SINTEF, the largest independent research organisation in Scandinavia, has been working for some years to develop a national seaweed culture program. Now SINTEF has established the Norwegian Seaweed Technology Centre in its Fisheries and Aquaculture Institute near Trondheim, Norway. A staff of about a dozen people is devoted to the centre's main objective: the development of commercial-scale cultivation of seaweed for the production of biofuels.
Seaweed is a famous delicacy in some parts of the Asia and also a well-known source of important food hydrocolloids, such as agar, alginates, and carrageenan. In addition to the food value of seaweed, several health benefits have also been reported to be present in this valuable food source. It is presumed that the unique features of the marine environment, where the seaweeds are grown, are mainly responsible for most of its properties.
Among the functional effects of the seaweed, nutritional and health-related benefits have been widely studied. Compared to the terrestrial plants and animal-based foods, seaweed is rich in some health-promoting molecules and materials such as, dietary fiber, o-3 fatty acids, essential amino acids, and vitamins A, B, C, and E. In this chapter, the nutritive value of seaweed and the functional effects of its soluble fiber are discussed with a special reference to the digestive health promotion of human.
The red algae Gracilaria edulis, Hypnea valentiae, Acanthophora spicifera and Sarconema indica have been observed to occur and grow in a culture pond. Over a period of eight months, the algae grew to 104 kg in the pond of 800 sq m. The hydrological conditions in the pond are compared to those in the sea containing natural beds of these algae during the period of observations. This occurenceand growth may open up the possibility of growing thses algae in culture ponds providing the requisite hydrological and nutrient conditions.
The potential of seaweeds as feedstock for oil-based bioproducts was investigated, and the results support seaweeds as a biomass source for oil-based bioproducts. Seaweeds have not traditionally been perceived as a suitable feedstock for oil-based bioproducts because of their low content of lipids and fatty acids. In contrast to this perception the first major outcome of this thesis was the provision of new benchmark species of seaweed for oil-based bioproducts, selected because of their high oil contents combined with high proportions of omega-3 polyunsaturated fatty acids (PUFA(n-3)), which are the target fatty acids for high value products in health and nutrition. The three key species of seaweed identified were Spatoglossum macrodontum, Dictyota bartayresii and Derbesia tenuissima with high total lipid contents (~ 12 % dry weight (dw)) and high total fatty acid contents (4 – 8 % dw). These species also had a high proportion of PUFA(n-3) which were ~ 20 % of total fatty acids (TFA) in S. macrodontum and D. bartayresii and over 30 % of TFA in D. tenuissima. The second major outcome of this thesis was then the identification and quantification of natural variability of fatty acids within the key species of seaweed which can be exploited for further improvements in the content and composition of fatty acids. For S. macrodontum, the content of TFA (55 – 83 mg g⁻¹ dw) and the proportion of PUFA(n-3) (16 – 25 % of TFA) varied substantially (~ 50 %) on a temporal scale. For D. bartayresii, the content of TFA (45 – 55 mg g⁻¹ dw) varied slightly (~ 20%) and the proportion of PUFA(n-3) (16 – 24 % of TFA) varied substantially (~ 50 %) on a temporal scale. There was also spatial variation for D. bartayresii which was ~ 50 % for the content of TFA (36 – 54 mg g⁻¹ dw) but less than 10 % for the proportion of PUFA(n-3) (18 – 20 % of TFA). The third major outcome of this thesis was then the demonstration that environmental parameters are drivers for fatty acid variability in these species. The first line of evidence was from seasonal field-based studies on S. macrodontum and D. bartayresii which showed a higher proportion of PUFA(n-3) in winter when water temperature and light availability were at their annual minimum (~ 40 – 50 % higher in winter). In a second line of experimental evidence for D. tenuissima, colder water temperature was identified as the major driver (explained ~ 40 % of the total variability) to improve the proportion of PUFA(n-3) by ~ 20 % in this species. In a similar manner, high light intensity reduced the quality of the biomass by increasing saturation. The fourth major outcome of this thesis was the identification of a relationship between biotic parameters (plant size and life cycle stage) and fatty acids. In D. bartayresii, plants with a larger thallus length had significantly higher contents of TFA and slightly