Light emitting diode (LED) technology has significant potential advantages over other light sources in algal aquaculture. This study investigated LEDs as light sources for the culture of Gracilaria tikvahiae. We cultured a wild-type and a green mutant strain of G. tikvahiae, comparing growth rate and tissue chlorophyll a, total carotenoids, and phycobiliprotein concentrations under high output cool white fluorescent, pure primary color LED, and mixed LED lighting. Under monochromatic light, the growth rates under high output cool white fluorescent lighting were significantly higher than rates under pure LED light (all three colors for wild strain and green and blue for green mutant). However, when pure color LED lighting was mixed (50%/50%), the red + green (wild-type strain and green mutant) and the green + blue LED combinations (wild-type only) showed growth rates similar to those under high output cool white fluorescent lighting. In the trichromatic experiment, growth of the wild-type strain under mixed three-color (40%/40%/20%) LED light was indistinguishable from those of the fluorescent control lighting. Chlorophyll a and carotenoid concentrations of Gracilaria grown in the dichromatic light experiment were 55% and 74% higher, respectively, under red + blue LED lighting than under the other light treatments. The wild-type strain of G. tikvahiae possessed significantly greater concentrations of chlorophyll a, and phycoerythrin than did the green mutant, while green mutant thalli had higher phycocyanin levels. With rising LED efficiency and energy savings, LEDs will be an increasingly better choice for indoor seaweed cultivation, especially if control of pigment production and morphogenesis by selective use of particular wavelengths is desirable.
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Growth rate determinations of the Thai agarophytes, Gracilaria fisheri (Xia et Abbott) Abbott, Zhang et Xia and G. tenuistipitata Chang et Xia var. liui Chang et Xia, were conducted by monoline method in natural earthen ponds (800 m2 in area) using shrimp pond effluents (PI) and ambient seawater (P2), from January 1998 to July 1999. Generally, plants of both species cultured in PI showed a better growth rate and total production than those cultured in P2. Growth rates and total production of the Gracilaria cultured in PI increased in the rainy months and reached a maximum value on.08 ± 1.14% d-I for G.fisheri and 2.68 ± 1.76% d-I for G. tenuistipitata in January 1999. In contrast, growth of both species cultured in P2, projected a slight change in their growth rates, with a maximum value of 1.85 ± 1.00% d-I for G.fisheri and 1.70 ± 0.49% d- 1 for G. tenuistipitata attained in the rainy period (August 1998). All plants of G. tenuistipitata declined drastically in the following dry season. Total production of G. fisheri and G. tenuistipitata cultured in PI showed the highest value of 1000 g wet wt and 961 g wet wt in January 1999, respectively. Plants of both species showed fluctuation in growth and total production, depending on specific cultured conditions of each pond, algal strain used, and on the season. The results suggest that G. fisheri can be grown all year round and is more suitable than G. tenuistipitata for earthen pond cultivation using shrimp pond effluents.
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Growth and fruiting behaviour of the populations of Gracilaria edulis, Gracilaria foliifera and Gracilariopsis sjoestedtii are described based on the field studies conducted from January 1969 to June 1971 in the Palk Bay near Rameswaram. Populations of these three agar-yielding red algae have been observed throughout the year with two half yearly growth cycles, one from October/ November to April and the other from May/June to September. The rale of growth was found to vary in the growth cycles. Plants with reproductive structures occur in Gracilaria edulis and Gracilaria foliifera in all months of the year and in Gracilariopsis sjoestedtii for a short period from November to March. Variations observed in the abundance of sexual, asexual and sterile plants and the abnormal features noticed in the reproductive behaviour of these three algae have been discussed.
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The study was conducted at RTC-Korea-Philippines Vocational Training Center Davao, Buhisan, Tibungco, Davao City from March to May 2017 to determine the growth performance of carrots in terms of number of leaves and leaf stalks as supplied with different levels of Kappaphycus alvarezii drippings at 10 ml, 20 ml, and 30 ml per liter of water. Data were statistically analyzed through Randomized Complete Block Design (RCBD) with five (5) treatments replicated three (3) times. The treatments include pure water (T1), a nutrient solution of 10 ml of Kappaphycus alvarezii drippings per liter of water (T2), a 20 ml Kappaphycus alvarezii drippings per liter of water (T3), a 40 ml Kappaphycus alvarezii drippings per liter of water (T4), and a concentration of water and commercial organic foliar fertilizer (T5). Results showed that the application of Kappaphycus alvarezii drippings through subsurface drip irrigation improved the vegetative growth of carrot in terms of the leaf stalk and leaf count at 30, 37, and 45 days after sowing, under greenhouse structure.
