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  • Integration of seaweed (Kappaphycus alvarezii) and pearl oyster (Pinctada fucata) along with Asian seabass (Lates calcarifer) in open sea floating cage off Andhra Pradesh coast

    Aquaculture is growing very fast and its growth is expected to continue and it is necessary to supply fish for the ever growing population of our country. In India, fish production and consumption is considered to be important and needs to be promoted. As capture fisheries have almost become stagnant, diversification of aquaculture is highly necessary.

    Considering the limited scope of freshwater aquaculture and the availability of vast coastline, open sea cage culture gained importance in the present day mariculture practice. Open sea floating cage culture is an alternative sustainable practice for rearing fish and shellfish species and polyculture along with seaweeds may also improve profitability and sustainability. Open sea cage culture is an aquaculture production system where high density of fish is cultured in floating cages. Floating cages are widely used in commercial aquaculture and individual cage units of desired shapes and sizes can be tailored to suit the needs.

     

    Author(s):

  • Integrated Multi-Trophic Aquaculture Part II. Increasing IMTA Adoption

    Integrated multi-trophic aquaculture involves cultivating fed species with extractive species that utilize wastes from aquaculture for their growth. All components  have commercial value, as well as roles in biomitigating. The IMTA concept  should also be understood within an integrated land/coastal aquaculture ecosystem  approach. Regulatory frameworks and financial incentives may be required  to fully realize the benefits of IMTA systems. Differentiation of IMTA products through traceability and ecolabeling will be key in their promotion.

    Author(s): Thierry Chopin, Max Troell, Gregor K. Reid, Duncan Knowler, Shawn M. C. Robinson, Amir Neori, Alejandro H. Buschmann, Shaojun Pang

  • Integrated Multi-Trophic Aquaculture Part I. Responsible Practice Provides Diversified Products, Biomitigation

    Integrated multi-trophic aquaculture involves cultivating fed species with extractive species that  utilize the inorganic and organic wastes from aquaculture for their growth. The mix of organisms of different trophic levels mimics the functioning of natural ecosystems. All the cultivation components have commercial value, as well as key roles in recycling processes and biomitigating services. Some of the externalities of fed monoculture are internalized, increasing the overall sustainability and long-term profitability of aquaculture farms.

    Author(s): Thierry Chopin, Max Troell, Gregor K. Reid, Duncan Knowler, Shawn M. C. Robinson, Amir Neori, Alejandro H. Buschmann, Shaojun Pang

  • Information to Support Assessment of Stock Status of Commercially Harvested Species of Marine Plants in Nova Scotia: Irish Moss, Rockweed and Kelp

    A literature review was performed which included examining over 200 publications relevant to

    the harvest of marine plants in Nova Scotia. The seaweeds included Irish moss (Chondrus

    crispus), rockweed (Ascophyllum nodosum) and kelps. The history of each harvest is presented

    along with an analysis of the harvest methods, timing and intensity of the harvests, and standing

    stocks. Environmental effects on the standing stocks were also examined. One of the guiding

     

    principles of the assessment was the preservation of the habitat value of the seaweeds on bay-

    wide scales in the face of harvest pressure.

    Author(s): H. Vandermeulen

  • Influence of different wavelengths of light on photosynthesis and pigment constituents and absorption spectra of Gracilaria spp.

    Three species of Graci/aria such as G.edulis, G. crassa and G. corticata were exposed to different broad band of lights. Red (> 600 nm), green (450-610 nm) and blue (390·570 nm) lights were provided to the plants kept in different growth chambers maintained with constant temperature of 28°C and photoperiod of 16:8 h light and dark period. The plants maintained under WL were considered as controL Photosynthetic activity and chlorophyll content were found to increase in all the species during 6th day of observation. Plants maintained GL exhibit higher cOIwentration of chlorophyll in G.edulis and G. corticata.

    Author(s): Jayasankar, Reeta , Kulandaivelu, G

  • In vivo fluorescence kinetics of Gracilaria spp. subjected to different salinities

    Gracilaria species were subjected to different salinities under laboratory conditions and changes in the photosynthetic oxygen evolution and fluorescence kinetics were followed. The plants which were subjected to more or less the normal salinity conditions exhibited low values of variable fluorescence and quantum yield. Prolonged treatment increased the quantum yield but the pigment content and the photosynthetic rate reduced significantly Among the two species tested, Gracilaria edulis was found to be very sensitive to low salinity (15 ppt) and G. crassa to higher salinity (45 ppt).

