Digital library

  • Understanding the recurrent large-scale green tide in the Yellow Sea: Temporal and spatial correlations between multiple geographical, aquacultural and biological factors

    The coast of Jiangsu Province in China e where Ulva prolifera has always been firstly spotted before developing into green tides e is uniquely characterized by a huge intertidal radial mudflat. Results showed that: (1) propagules of U. prolifera have been consistently present in seawater and sediments of this mudflat and varied with locations and seasons; (2) over 50,000 tons of fermented chicken manure have been applied annually from March to May in coastal animal aquaculture ponds and thereafter the waste water has been discharged into the radial mudflat intensifying eutrophication; and (3) freefloating U. prolifera could be stranded in any floating infrastructures in coastal waters including large scale Porphyra farming rafts. For a truly integrated management of the coastal zone, reduction in nutrient inputs, and control of the effluents of the coastal pond systems, are needed to control eutrophication and prevent green tides in the future.

     

    Author(s): Feng Liu, Shaojun Pang, Thierry Chopin, Suqin Gao, Tifeng Shan, Xiaobo Zhao, Jing Li

  • Understanding the Interaction of Extractive and Fed Aquaculture Using Ecosystem Modelling

    One of the most difficult tasks resource managers face is understanding the carrying capacity of coastal waters for aquaculture. Aquaculture, like many other human activities, can threathen coastal waters. Understanding eutrophication and the interaction of two diffierent types of aquaculture is very important to the safe and effective management of coastal aquaculture. The first type of aquaculture, producing shrimp and finfish depends on supplemental feeding and can contribute to eutrophication. The second type, involving bivalve molluscs and macroalgae, extracts plankton and nutrients from surrounding waters and can have a significant positive impact on moderately eutophic waters. These species depend on the water's basic productivity and will not grow effectively in water with low nutrient levels. Balancing extractive and fed aquaculture is of obvious importance to maximizing the safety and optimizing the carrying capacity of an embayment.

    Ecosystem modelling offers a three-dimensional physical, chemical and biological simulation that can help scientist and managers understand and predict the eutrophic impact of aquaculture for a specific embayment. Such a model is being explored in China in research sponsored by the Sino-US Living Marine Resources Panel. In this study, two projects are using the model to simulate the impact of aquaculture on Jiaozhou Bay, Shangdong Province, and on Xincun Lagoon, Hainan Province. Jiaozhou Bay is in the temperate zone adjacent to the Yellow Sea.

    There, a major port and industrial city, Qingdao, and scallop and shrimp aquaculture interact with the physical and biological components of the bay. The other modelled environment is very different. Xincun Lagoon is a small embayment (~22 km^2) in southeastern Hainan Island adjacent to the South China Sea. Aquaculture in Xincun Bay includes 6500 fish pens ( 3m X 3 m), 100 ha of shrimp ponds, pearl culture rafts and a new macroalgae culture operation that produced 3500 tonnes of Eucheuma in 1998-1999. The surrounding area has ~15,000 people and Xincun City is a major offshore fishing port (~500 vessels, > 10 m length) and Monkey Island Wildlife area with > 400,000 visitors annually. Extractive and fed aquaculture, along with the external activities, all have an impact on the carrying capacity of the bay for aquaculture.

    These two models show much promise for simulating local eutrophic conditions and for increasing the general understanding  of the complex interactions of aquaculture and other human activities and eventually predict carrying capacity should become useful tools for resource managers.

    Author(s): Mac V. Rawson, Jr, Changsheng Chen, Rubao Ji, Mingyuan Zhu, Daoru Wang, Lu Wang, Charles Yarish, James B. Sullivan , Thierry Chopin, Raquel Carmona

  • Understanding biosecurity: knowledge, attitudes and practices of seaweed farmers in the Philippines