higher proportions of PUFA(n-3) and in S. macrodontum older plants in their "decline phase" had a more saturated fatty acid profile than younger plants in their "growth phase". Both the environmentally and biotic driven variability in fatty acids can be exploited through culture and harvest strategies to improve the fatty acid content and quality in these feedstocks. The fifth major outcome of this thesis was for the first time the provision of evidence for the genotypic variability of fatty acids within species of seaweed which is the basis for selective breeding to improve the yield of target fatty acids. First, there was substantial spatial variability (~ 40 – 60 %) in the content of fatty acids between the sampling locations of D. bartayresii, suggesting genotypic differences between populations. The second line of evidence was from experimental data on isolates of D. tenuissima where the content of TFA ranged from 34 to 55 mg g⁻¹ dw and 49 % of the variation was genotypic (between isolates). The proportion of PUFA(n-3) ranged from 31 to 46 % of TFA with a strong interactive effect of genotype and water temperature. In two isolates, the proportion of PUFA(n-3) increased by 20 % under cultivation at low temperature while in a third isolate temperature had no effect. Increases in PUFA(n-3) occurred with a stable content of TFA and high growth rates, leading to net increases in PUFA(n-3) productivity in two isolates. And last, the sixth major outcome of this thesis was the identification of fatty acid variability within individual plants. The content of TFA and to a lesser degree in the composition of fatty acids varied substantially within plants of S. macrodontum (TFA: 21 – 106 mg g⁻¹ dw) and D. bartayresii (TFA: 40 – 57 mg g⁻¹ dw) with a higher content of TFA and a higher proportion of PUFA(n-3) in the upper sections compared to the base. Overall, this thesis provides the basic framework on which to develop strategies for the domestication of seaweeds for the production of oil-based bioproducts in a similar manner to the past improvements in the oil yield of terrestrial oil crops and also microalgae. The most important domestication steps identified in this thesis were species selection and permanent improvements in the content and composition of fatty acids through selective breeding with D. tenuissima being the prime target species for this process.
Boergesen (1937) reported Bostrychia tenella (VahI.) J. Ag. from Indian waters. Some details regarding the morphology of the alga are available to some extent by the works of Montagne(1828).Falkenberg (1901). Post (1936). Tseng(1942)and Joly (1954) . The detailed structure of the alga and the development of the reproductive structures are not known completely. Advantage was taken of the occurrence of Bostrychia tenella in the Gulf of Mannar at Mandapam to study the morphology of the species both from living specimans and from material fixed in 4% formalin and forma lin -acetic-alcohol. Suitable preparations were stained in eosine and mounted in glycerine for microscopic examination. Sometimes the material had to be softened by placing in 1 % acetic acid or 1 % lithium chloride solution. While thin sections were used frequantly. most datails could be observed on whole mounts and squashes of suitable pieces of the thallus of the alga.
Saccharina latissima is an economically and ecologically important native kelp. As its limited supply from wild stock cannot meet increasing current and future demands, methods for its cultivation in the ocean need to be developed. This kelp is now beginning to be farmed off the Atlantic coast of Spain using a regular method similar to the “forced cultivation” technique used with Asian kelps (kombu). Its cultivation is also a growing enterprise in other European countries. In this study, the open-sea farming of S. latissima using the transplanting method is tested on a commercial-scale. This cultivation method has not been studied with kelp species outside Asian waters. The tested method includes the following steps: indoor production of seedlings, pre-culture in greenhouse tanks and open-sea cultivation by transplanting young fronds. Results demonstrate that open-sea cultivation using transplanted young fronds is a technically and biologically viable method. The total yield obtained (8.3 kg fresh m−1 rope equivalent to 45.6 ton fresh ha−1 farm) is satisfactory considering the low densities of transplanted fronds (25–30 fronds m−1 rope). Moreover, these values are comparable to those reported in previous cultivations with this species, as well as in the farming of similar kelps. The transplanting method used in conjunction with the regular cultivation method has valuable practical applications for the commercial farming of S. latissima.
