence of and water movement: areas with low water motion registered a higher % cover (65%) of than those in more exposed areas (17%). Although ‘goose bump’- infestation and ‘ice-ice’ disease pose a tremendous problem to the seaweed farmers, the results of this limited assessment provide a useful baseline for future work.