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Field cultivation of Gracilaria edulis was carried out in the nearshore areas of Gulf of Mannar and Palk Bay near Mandapam to determine the various environmental factors which affect the growth of this agar yielding seaweed. These culture experiments were conducted in Gulf of Mannar from October to April during the years 1986-89 and in Palk Bay from April to October during the years 1987-88 when the sea was calm at both places. The epiphytes, epifauna, Low light intensity and sedimentation caused by turbulence of water and grazing by fishes were found to be the primary factors hampering the growth of cultured G. edulis. There was no good growth of G. edulis in Palk Bay during the entire period of this study. But in Gulf of Mannar the growth of G. edulis was good between November and March with maximum yield during the months December to February1 March. The suitable period for field cultivation of G. edulis in Gulf of Mannar is from December to March.
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Aquaculture is an industry with the capacity for further growth that can sustainably feed an increasing human population. Sugar kelp (Saccharina latissima) is of particular interest for farmers as a fast-growing species that benefits ecosystems. However, as a new industry in the U.S., farmers interested in growing S. latissima lack data on growth dynamics. To address this gap, we calibrated a Dynamic Energy Budget (DEB) model to data from the literature and a 2-year growth experiment in Rhode Island (U.S.). Environmental variables forcing model dynamics included temperature, irradiance, dissolved inorganic carbon (DIC) concentration, and nitrate and ammonium concentration. The modeled final estimate for S. latissima blade length (cm) was reasonably accurate despite underestimation of early season growth. Carbon limited winter growth due to a low modeled specific relaxation rate (i.e. the light-dependent reactions of photosynthesis) for some model runs; other model runs displayed nitrogen limitation which occasionally led to length overestimation and underestimation due to the degree of interpolation necessary from the field data. The model usage, however, is restricted to S. latissima grown in an aquaculture setting because of assumptions made about tissue loss, summer growth patterns, and reproduction. The results indicate that our mechanistic model for S. latissima captures growth dynamics and blade length at the time of harvest, thus it could be used for spatial predictions of kelp aquaculture production across a range of environmental conditions. The model could be a particularly useful tool for further development of sustainable ocean food production systems in the U.S. involving seaweed.
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To examine the effects of two endophytic algae, Mikrosyphar zosterae (brown alga) and Ulvella ramosa (green alga), on the host Chondrus ocellatus (red alga), culture experiments were conducted. Four treatments were made: endophytefree (Chondrus only), endophyte-M (Chondrus + Mikrosyphar), endophyte-U (Chondrus + Ulvella), and endophytes-M·U (Chondrus + Mikrosyphar + Ulvella). After 3 weeks, the relative growth rates (RGRs) of frond lengths and the number of newly formed bladelets were examined. M. zosterae formed wart-like dots on C. ocellatus fronds, whereas U. ramosa made dark spots. The RGRs of frond lengths of C. ocellatus were significantly greater in the endophyte-free and endophyte-M treatment groups than in the endophyte-U and endophytes-M·U treatment groups, indicating that the growth of host C.ocellatus was inhibited more by the green endophyte U. ramosa than the brown endophyte M. zosterae. The number of newly produced bladelets was greater in the endophyte-U and endophytes-M·U groups than in the endophyte-free and endophyte-M treatment groups. These results indicate that the two endophytes inhibit growth of the host C. ocellatus. The negative effects of U. ramosa on C. ocellatus growth were more severe than those caused by M. zosterae. Furthermore, U. ramosa destroyed the apical meristems of C. ocellatus, whereas M. zosterae did not. On the other hand, C. ocellatus showed compensatory growth in the form of lateral branch production as U. ramosa attacked its apical meristems.
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Maximum development of plants occurs in the intertidal region at Kilakarai, southeast mast of India, during March-April and Jan.-Feb. in (i. arcuara var. orcuara and from Nov. to Feb. in G. corticota var. cylindrica. Tetrasporic plants are abundant almost throughout the year in both algae. Peak shedding of spores occurs during the maximum growth period in G. orcuota var. arcuoro while seasonal variations are not observed in the discharge of spores in G. corricata var. cylindrica. Monthly output of tetraspores and carpospores varies from 43 19 28,291 and from 10 to 40,055 spores g -1 fr wt in G. arcuoro var. orcuaro and G. corricoro var. cylindrica respectively. There is no definite rhythm in diurnal output in these algae.
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Young plants of T. ornata appeared in April and grew to maximum size during October to December. Plants were mostly unbranched between February and June and thereafter branching started reaching maximum during September to November. Reproductive plants were found throughout the year with a peak spore output in November (33810 oospores/plant). There was no periodicity in the liberation of oospores. T. ornate may be harvested during the peak growth period from October to December for the manufacture of alginic acid.
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Observations made for one year on the seasonal changes in growth, reproduction and spore output of Gracilaria foliifem and Gracilariopsis sjoestedtii are given. These red algae occurred only a few months during the year in the area of study. Maximum growth of G. foliifera was during April and of G. sjoestedtii was during September and January-March. Tetrasporophytes were more abundant than carposporophytes in G. foliifera, whereas in G. sjoestedtii carposporophytes occurred more. Maximum outputs of tetraspores and carpospores were recorded on the tirst day, and the period of peak shedding of spores coincided with the peak growth period of these seaweeds. There was, however, no definite rhythm of diurnal spore output.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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