Digital library

  • IMTA with Gracilaria vermiculophylla: Productivity and nutrient removal performance of the seaweed in a land-based pilot scale system

    The use of ecological engineering tools for the development of a more sustainable aquaculture is crucial. In this context, seaweed based Integrated Multi-Trophic Aquaculture (IMTA) systems are being designed to mitigate the environmental problems caused by several forms of fed aquaculture. Several macroalgal species, namely some from the genus Gracilaria, have been shown to be efficient biofilters,. Gracilaria vermiculophylla thrives in Ria de Aveiro lagoon, Portugal (40°38N, 8°43°W). It has been an unexploited resource for the production of agar. A seaweed cultivation system with 1200 L tanks was installed at a sole and turbot land-based aquaculture facility to evaluate the potential of this species as the biofilter component of an IMTA system. A year round, full factorial experiment was done, testing for the influence of stocking density (3, 5 and 7 kg m− 2 (fw)), water exchange rate (100 and 200 L h− 1) and time of the year on G. vermiculophylla's relative growth rates (RGR), productivity and nutrient removal.

    G. vermiculophylla was able to maintain a good overall performance; however, results indicate that the culture conditions require adaptations throughout the year in order to attain successful productivities. In general, biomass production and nutrient removal were negatively related to the cultivation densities in the system. In the tanks seeded with 3 kg fw m− 2, the production of G. vermiculophylla was 0.7 ± 0.05 kg dw m− 2 month− 1; this biomass removed 221 ± 12.82 g m− 2 month− 1 of carbon and 40.54 ± 2.02 g m− 2 month− 1 of nitrogen (± 0.03% of the monthly fish N inputs). Temperature and light were the main environmental factors conditioning the growth and nutrient removal performance of the seaweed. With the appropriate upscaling, this pilot IMTA system is ready for implementation at fish aquaculture operations. G. vermiculophylla has proved to be an efficient component of land-based IMTA systems with environmental and potentially economic benefits for the fish farm.

    Author(s): Yarish, Charles Isabel Sousa-Pinto, Alejandro H. Buschmann, Rui Pereira, Maria H. Abreu

  • Incredible uses for seaweed from the sea to everywhere

    This presentation covers

    • What seaweeds are
    • The history of seaweed cultivation
    • The use of seaweed in food, merchandise, medicine, biofuel, fertilizers, animal feed, and etc.
    Author(s):

  • Influence of physicochemical parameters on the removal of nitrogenous compounds during treatment of fish effluent with seaweeds

    Fish effluent was treated with Gracilaria corticata and Ulva lactuca in separate tanks. Effluent without seaweeds was kept as control. Physicochemical parameters such as pH, Biological Oxygen Demand, Dissolved Oxygen on nitrogenous compounds such as ammonia, nitrite and nitrate were monitored. The DO content was found to be 15 % more in the treatment tanks of G.corticata (5.44 ml/l) when compared to the control (4.05 ml/l) during same period, may account for the high photosynthetic activity and efficient utilization of dissolved carbon in the effluent. The BOD value was observed to be more in the treated tank of G.corticata compared to control on 20 days of treatment, could be due to the growth of associated bacteria in the system, which favoured the oxidation of ammonia to nitrite and then to nitrate. The pH was found to have significant positive correlation with nitrate content in all the treatments, whereas BOD exhibited a negative correlation with nitrate. The removal of nitrogenous compounds was found to be more in the effluent treated with U. lactuca followed by G. corticata than the control.

    Author(s): Seema, C, Jayasankar, Reeta, Mathew, Grace

  • Innovations in Sustainable Agriculture: Supporting Climate-Friendly Food Production

    Fifteen or twenty years ago, it was easy for pastoralists in Samburu, Kenya, to find water for their Zebu cattle, a livestock breed that has adapted over centuries to the region’s hot temperatures and arid landscape. But today things have changed. Water is increasingly scarce, and in 2010 and 2011 severe drought across eastern Africa killed thousands of animals, including 60 percent of herds in parts of Kenya and Ethiopia. The drought also fueled or intensified conflicts over grazing and water rights between many of the region’s communities.

    In Russia, meanwhile, wheat farmers experienced the worst drought in over a century in 2010: one-quarter of the country’s wheat crop was lost, and forest fires raged across more than a million hectares. At the height of the drought, Russia’s then-President Dmitri Medvedev, who previously had voiced skepticism about climate change, urged, “What’s happening with the planet’s climate right now needs to be a wake-up call to all of us.”

