Showing papers on "Kappaphycus alvarezii published in 2001"

Photosynthesis and growth of red and green morphotypes of Kappaphycus alvarezii (Rhodophyta) from the Philippines

Abstract: The effect of photosynthetic available radiation (PAR) levels, light quality, ultraviolet (UV) radiation, and temperature on photosynthesis, growth, and chlorophyll fluorescence was evaluated in red and green morphotypes of the rhodophyte Kappaphycus alvarezii (Doty) Doty under controlled conditions. Chlorophyll a and phycoerythrin (PE) levels were similar in the red and green morphotypes cultured under the same conditions, but phycocyanin (PC) and allophycocyanin (APC) levels were 2-fold greater in the green than in the red morphotype. Pigment characterization indicated that the overexpression of PC and APC masked the red pigmentation in the green morphotype. Maximum photosynthesis and photosynthetic efficiency were similar between the two morphotypes assayed at a wide temperature range, which was reflected in the similar growth rates observed in outdoor culture systems. In the green morphotype, photosynthetic efficiency increased 2-fold relative to the red morphotype when assayed with red light (λ > 600 nm), indicating that photosynthetic characteristics are modified as a result of pigment variation in these morphotypes. Such increase in photosynthetic efficiency in the green morphotype, however, did not result in greater growth rates when cultured under white light. Short exposure to high levels of solar radiation (UV-A + UV-B + PAR), and filtered solar radiation (UV-A + PAR or PAR) decreased effective quantum yield (ΔF/F m′) in both morphotypes. The reduction of ΔF/F m′ values in the red and green morphotypes was accounted for by high levels of PAR and not by the UV-A + UV-B + PAR and UV-A + PAR treatments. Photoinhibition caused by UV-A, UV-B, or PAR was completely reversed within 30 h after incubations. Recovery rates from photoinhibition, however, were significantly reduced in the green morphotype when incubated with UV-B radiation. The results here suggest that the overexpression of pigments do not necessarily increase photosynthesis and growth in these morphotypes.

Circadian rhythm of photosynthetic oxygen evolution in kappaphycus alvarezii (rhodophyta): dependence on light quantity and quality

Abstract: The rate of oxygen evolution of the tropical red alga Kappaphycus alvarezii was measured for 6 days in the laboratory using a computer-aided method for long-term recording. In cool white light Kappaphacus exhibited a robust circadian rhythm of O2 evolution in the irradiance range of 100 to 1000 µmol m-2 s-1. With increasing irradiance the period of the free-running rhythm, tau, decreased in blue and increased in red light, but did not change significantly in green light. The accelerating or slowing action of blue or red light, respectively, points to two photoreceptors used in the light transduction pathway of the circadian oscillator controlling oxygen evolution or the light reactions of photosynthesis in Kappaphycus. No significant changes of tau were observed with increasing irradiance in cool white light, possibly due to the additive, opposing responses caused by blue and red light.

Growth rate of the carrageenophyte Kappaphycus alvarezii (Rhodophyta, Gigartinales) in vitro

Abstract: SUMMARY Unialgal cultures were established trom a 2.5 g branch ot a brown variant ot Kappaphycus alvarezii (Doty) Doty ex P. Silva, with the main objective to produce branches for monthly outplanting in the sea. Ditterent conditions were tested to optimize production ot branches in the laboratory. The best growth was obtained under culture conditions of 25 ± 2°C, 170–210 μmol photons m2 s−1, 14:10 LD photoperiod and salinity 32–35‰. Three culture media (Provasoli,‘F/2’and von Stosch) were tested. Deleterious ettects were observed in branches incubated continuously in full- or halt-strength Provasoli's enriched seawater medium (PES). Exponential growth rates ot about 3% day−1 were obtained using PES, pulse-fed 24 h per week, or other diluted media used continuously (one-quarter strength ‘F/2’and half-strength von Stosch). Laboratory-grown branches with mean weights from 2.97 to 4.25 g were successfully introduced into the sea at Ubatuba, SP, Brazil (23°26.9′S, 45°0.3′W) an area with mean monthly seawater temperature from 20.3 to 28.5°C (extremes: 17.0–31.0°C). Transplantation of branches produced in unialgal culture, as done in the present study, avoids the risk of introduction of unwanted species into new areas.