Quickly reducing methane emissions is an important strategy for meeting 2050 climate targets because of the powerful radiative forcing of methane and its relatively short lifetime, but this strategy is undermined by rapidly rising emissions. Agriculture contributes around 40-46% of global methane emissions, and because of rising food production, these emissions are on a path to increase roughly 40% by 2050. Of these emissions, two-thirds are from enteric methane from ruminant livestock, roughly 20% are from rice, and 7% are from managed manure. Although mitigation efforts for agriculture have received less attention, we set forth a credible scenario to decrease these emissions by 54% relative to otherwise likely emissions in 2050 and by 36% compared to present emission levels. Mitigation opportunities include: (1) increasing the feed efficiency of ruminant livestock; (2) rapid development and deployment of promising enteric methane inhibitors; (3) realizing an “Optimistic Trend Projection” for consumption of ruminant meat, which relies more heavily on alternative sources of animal protein; (4) deployment of at least one basic water level drawdown in flooded rice fields plus better offseason management of residues; (5) broad use of at least one method of reducing methane emissions from manure managed in wet form; and (6) reductions in global food loss and waste. Other innovative ideas are also promising. To achieve this mitigation, we suggest in the near-term an internationally coordinated effort to develop “shovel-ready” projects using known mitigation options but structured to encourage innovation and to improve our understanding of how to reduce emissions further. We also suggest a series of internationally coordinated R&D projects and demonstration projects of promising technologies. One key need is a $100 million initiative to have multi-year tests of promising enteric methane inhibitors in at least 20 world locations, and related technical work to bring them to market.
India has a long rich bio-diverse coastline that provides livelihood to millions. While traditional aqua farming has helped shape the coastal economy over the years, the country has been rather obtuse in adopting seaweed cultivation, an allied agricultural sector that holds immense prospects for the nation’s economy.
An experiment was conducted in earthen ponds at the Asian Institute of Technology, Thailand to determine different phosphorus fertilizer dose effects on Nile tilapia production, water quality variables, nutrient utilization and cost-benefit under supplemental feeding. Five phosphorus fertil- ization rates were used as treatments e.g. 100%, 75%, 50%, 25% and 0% of 7 kg P ha week1. Nitrogen fertilization rate was fixed at 28 kg N ha week1 for all the treatments. Sex-reversed Nile tilapia were stocked at 3 fish m2, and 30% CP floating feed fed at 50% satiation feeding rate. Nutrient budget showed higher phosphorus fertil- izer input resulted in higher phosphorus sink in the sediment. Mean weight, mean weight gain, daily weight gain and net yield were not signifi- cantly different among treatments (P > 0.05). Total Kjeldahl nitrogen, total phosphorus and sol- uble reactive phosphorus were significantly differ- ent among treatments. Economic analysis showed phosphorus fertilization resulted in positive net returns. Though the gross income was not affected by different fertilization rates, significantly lowest cost was found in the treatment using 25% phos- phorus fertilizer. It can be concluded from the research that 25% phosphorus fertilization might be used as an alternative strategy of Nile tilapia pond culture in terms of economic return and nutrient loss in sediment.
Seaweeds play essential ecological and biogeochemical roles and support important industrial applications. Sustaining natural populations of seaweeds under climate change while simultaneously putting seaweeds to use in climate solutions requires that we weave together disparate lines of inquiry—the ecological and the industrial—to create a more holistic perspective and integrated research agenda. Innovation in the use of seaweeds must be more than aspirational—it requires evidence of effectiveness in the short term, and a promise to sustain nature and people in the long term.
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