    Author(s): Laura Reynolds, Danielle Nierenberg

  • Innovative Ultrasound-Assisted Approaches towards Reduction of Heavy Metals and Iodine in Macroalgal Biomass

    The aim of this work was to evaluate the potential of ultrasound (US), alone or in combination with mild heating and/or EDTA towards reduction of As, Cd, I, and Hg content of Laminaria hyperborea. Concentrations of As, Cd, I, and Hg of 56.29, 0.596, 7340, and <0.01 mg kg−1 of dry weight, respectively, were found in L. hyperborea blades. Treatment with US at 50 ◦C increased approx. 2-fold the amount of As released, although did not affect significantly the content of Cd or I, as compared to control (no US) samples. Reducing the temperature to 8 ◦C significantly decreased the effect of US, but heating at 80 ◦C did not cause a significant effect as compared to treatments at 50 ◦C. On the other hand, treatment with 0.1 N EDTA at 50 ◦C enhanced the percentage of Cd released by approximately 7-fold, regardless of sonication. In the present work, the combination of US and EDTA at 50 ◦C for 5 min led to a significant reduction of the As (32%), Cd (52%) and I (31%) content in L. hyperborea, thus improving the product’s safety for consumers.

    Author(s): Guillermo Cebrián, Ignacio Álvarez, Morten Sivertsvik, Leena Prabhu, Leire Astráin-Redín, Izumi Sone, Estefanía Noriega-Fernández

  • 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

  • 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

  • Integration of Fed and Extractive Aquaculture

    Integration of the fed and extractive components in an approach to aquaculture that seeks balance to protection of the environment and increasing total production. Our human tendency is focus only on high value and high production aquaculture. When an innovative aquaculture succeeds everyone adopts that system and concentrates aquaculture in areas were it was successfully. Aquaculturalists then strive to increase production by intensifying the system. This usually evolves into high-density monoculture systems. Such an approach to aquaculture leads to deterioration of environmental quality. Disease outbreaks made more virulent by the high density of organisms and by stressful environmental conditions. In pond aquaculture, the aquaculturist monitors and is responsible for balancing production with environmenal conditions. When aquaculture moves to the public waters, such as Jiaozhou Bay or Xincun Bay, the aquaculturist does not control the situation and the primary responsibility of maintaining a balance between the environment quality and aquaculture production usually shifts toa government resource management agency. In bays aquaculture is rarely the only user of the resources, and management agencies are faced with competing demands. Integrating the resource uses is not an easy task. Managers must use an approach of integrated coastal management (ICM) and must have the scientific tools to understand the impacts of various resource uses. The 3-dimensional models offer such a tool for integrating the impacts of human activity and natural environmental processes on an embayment. 

    Author(s): Yarish, Charles R. Carmona, Thierry Chopin, James B Sullivan, L. Wang, Wang Daoru, M. Zhu, Rubao Ji, C. Chen, M.V. Rawson

  • Investigation of the effect of K. alvarezii on antioxidant enzymes, cell viability and DNA damage in male rats

    In recent years, a significant number of novel metabolites with potent pharmacological properties (antioxidant, antitumor, anti-HIV) have been discovered from marine organisms. Kappaphycus alvarezii (Doty) is a marine alga belonging to order: Gigartinales and family: Solieriaceae. It has been invasive in the Gulf of Mannar since 2000, and has a high content of the steroid phenol. This is the first report on its antioxidant properties using an animal model. This study aimed to explore the antioxidant and antigenotoxic/protective role of K. alvarezii growing in southeast coast of India in the male rat. The findings indicate that an extract of K. alvarezii is not nephrotoxic at the dose levels. The algal antioxidant activity shows similar correlation (89%; R2 = 0.8963) at varying temperature to the known antioxidant. K. alvarezii extracts exhibit significant protective effects against DNA damage induced by H2O2, which might be related to antioxidant activity. In conclusion, our results suggest that long-term daily administration of K. alvarezii extract offers enhanced antioxidant potential and protection against tissue lipid peroxidation and cell damage. Our results support the use of K. alvarezii in the food and pharmaceutical industries.

    Author(s): A. K. Kumaraguru, N. Nagarani

  • Is there a need for seaweed in human nutrition?

    In the Far East and Pacific Islands, there has been a long tradition of consuming seaweed as sea vegetables, while in Western countries the main use of seaweed has been as source of phycocolloids (alginate, carrageenan and agar) used as thickening and gelling agents in various industrial applications, including food processing. Seaweed is also a source of compounds with protective health effects. The beneficial effects of seaweed on human health appear to derive from the presence of three categories of constituents (fibre, proteins and minerals) as well as metabolites with antioxidant properties, including carotenoids, polyphenols, vitamins and polyunsaturated fatty acids.

    Author(s): H. Marfaing, Y. Lerat

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