Digital library

  • THE GROWTH OF SPHAGNUM: EXPERIMENTS ON, AND SIMULATION OF, SOME EFFECTS OF LIGHT FLUX AND WATER-TABLE DEPTH

    (1) Experiments were made to determine the effects of both shading and of water-table depth on the growth of three species of Sphagnum. The species (and their usual habitats) depth on the growth of three species of Sphagnum. The species (and their usual habitats) were: S. capillifolium (hummocks); S. paillosum (lawns); and S. recurvum (pools and flushed lawns). 

     

    (2) Water-table depth had little effect on growth measured as increase of dry matter; shading reduced growth and there were specific differences associated with plant size. There were no significant interactions between water-table depth and shading. 

     

    (3) For growth measured as growth in length, there were highly significant interactions, individual species behaving differently in response to shade and, to a lesser extent, in response to water-table depth. 

     

    (4) In Sphagnum lawns in two natural habitats there was a negative correlation between depth of the water-table and surface-roughness. In experimental conditions surface-roughness increased both as the water-table was raised and as shade increased. 

     

    (5) A computer simulation of growth of Sphagnum in a lwan was able to reproduce the observed variations in surface roughness. In mixed lawns of two species, the one in its 'natural' habitat out-grew the other. 

    Author(s): P. M. Hayward, R. S. Clymo

  • The green seaweed Ulva: a model system to study morphogenesis

    Green macroalgae, mostly represented by the Ulvophyceae, the main multicellular branch of the Chlorophyceae, constitute important primary producers of marine and brackish coastal ecosystems. Ulva or sea lettuce species are some of the most abundant representatives, being ubiquitous in coastal benthic communities around the world. Nonetheless the genus also remains largely understudied. This review highlights Ulva as an exciting novel model organism for studies of algal growth, development and morphogenesis as well as mutualistic interactions. The key reasons that Ulva is potentially such a good model system are: (i) patterns of Ulva development can drive ecologically important events, such as the increasing number of green tides observed worldwide as a result of eutrophication of coastal waters, (ii) Ulva growth is symbiotic, with proper development requiring close association with bacterial epiphytes, (iii) Ulva is extremely developmentally plastic, which can shed light on the transition from simple to complex multicellularity and (iv) Ulva will provide additional information about the evolution of the green lineage.

    Author(s): Thomas Wichard, Bénédicte Charrier, Frédéric Mineur, John H. Bothwell, Olivier De Clerck, Juliet C. Coates

  • The Global Water Crisis: Framing the Issue

    In March 2011, high-level experts from around the world were invited to Toronto, Canada, to meet with members of the InterAction Council about the status of the world’s freshwater supply as it relates to global security issues (see List of Participants in this volume). These experts reported that that the global water crisis is real and that there is urgency in addressing the growing number of security risks associated with threatened water supply and quality. They also, however, expressed hope and identified opportunities that can be realized by the timely triggering of change in policies, institutions, and the way society thinks about water.

     

    Author(s): Thomas S. Axworthy, Bob Sandford, Harriet Bigas, Tim Morris, Zafar Adeel

  • The Global Water Crisis: Addressing an Urgent Security Issue

    In March 2011, high-level experts from around the world were invited to Toronto, Canada, to meet with members of theInterAction Council about the status of the world’s freshwater supply as it relates to global security issues (see List ofParticipants in this volume). These experts reported that that the global water crisis is real and that there is urgency inaddressing the growing number of security risks associated with threatened water supply and quality. They also, however,expressed hope and identified opportunities that can be realized by the timely triggering of change in policies, institutions,and the way society thinks about water.

