Digital library

  • Aquatic Polyculture and Balanced Ecosystem Management: New Paradigms for Seafood Production

    Chinese aquaculture has employed a balanced ecosystem approach for freshwater aquaculture for several thousand years. Utilizing species that feed at different levels of the food web has permitted China to have the largest freshwater aquaculture production in the world. This production has proved to be sustainable in the long run because there is balance in this system. This concept is just starting to be thought of for broader aquaculture, including marine operations at sea or on land, and fishery communities around the world.

    The National Oceanic and Atmospheric Administration has developed a Sustainable Fisheries Implementation Plan that recognizes three key elements - fisheries, aquaculture and coastal communities - for obtaining sustained production of seafood in the United States. The concepts of carrying capacity for biological activities in  a hydrographic system; ecological balance between primary producers, primary and secondary consumers; and nutrient flows in ecosystems are essential elements for the future development of world aquaculture and fisheries.

    This chapter documents the present status of selected polyculture systems being employed by the aquaculture industry, provides examples of balanced ecosystem approaches to aquaculture and fisheries, and examines the question of how to develop models for maximizing the production of seafood through fisheries and aquaculture working in harmony to minimize environmental impacts.

    Author(s): James P. McVey, Robert R. Stickney, Charles Yarish, Thierry Chopin

  • Artificial seed production and cultivation of Sargassum macrocarpum (Fucales, Phaeophyta)

    Sargassum macrocarpum is a rich source of anti-inflammatory compounds. Recently, one of the compounds, tuberatolide B, has been reported as a functional anti-inflammatory additive for foods and nutraceuticals. The artificial seeding, growth and maturation of S. macrocarpum were investigated from May 2018 to September 2019. Indoor culture experiments for induction of egg release were conducted at temperatures of 17, 20, 23, and 26°C and irradiances of 0, 10, 20, 40, and 80 μmol photons m-2 s-1 under 14 : 10 h (L : D) photoperiod. Within a given treatment combination, higher temperatures and irradiance levels favoured the maturation of receptacles in S. macrocarpum. Using artificial temperature and irradiance control, thalli matured one month earlier than thalli in nature. Under natural condition, receptacle formation began in April, and the eggs were released in June and July. The release of eggs from the receptacles was promoted at 17-20°C and 40-80 μmol photons m-2 s-1, and the fastest growth of germlings occuring at 15-17°C and 40 μmol photons m-2 s-1. For mature thalli, 300 g wet-weight was sufficient to seed 100 m of seed string. Thalli grew to 10.5 ± 2.6 cm in length at a density of 6.7 ± 3.3 individuals m-1 after 1 year of cultivation, from germination. This study demonstrates that it is possible to cultivate S. macrocarpum for the production of anti-inflammatory products.

    Author(s): Shin Ja Ko, Yoo Kyung Kim, Seong Wan Hong, Min Su Kang , Chan Sun Park, Eun Kyoung Hwang, Young Don Lee

  • Astaxanthin in microalgae: pathways, functions and biotechnological implications

    Major progress has been made in the past decade towards understanding of the biosynthesis of red carotenoid astaxanthin and its roles in stress response while exploiting microalgae-based astaxanthin as a potent antioxidant for human health and as a coloring agent for aquaculture applications. In this review, astaxanthin-producing green microalgae are briefly summarized with Haematococcus pluvialis and Chlorella zofingiensis recognized to be the most popular astaxanthin-producers. Two distinct pathways for astaxanthin synthesis along with associated cellular, physiological, and biochemical changes are elucidated using H. pluvialis and C. zofingiensis as the model systems. Interactions between astaxanthin biosynthesis and photosynthesis, fatty acid biosynthesis and enzymatic defense systems are described in the context of multiple lines of defense mechanisms working in concert against photooxidative stress. Major pros and cons of mass cultivation of H. pluvialis and C. zofingiensis in phototrophic, heterotrophic, and mixotrophic culture modes are analyzed. Recent progress in genetic engineering of plants and microalgae for astaxanthin production is presented. Future advancement in microalgal astaxanthin research will depend largely on genome sequencing of H. pluvialis and C. zofingiensis and genetic toolbox development. Continuous effort along the heterotrophic-phototrophic culture mode could lead to major expansion of the microalgal astaxanthin industry.

    Author(s): Danxiang Han , Yantao Li, Qiang Hu

  • Back to the future — with seaweed

    A story ran in the August 4, 1972 issue of the Portland Press Herald with the headline: “A Future for Seaweed?” The answer is yes. The story was about a young entrepreneur,Robert Morse, who started a seaweed processing

    business, the Samoset Algae Co., in 1971.