Impact of ultraviolet-B radiation on a marine red alga Kappaphycus alvarezii (Solieriaceae, Rhodophyta)

Abstract: Kappaphykus alvarezii (Doty) Doty, an exotic alga to Indian waters is one of the best sources of kappa carrageenan. It was cultured and 60 days old algal fragments were subjected to UV-B radiation (280-320 nm) for 30 to 180 minutes, in the laboratory and analysed for pigments and carrageenam content. A gradual decrease in pigment levels, soluble protein content, carrageenan yield, and in the properties of carrageenan was observed as compared to control. More than 150 min exposure to UV-B radiation strongly inhibited pigment accumulation (63.90 to 92.20%), carrageenan yield (21.68 to 33.82%), gel strength (81.17 to 82.90%) and protein (48.42 to 58.20%).

Circadian rhythms and carbon acquisition in the red algae Kappaphycus alvarezii and Eucheuma denticulatum

Abstract: Aspects of carbon and nitrogen metabolism have been studied in two closely related tropical red macroalgae (Rhodophyta) that belong to the commercially important genera Kappaphycus and Eucheuma. Th ...

Developments in seaweed farming in Southeast Asia

Abstract: During the last thirty years, seaweed farming has progressed in the region comprising the Association of Southeast Asian Nations (ASEAN). Farm production reached a high of 146,500 mt of dried seaweeds in 1997 from an initial harvest of 500 mt in 1973. In 1997, the ASEAN region produced about 90% of the world’s production of carrageenophyte seaweed, providing raw materials for the US$350 million world carrageenan market. Two species of carrageenophytes, Kappaphycus alvarezii (=Eucheuma cottonii) and Eucheuma denticulatum (=Eucheuma spinosum), constitute the base of the seaweed industry in the region. K. alvarezii is predominantly farmed in the Philippines and Malaysia while E. denticulatum is dominant in Indonesia. Vegetative propagation is still applied in all farmed species of carrageenophytes, while the monoline method remains the most popular method of farming. Non-traditional farming areas have been established in central and northern Philippines and in Sabah, Malaysia. The culture technology has been developed for Gracilaria sp.; however, no up-to-date reports on production are available. Seaweed farming has become one of the most important sources of livelihood for at least 100,000 coastal families in Southeast Asia, contributing apparently to the reduction of blast and cyanide fishing and to the relative improvement of peace and order in seaweed farming areas. Introduction The seaweed industry in Southeast Asia was first recognized in the Philippines in the mid-1960s when there was an unprecedented commercial harvest of the red algae Eucheuma. Initially, no attempts were made to farm seaweed. From a harvest of 415 mt in 1969 from wild natural growth, seaweed production increased to 1,240 mt in 1996. In the early 1970s, the Philippines first commercial seaweed farming was introduced in Sulu Sea in southern Philippines, but later on, it was adopted in many areas of the southern and central Philippines, particularly in the Sulu archipelago. The expansion of farming carrageenophyte algae led to the introduction of Eucheuma farming in Indonesia. Eucheuma spinosum (=E. denticulatum) was introduced in Bali, Indonesia in 1978 and, in 1985, seedlings of E. cottonii (=Kappaphycus alvarezii) were brought to Bali from the Philippines. During the last thirty years, the seaweed industry has progressed in the ASEAN region. The ASEAN region produced about 90% of the world’s production of carrageenophyte seaweeds providing raw materials for the US$350 million world carrageenan market. The regular cropping system now provides a reliable and sustainable environment-friendly alternative livelihood to coastal communities in the Philippines, Indonesia, and Malaysia. Farm production reached a high of 146,500 mt of dried seaweeds in 1997 from an initial harvest of 500 mt in 1973. Two species of carrageenophytes – K. alvarezii and 99