Marine botanical research activities in the Western Indian Ocean region have increased significantly over the past two decades, contributing to a growing awareness and enhanced understanding of the important values and functions of the main primary producers in the coastal ecosystems of this region (UNEP 1982). Whereas a major proportion of the research has been descriptive, focusing on the distribution and general biology of mangrove, seaweed and seagrass plants and microalgae, more recent research has diversified its attention to include various other more quantitative and applied research topics (Björk et al. 1996). Throughout the region, increasing efforts are underway for coastal zone management, mangrove rehabilitation and marine conservation (e.g. Tanzania Coastal Management Partnership 1999), which call for a solid scientific knowledge base. Yet, new research initiated without a thorough review of past and recent research outputs may lead to a deficiency in the relevance of the knowledge being produced (Hatcher et al. 1989). The present review of the current status of marine botanical research (1950–2000) in the Eastern African region was made to provide a diagnosis of its strengths and weaknesses, with the aim of identifying the main research challenges to be faced to assist in the development of a solid basis for the management, conservation and wise use of the marine botanical resources in this region.
Digital library
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Objective of Talk
Discuss the challenges with the selection of materials of construction, design of equipment, and assessment of equipment/material reliability for a continuous and commercially operating HTL (Hydrothermal Liquefaction) process in Saltwater environments
Agenda
1. Brief review of process operating conditions in HTL of Algal Biomass
2. Factors Affecting Materials Selection and Equipment Design
3. Considerations in Selection of Materials of Construction
4. Corrosion Mechanisms of Candidate Alloys
5. Factors Affecting Equipment Design
6. Conclusion and Recommendations
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Petroleum-based plastics are mass produced to meet customers’ demand due to their low cost and versatility. However, plastic waste has become a serious environmental problem. Hence, degradable plastics from renewable sources (e.g. biomass) are now trending for their “green” properties. In this paper, properties of biofilms made from whole seaweed (WS), Kappaphycus sp. and pure kappa-carrageenan powder (PC) were compared. Glycerol, as plasticizer, was added at differing amounts (1%, 2%, 3%, 4% and 5%, v/v) and their appearance, physical and mechanical properties, solubility, and biodegradability were studied. As results, for colour difference and transparency, WS- 1% showed higher ΔE at 17.09 ± 0.85 with highest opacity at 13.73 mm-1 and least ΔE was at 2.73 ± 0.13 for PC-5% with opacity at 0.49 mm-1. For mechanical properties, PC- 1% has the highest tensile strength and elastic modulus at 26.63 ± 2.18 MPa and 253.53 ± 19.43 MPa, respectively, whereas WS-5% has the lowest at 0.71 ± 0.15 MPa and 2.47 ± 0.44 MPa, respectively. As for biodegradability, by the first week, WS-5% lost 80% of its weight and PC-1% only lost 3%. Overall, PC biofilms showed better quality in terms of mechanical and physical properties but WS biofilms were faster to degrade and dissolve in water. Glycerol concentration affects most of the properties except for mechanical properties for WS and solubility of both. This study suggests that PC may be a better base material for stronger biofilms but WS are a better choice from environmental and cost aspects.
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Gracilaria tikvahiae, an endemic western North Atlantic red alga, was cultivated for nutrient bioextraction in urbanized estuarine waters in Long Island Sound and the Bronx River Estuary, USA. This study assesses the feasibility of an integrated approach of using G. tikvahiae produced in this bioextraction system as sustainable biomass source for agar production. Agars were extracted after alkaline pre-treatment and characterized in terms of gelling strength, chemical composition, chemical structure and gel structure. Results indicated that this seaweed performed similar to other cultivated Gracilaria in terms of extraction yield and gelling strength of the agar. Differences between sites were not significant in terms of agar gel strength, though yield was higher at Long Island Sound. The extracted agars were sulfated, methylated and with no detectable pyruvate substituents. It is possible to use an integrated strategy of nutrient bioextraction in urbanized estuarine waters and agar exploitation with G. tikvahiae.
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Considerable work has been done on the chemical aspects of Indian seaweeds during the last three decades, of which those up to 1970 have been reviewed by Umamaheswara Rao (1970). In this chapter the information so far collected on the mineral constituents, carbohydrates and other chemicals is presented.
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There is strong evidence for the importance of naturally produced compounds as mediators of ecological interactions between marine benthic consumers and their prey, e.g., in plant-herbivore and predator-prey interactions (reviewed by Hay, Hay and Steinberg, McClintock and Baker, Paul, and Pawlik). Dozens of characterized, ecologically relevant feeding deterrents are known from marine benthic organisms (reviewed by Hay and Paul). As a consequence, studies of chemically mediated plant-herbivore or predator-prey interactions have increasingly moved beyond a consideration of simple feeding deterrence to address more complex ecological and evolutionary issues such as induction of defenses, specialization of consumers, and geographic variation in defenses.
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There is practically no reference which gives a complete account of the mineral constituents of the commercial seaweeds and their relationship with the organic constituents or on the- ionic exchanges taking place between the algae and the surrounding water. The early attempts to utilize seaweeds for the manufacture of potash and iodine provide some data on the amounts of these elements and their seasonal variations in particular species. Work on British seaweeds has shown (Chapman, 1950) that the changes in the iodine content are nearly directly proportional to the potash and that the amount of these nutrients in the living plant varies from month to month.
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Several interesting studies have been made in the past on the nitrogen metabolism in seaweeds. Haas and Hi11 (1931) and Haas, Hill and Karstens (1935) isolated water-soluble peptides from the brown alga Pelvetia canaliculata and explained their presence as due to lack of metabolic balance traceable to either desiccation or low illumination. To obtain further evidence Haas, Hill and Russel-Wells (1938) examined the calcareous algae Corallina squamata Ellis, Lithophylum incrustans Foslie, Amphiora capensis Aresch and Galaxaura subverticillata Kjell. A number of unencrusted algae were also examined, but so far among the latter group peptides were found only in the two species, Pelvetia canaliculata and Griffithsia flocculoses. It was found that the encrusted forms contained crude peptides to the extent of 0.05 to 0.29% of the dry weight.
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Seaweeds in general derive their importance from their carbohydrate content. Part of the carbohydrate is in the form of cellulose which cannot be hydrolysed by ordinary means; and the rest in the form of polysaccharides either as agar or as algin, the latter being considered as a polymerised form of d-mannuronic acid. Kylin (1913) is of the opinion that simple reducing sugars constitute the first products of photosynthesis and that they occur in very small quantities.
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PDF on final report of 'Preliminary Study - Chinese Market for Seaweed and Carrageenan Industry'.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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