    Author(s): Jayasankar, Reeta , Kulandaivelu, G

  • Improvement of yield and quality of agar from Gracilaria edulis (Gmelin) Silva

    Optimum levels of alkali/acid and thermal manipulations during extraction of agar were determined to increase the yield and quality of agar from red seaweed Gracilaria edulis (Gmelin) Silva. Pre-soaking of dry weeds in water for 2 h increased the yield by 11.44%, but did not improve the gel strength. Pre-soaking for 12 h increased gel strength and melting temperature considerably, but not the yield. Pre-soaking of dry weeds in 1.ON NaOH resulted in gel strength of 135 g.cm -2. Pre-soaking of dried weeds with 0.5N and 1.ON HCl even at higher temperature showed improvement neither in yield nor in the quality of agar and also resulted in hydrolysis of agar. Pretreatment at 2.0 - 3.0 N NaOH at 80°C for 1 hour to pre-soaked G.edulis for 11 h in water proved to be the most ideal and optimum extraction procedure to obtain higher yield (14.16%), maximum gel strength (291g.cm -2 ), lowest sulphate (0.732%) and highest melting point (99°C) of agar.

    Author(s): Rao, A Chandrasekhara, Kaladharan, P

  • IMPACT OF SEAWEEDS IN AGRICULTURE

    Seaweeds contain a considerable amount of micronutrients and plant growth hormones like auxins, gibberellins, cytokinins, and betaines etc. which are supposed to help plant growth and also in seed germination. The extracts of seaweeds have proved itself as a highly effective and eco- friendly pesticide against various crop pests. This chapter provides an overview of the varieties of seaweeds, their ecology and their utilization worldwide. The main concept of this chapter delves into the possible utilization of selected seaweeds in agriculture. The various forms of seaweeds such as seaweed extract (SWE), compost, mulch etc. and their applications as bio-stimulators, growth promoters, crop protection, soil conditioner, and stabilizer are discussed.

    Author(s): Yuvaraj Dinakarkumar, Gayathri Kothandaraman

  • Hydrothermal carbonization of microalgae II. Fatty acid, char, and algal nutrient products

    A process for isolation of three products (fatty acids, chars and nutrient-rich aqueous phases) from the hydrothermal carbonization of microalgae is described. Fatty acid products derived from hydrolysis of fatty acid ester groups in the microalgae were obtained in high yield and were found to be principally adsorbed onto the char also created in the process. With the highest lipid-containing microalga investigated, 92% of the fatty acids isolated were obtained by solvent extraction of the char product, with the remaining 8% obtained by extraction of the acidified filtrate. Obtaining the fatty acids principally by a solid–liquid extraction eliminates potential emulsification and phase separation problems commonly encountered in liquid–liquid extractions. The aqueous phase was investigated as a nutrient amendment to algal growth media, and a 20-fold dilution of the concentrate supported algal growth to a level of about half that of the optimal nutrient growth medium. Uses for the extracted char other than as a solid fuel are also discussed. Results of these studies indicate that fatty acids derived from hydrothermal carbonization of microalgae hold great promise for the production of liquid biofuels.

    Author(s): Kenneth J. Valentas, Marc G. von Keitz, Paul A. Lefebvre, Frederick J. Schendel, Michael J. Sadowsky, Laurie A. Harned, Lindsey R. Jader , Steven M. Heilmann

  • Hydrothermal carbonization of microalgae

    Hydrothermal carbonization is a process in which biomass is heated in water under pressure to create a char product. With higher plants, the chemistry of the process derives primarily from lignin, cellulose and hemicellulose components. In contrast, green and blue-green microalgae are not lignocellulosic in composition, and the chemistry is entirely different, involving proteins, lipids and carbohydrates (generally not cellulose). Employing relatively moderate conditions of temperature (ca. 200 C), time (<1 h) and pressure (<2 MPa), microalgae can be converted in an energy efficient manner into an algal char product that is of bituminous coal quality. Potential uses for the product include creation of synthesis gas and conversion into industrial chemicals and gasoline; application as a soil nutrient amendment; and as a carbon neutral supplement to natural coal for generation of electrical power.

    Author(s): Kenneth J. Valentas, Marc G. von Keitz, Frederick J. Schendel, Michael J. Sadowsky, Paul A. Lefebvre, Lindsey R. Jader, Steven M. Heilmann, H. Ted Davis

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