    Author(s):

  • Bio-products from algae-based biorefinery on wastewater: A review

    Increasing resource demand, predicted fossil resources shortage in the near future, and environmental concerns due to the production of greenhouse gas carbon dioxide have motivated the search for alternative ‘circular’ pathways. Among many options, microalgae have been recently ‘revised’ as one of the most promising due to their high growth rate (with low land use and without competing with food crops), high tolerance to nutrients and salts stresses and their variability in biochemical composition, in so allowing the supply of a plethora of possible bio-based products such as animal feeds, chemicals and biofuels. The recent raising popularity of Cir- cular Bio-Economy (CBE) further prompted investment in microalgae, especially in combination with wastewater treatment, under the twofold aim of allowing the production of a wide range of bio-based products while bio- remediating wastewater. With the aim of discussing the potential bio-products that may be gained from microalgae grown on urban wastewater, this paper presents an overview on microalgae production with particular emphasis on the main microalgae species suitable for growth on wastewater and the obtainable bio- based products from them. By selecting and reviewing 76 articles published in Scopus between 1992 and 2020, a number of interesting aspects, including the selection of algal species suitable for growing on urban wastewater, wastewater pretreatment and algal-bacterial cooperation, were carefully reviewed and discussed in this work. In this review, particular emphasis is placed on understanding of the main mechanisms driving formation of microalgal products (such as biofuels, biogas, etc.) and how they are affected by different environmental factors in selected species. Lastly, the quantitative information gathered from the articles were used to estimate the potential benefits gained from microalgae grown on urban wastewater in Campania Region, a region sometimes criticized for poor wastewater management. 

    Author(s): C.M. Catone , M. Ripa, E. Geremia, S. Ulgiati

  • Bio-prospecting of macro-algae for potential industrial dyes

    Synthetic dyes have been used for different purposes in various fields, but their continued usage has presented both environmental and health challenges. Therefore, alternative safer dye sources are inevitable. Algae have different pigments with potential for exploitation and usage in different socio- economic sectors. The aim of this study was to bio prospect dyes from macro-algal species of the Indian Ocean marine ecosystem. Six algal samples were collected from Coastal beaches along the Kenyan Indian Ocean during the wet and dry seasons. The samples were processed and used for pigment extraction and screening. Pigments were extracted using ethanol, acetone, diethyl ether and hexane in sequential with distilled water. Subsequently, the crude extracts were analyzed for pigment component using spectrophotometry and qualitatively for presence of active components. From the six species, Ulva reticulata was the best dye producer in ethanol and distilled water. All extracts were coloured green except those from Galaxaura subverticillata which gave a dark red extract in 80% hexane and a brown extract in distilled water. The crude extracts also contained different active components, with phenols being the most common component in ethanol and acetone extracts. This study demonstrates that macro-algae species from the Indian Ocean ecosystem contain useful pigments for biotechnological exploitation. Future studies should focus on increasing the pigment content through genetic manipulation of macroalgae and analysis of the pigments using modern methods such as the gas chromatography-mass spectrometry (GC-MS). 

    Author(s): Christine W. Njiru , Huxley M. Makonde, John M. Kahindo, Edwin O. Matoka, Charles M. Matoka

  • Bioactive compounds in seaweed: functional food applications and legislation

    Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value- added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews world- wide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value- added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed. 

    Author(s): Susan Løvstad Holdt, Stefan Kraan

  • Biochemistry of methanogenesis

    The recent and unexpected finding that methanogenic bacteria occupy an isolated biochemical island in the sea of procaryotes has added a touch of excitement to the study of these organisms1. This island is defined by such diverse biochemical qualities as: a very restricted range of oxidizable substrates coupled to the biosynthesis of methane; synthesis of an unusual range of cell-wall components; synthesis of biphytanyl glycerol ethers as well as high amounts of squalene; synthesis of unusual coenzymes and growth factors; synthesis of rRNA that is distantly related to that of typical bacteria; possession of a genome size (DNA) approaching 1/3 that of E. coli.

    Author(s): R. S. Wolfe

  • Bioconversion of algae to methane and subsequent utilization of digestate for algae cultivation: A closed loop bioenergy generation process

    The present investigation was targeted on anaerobic digestion of Chroococcus sp. and utilization of resul- tant ‘‘Liquid Digestate’’ for its further biomass production. The algal biomass has biomethane potential of 317.31 ± 1.9 mL CH4 g1 VSfed. Regular process monitoring revealed that process was stable throughout the experiments. The ‘‘Liquid Digestate’’ was explored as nutrient supplement for further algal growth. Diluted ‘‘Liquid Digestate’’ (30% concentration) was found optimal for algal growth (0.79 ± 0.064 g L1). Simultaneously, 69.99–89.31% removal in nutrient and sCOD was also recorded with algal growth. Inter- estingly, higher growth was observed when rural sector wastewater (1.29 ± 0.067 g L1) and BG11 broth (1.42 ± 0.102 g L1) was used for diluting the ‘‘Liquid Digestate’’. The current findings have practically proven the feasibility of hypothesized ‘‘closed loop process’’. 

    Author(s): Sanjeev Kumar Prajapati, Pushpendar Kumar, Anushree Malik, Virendra Kumar Vijay

  • Biodiversity, Biogeography and Molecular Genetics of the Commercially Important Genera Kappaphycus and Eucheuma

    Through the years, several strains and color morphotypes of Kappaphycus and Eucheuma have emerged in cultivation areas as a result of environmental and anthropogenic factors. This led to confusion in nomenclature of these seaweeds. However, the advent of molecular technology has brought notable changes to seaweed research over the past two decades. New molecular techniques have proved useful, particularly in the molecular identification and cataloging of economically important carrageenophytes, i.e. Kappaphycus and

    Eucheuma which were commercially introduced into many countries worldwide. The following chapter discusses the application and findings of molecular studies within the context of these red seaweeds, along with potential areas for future research.

    Author(s): Ji Tan, Phaik-Eem Lim, Siew-Moi Phang, Anicia Q. Hurtado

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