    Farmers are one of the most important components of any plant-based cultivation industry. The Philippines is one of the world’s major producers of red carrageenophyte algae and has tens of thousands of farmers involved in this industry. The production of algae such as Kappaphycus and Eucheuma increased significantly from the early 1970s, when the industry was established, before declining from the mid-2000s, due to a number of reasons, including disease and epiphyte outbreaks. The introduction of biosecurity measures has been one approach used to tackle this decline. Biosecurity-related knowledge, attitude and practices (KAP) of the seaweed farmers were assessed in the four highest seaweed producing regions in the Philippines: (1) Tawi-Tawi, (2) Palawan, (3) Zamboanga and (4) Bohol. Analyses showed that seaweed farmers from Tawi-Tawi had relatively higher KAP mean scores than the other three sites. Palawan and Bohol farmers, however, scored lower on their knowledge, higher on their attitude and highest on their practices compared with the other areas. Farmers from Zamboanga scored the lowest in both their attitude and practice mean scores, although their knowledge score was one of the highest. This is the first KAP assessment applied to the seaweed farming industry globally and the results, in which the farmers’ biosecurity-related knowledge and practices, which scored “Fair” (50–75%) across all the regions, and their attitudes, which scored predominantly “Good” (> 75%) suggest that there is potential to raise the score for biosecurity practices. This assessment highlights how biosecurity challenges are currently addressed by seaweed farmers in the Philippines and suggests how the KAP survey could be used as a tool by policymakers and scientists to address gaps in biosecurity management practices.

    Author(s): Jonalyn P. Mateo, Iona Campbell, Elizabeth J. Cottier-Cook, Maria Rovilla J. Luhan, Victor Marco Emmanuel N. Ferriols, Anicia Q. Hurtado

  • Undaria pinnatifida (Harvey) Suringar, 187)

    FAO fisheries fact sheet on Undaria pinnatifida (Harvey) Suringar, 187), also called wakame.

    Author(s):

  • Undaria marching on; late arrival in the Republic of Ireland

    The Asian invasive brown seaweed Undaria pinnatifida was found for the first time in the Republic of Ireland in Kilmore Quay in Co. Wexford in July 2016. As this brown kelp is of considerable economic importance and is cultivated in Asia as well as in Europe, it opens up the discussion if this invasive species is socially acceptable to be cultivated in the Republic of Ireland for food and other purposes. This paper briefly examines the global economic importance, cultivation aspects compared to the European native equivalents such as Alaria esculenta and Saccharina latissima, cultivation yield, economic considerations and the ecological impact of the spread of Undaria into non-native areas. Based on the information and facts presented, it is concluded that Undaria from a physical, social and economic point of view can be cultivated in Ireland.

    Author(s): Stefan Kraan

  • Unconventional high-value products from microalgae: A review

    Microalgae have gained significant importance in biotechnology development, providing valuable goods and services in multiple applications. Although there is a rising market for most of these applications, the incorporation and introduction of microalgae into new venues will extend in the near future. These advances are due to the vast biodiversity of microalgal species, recent genetic engineering tools, and culture techniques. There are three main possible approaches for novel algal compounds from: (1) recently isolated yet less known microalgae; (2) selectively stressed conditions; and (3) enzymatically adjusted compounds from conventional molecules. All these approaches can be combined in a specific manner. This review discusses the opportunities, potential and limitations of introducing novel microalgae-based products, and how the recent technologies can be deployed to make these products financially viable. To give an outlook to the future, an analysis of the developments and predicted future market that further enlarge the promise of cultivating microalgae for commercial purposes are considered.

    Author(s): Said Abu-Ghosh, Zvy Dubinsky, Vitor Verdelho, David Iluz

  • Ulvan: A systematic review of extraction, composition and function

    Species of green macroalgae (Chlorophyta) of the genus Ulva are edible seaweeds with a range of health promoting bioactive components. Ulva is high in dietary fibre which promotes gastrointestinal health and is linked to a reduction in the incidence of chronic diseases. The fundamental active constituent of Ulva is the soluble fibre ulvan, a gelling sulfated polysaccharide with biological activities including immunomodulating, antiviral, antioxidant, antihyperlipidemic and anticancer. Ulvan also has the capacity to modulate cellular signalling processes in both plant and animal systems leading to beneficial effects on productivity and health. Consequently, ulvan is of significant interest as a constituent in human health, agricultural, and biomaterial products. This comprehensive systematic review investigates and recommends acid extraction, ultrafiltration, sugar constituent and molecular weight analysis for the extraction, purification, and characterisation of ulvan, respectively. The biological activities of ulvans are then critically reviewed.