    Author(s): Harriet Bigas , Tim Morris, Bob Sandford, Zafar Adeel

  • The Genus Laminaria Sensu Lato: Recent Insights and Developments

    This review about the genus Laminaria sensu lato summarizes the extensive literature that has been published since the overview of the genus given by Kain in 1979. The recent proposal to divide the genus into the two genera Laminaria and Saccharina is acknowledged, but the published data are discussed under a ‘sensu lato’ concept, introduced here. This includes all species which have been considered to be ‘Laminaria’ before the division of the genus. In detail, after an introduction the review covers recent insights into phylogeny and taxonomy, and discusses morphotypes, ecotypes, population genetics and demography. It describes growth and photosynthetic performance of sporophytes with special paragraphs on the regulation of sporogenesis, regulation by endogenous rhythms, nutrient metabolism, storage products, and salinity tolerance. The biology of microstages is discussed separately. The ecology of these kelps is described with a focus on stress defence against abiotic and biotic factors and the role of Laminaria as habitat, its trophic interactions and its competition is discussed. Finally, recent developments in aquaculture are summarized. In conclusion to each section, as a perspective and guide to future research, we draw attention to the remaining gaps in the knowledge about the genus and kelps in general.

    Author(s): Inka Bartsch Jutta Wiese, Christian Wiencke, Kai Bischof, Cornelia M. Buchholz, Bela H. Buck, Anja Eggert, Peter Feuerpfeil, Dieter Hanelt, Sabine Jacobsen, Rolf Karez, Ulf Karsten, Markus Molis, Michael Y. Roleda, Hendrik Schubert, Rhena Schumann, Klaus Valentin, Florian Weinberger , Florian Weinberger

  • The generic delimitation of Rhodella (Porphyridiales, Rhodophyta) with emphasis on ultrastructure and molecular phylogeny

    We investigated the cellular features and molecular phylogeny ofRhodelia species and related unicellular red algae including undescribed species that we isolated. Results provide a new taxonomic interpretation at both generic and specific levels. The genus Rhodelia is defined by its pyrenoid that is free from any internal structures. Based on phylogenetic analysis using l8SrDNA, there are two possibilities for the generic delimitation ofRhodelia: Rhodelia sensu stricto and Rhodelia sensu lato. The generic autonomy of Dixonielia and the taxonomic position of R. cyanea were also discussed.

    Author(s): Yoshiaki Hara, Kazumichi Sato, Akiko Yokoyama

  • The Future of US Seafood Supply

    The United States today imports most the seafood it consumes. Half of these imports are from aquaculture. Domestic wild capture production is limited and US aquaculture production has declined in recent years. Policy, socioeconomic, and regulatory obstacles stand in the way of expanded US aquaculture production. In this paper, we examine the implications of two future paths for seafood supply: an increasing reliance on imports, and a shift toward increased domestic aquaculture production. We examine global trends, likely future developments in US seafood demand and supply, and implications of the path of US aquaculture development for US seafood supply and prices, employment, ecological footprint, and seafood supply security and safety. We conclude with recommendations for a path forward that serves the interests of the nation and the global community in the search for economically sound and sustainable ways to feed a growing population.

    Author(s): Bruce Morehead, Michael C. Rubino, Hauke Kite-Powell

  • The future of mariculture: a regional approach for responsible development in the Asia-Pacific region

    Aquaculture in the southeast Asian region has been growing steadily over the last few decades, requiring more space to accommodate it. The search for additional areas to expand the aquaculture industry as a whole and the identification of new farming species of commercial value to satisfy the growing local and export markets are pushing the sector in some countries to expand its activities in the sea, including further offshore where more space is available and where, to a lesser extent, competition is currently not so intense. During the latest session of the FAO Committee on Fisheries (COFI) and the Sub-Committee on Aquaculture (COFI-SCA), members requested that FAO look into issues related to the sustainable development of coastal aquaculture and in particular mariculture. The FAO Fisheries and Aquaculture Department in collaboration with the Network of Aquaculture Centres in Asia-Pacific (NACA) organized the regional workshop entitled “The Future of Mariculture: a Regional Approach for Responsible Development in the Asia-Pacific Region” from 7 to 11 March 2006. The workshop, held in Guangzhou, China, was conducted in collaboration with the Bureau of Fisheries of the People’s Republic of China and the Guangdong Ocean and Fisheries Administration. Fifty-one participants from governments, business, non-governmental organizations (NGOs), universities and regional and international organizations from maricultureproducing countries around the Asia-Pacific region attended the workshop.