    Author(s): Joel T. Kidgell , Marie Magnusson, Rocky de Nys, Christopher R.K. Glasson

  • Ulvan, a bioactive marine sulphated polysaccharide as a key constituent of hybrid biomaterials: A review

    Ulvan, a sulphated polysaccharide located in the cell walls of green algae that possesses unique structural properties albeit its repeating unit shares chemical affinity with glycosoaminoglycans, such as hyaluronan and chondroitin sulphate, has been increasingly studied over the years for applications in the pharmaceutical field. The increasing knowledge on ulvan’s chemical properties and biological activities has triggered its utilization in hybrid materials, given its potential efficacy in biomedical applications. In the present review, the use of ulvan in the design of different biomaterials, including membranes, particles, hydrogels, 3D porous structures and nanofibers, is presented. The applications of these structures may vary from drug delivery to wound dressing or bone tissue engineering. In this context, general information regarding the structure and chemical variability, extraction processes, physicochemical properties, and biological activities of ulvan is reported.

    Author(s): Leto-Aikaterini Tziveleka, Efstathia Ioannou, Vassilios Roussis

  • Ulva spp. as a natural source of phenylalanine and tryptophan to be used as anxiolytics in fish farming

    Species of the green macroalgae genus Ulva often exhibit rapid growth, are generally cosmopolitan, and are rich in amino acids, vitamins, proteins, and minerals and have high potential for commercial uses. Ulva aquaculture was established and experimentally integrated into fish and shrimp farming in Brazil as Integrated Multi-Trophic Aquaculture projects. Decreases in fish farm production are often due to deaths caused by stress – with consequent increases in production costs. Essential amino acids, such as tryptophan and phenylalanine, have been used in fish farms as anxiolytic agents. In that context, a bibliographic survey was carried out to investigate advances during the last 17 years in the use of tryptophan and phenylalanine produced by Ulva species in fish farming. The biosynthesis patterns of tryptophan and phenylalanine were also examined in the research data. References to the presence of tryptophan and phenylalanine in Ulva spp. were encountered in 32 articles, with Ulva lactuca being the species most cited. References to the use of essential amino acids as anxiolytics in fish farming were encountered in 23 articles, with tryptophan being the most cited; none of the articles, however, mentioned the use of Ulva spp. as sources of anxiolytics. Temperature and pH were the factors that most influenced phenylalanine production. In conclusion, there is a potential role for the use of selected species of Ulva in fish farming as sources of tryptophan and phenylalanine for anxiolytic purposes.

    Author(s): Ana Carolina Calheiros, Renata Perpetuo Reis, Beatriz Castelar, Diana Negrão Cavalcanti, Valéria Laneuville Teixeira

  • Ulva reticulata and Gracilaria crassa : Macroalgae That Can Biofilter Effluent from Tidal Fishponds in Tanzania

    Macroalgae (seaweed) can be cultured effectively for the production of useful algal biomass and removal of nutrients from fishpond effluents. A land-based, tide/gravity-driven flow-through, fish-macroalgae integrated system was studied at Makoba Bay, Zanzibar, Tanzania, during May–October, 2000. Rectangular cages made of 1-inch mesh netting were constructed in channels that received the outflows of the fishponds. Four species of macroalgae were planted in the cages and compared for their usefulness as biofilters. Gracilaria crassa and Ulva reticulata grew at average rates of 1.5 and 1.2 %, respectively. Both species removed nitrogen as seaweed protein at rates of up to 0.4 g N/m2 /d. The algal biomass produced was of good quality with protein dry weight contents of 13% for G. crassa and 26 % for U. reticulata. The biofilters also raised the pH values of the fishpond effluents and oxygenated the water. In contrast to Ulva and Gracilaria, species of Eucheuma and Chaetomorpha performed poorly in the fishpond effluents.

    Author(s): Flower E. Msuya, Amir Neori

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