    The workshop was convened in response to requests from FAO and NACA members to identify key trends and issues affecting mariculture growth in the Asia-Pacific region and to strengthen regional collaboration for future responsible development of mariculture. China’s hosting of the workshop recognizes the status of China as the leading mariculture-producing country in the world and a major market for mariculture products from around the Asia-Pacific region. The workshop was organized in complementary sessions. The first consisted of a series of presentations and discussions on country trends and thematic reviews on selected key issues. The second continued with three working groups focusing on important topics, namely: 1) Market, Demand and Trade; 2) Livelihoods, Producer Organizations, Technology Transfer and Communications; and 3) Mariculture Species and Systems. The third session comprised a “farmer dialogue” and a “trader and marketing dialogue”. The farmer dialogue was conducted at a large mariculture farming area near Guangzhou, while the trader and marketing dialogue was conducted at the largest live-seafood market in Asia. These dialogues yielded valuable insights and recommendations from farmers and traders.

    The final plenary session brought together the working group findings and identified opportunities for regional collaborative action. The workshop participants proposed the establishment of a regional “Asia-Pacific Mariculture Cooperation” initiative to support the development of sustainable mariculture in the Asia-Pacific region. The initiative will facilitate cooperation among the countries of the region by promoting responsible mariculture farming technologies, capacity-building, market access and effective transfer of knowledge. The platform for the initiative would be the “Asia-Pacific Marine Finfish Aquaculture Network”, which is already promoting cooperation in marine fish farming around the region and has been widely seen as a successful programme. FAO and NACA were requested to facilitate and support the development of this new mariculture initiative.

    Author(s): Alessandro Lovatelli, Micheal J. Phillips, J. Richard Arthur, Koji Yamamoto

  • The Future of Aquatic Protein: Implications for Protein Sources in Aquaculture Diets

    Approximately 70% of the aquatic-based production of animals is fed aquaculture, whereby animals are provided with high-protein aquafeeds. Currently, aquafeeds are reliant on fish meal and fish oil sourced from wild-captured forage fish. However, increasing use of forage fish is unsustainable and, because an additional 37.4 million tons of aquafeeds will be required by 2025, alternative protein sources are needed. Beyond plant-based ingredients, fishery and aquaculture byproducts and insect meals have the greatest potential to supply the protein required by aquafeeds over the next 10–20 years. Food waste also has potential through the biotransformation and/or bioconversion of raw waste materials, whereas microbial and macroalgal biomass have limitations regarding their scalability and protein content, respectively. In this review, we describe the considerable scope for improved efficiency in fed aquaculture and discuss the development and optimization of alternative protein sources for aquafeeds to ensure a socially and environmentally sustainable future for the aquaculture industry.

    Author(s): Katheline Hua, Jennifer M. Cobcroft, Andrew Cole, Kelly Condon, Dean R. Jerry, Arnold Mangott, Christina Praeger, Matthew J. Vucko, Chaoshu Zeng, Kyall Zenger, Jan M. Strugnell

  • The freshwater macroalga Oedogonium intermedium can meet the nutritional requirements of the herbivorous fish Ancistrus cirrhosus

    The macroalga Oedogonium intermedium has a diverse elemental profile, high energy potential, high lipid content, a high proportion of essential amino acids and a total concentration of protein with the potential to meet the nutritional requirements of herbivorous fishes. The aim of this study was to assess growth, condition, colouration and reproductive output in an herbivorous ornamental fish. The catfish Ancistrus cirrhosus was fed one of three pelletised experimental feeds, Oedogonium, a formulated commercial feed and a 50:50 mix of the two, over a 10 month trial. After 10 months, fish that were fed exclusively on Oedogonium had equivalent growth rates, body condition, colouration, fecundity and fertilisation rates compared to those fed the commercial and mixed feeds. The absence of any major differences of these characteristics between feeds, especially between Oedogonium and the commercial feed, demonstrates the viability of Oedogonium as a feed, or significant feed ingredient, for this herbivorous fish. As such, linking the cultivation of Oedogonium with the production of herbivorous fish may provide an ideal application for Oedogonium.

    Author(s): Matthew J. Vucko, Andrew J. Cole, Jonathan A. Moorhead, Josiah Pit, Rocky de Nys

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