Glacial vicariance is regarded as one of the most prevalent drivers of phylogeographic structure and speciation among high-latitude organisms, but direct links between ice advances and range fragmentation have been more difficult to establish in marine than in terrestrial systems. Here we investigate the evolution of largely disjunct (and potentially reproductively isolated) phylogeographic lineages within the amphi-boreal kelp Saccharina latissima s. l. Using molecular data (COI, microsatellites) we confirm that S. latissima comprises also the NE Pacific S. cichorioides complex and is composed of divergent lineages with limited range overlap and genetic admixture. Only a few genetic hybrids were detected throughout a Canadian Arctic/NW Greenland contact zone. The degree of genetic differentiation and sympatric isolation of phylogroups suggest that S. latissima s. l. represents a complex of incipient species. Phylogroup distributions compared with paleo-environmental reconstructions of the cryosphere further suggest that diversification within S. latissima results from chronic glacial isolation in disjunct persistence areas intercalated with ephemeral interglacial poleward expansions and admixture at high-latitude (Arctic) contact zones. This study thus supports a role for glaciations not just in redistributing pre-existing marine lineages but also as a speciation pump across multi-glacial cycles for marine organisms otherwise exhibiting cosmopolite amphi-boreal distributions.
Digital library
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The Global Aquaculture Advocate is a four-color trade magazine focused on efficient and responsible aquaculture throughout the world. Written by and for professionals from all farmed seafood sectors, “The Global Magazine for Farmed Seafood” features a range of culture species in articles valued for both their technical content and informative perspectives.
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Report by the Institution of Mechanical Engineers found that due to poor practices in harvesting, storage and transportation, as wellvas market and consumer wastage, it is estimated that 30–50% (or 1.2–2 billion tonnes) of all food produced never reaches a human stomach.
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Discussion on:
- Nutrient releases from salmon aquaculture
- Impacts on pelagic ecosystems
- Pelagic nutrient and ecosystems impacts of salmon aquaculture in Chile, with emphasis on dissolved nutrient loading and harmful algal blooms
- Salmon aquaculture and harmful algal blooms (HABs)
- Nutrient impacts of salmon aquaculture on Chilean lakes
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- This factsheet is based on FAO statistics on aquaculture and fisheries production. The data and statistics, which were the most updated at the time when the factsheet was prepared, may differ from data and statistics used in other WAPI factsheets because of different data sources or different versions of the same dataset. They may not be consistent with data and statistics from other sources.
- The term “country” used in this factsheet includes non-sovereign territory. The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
- The factsheet follows the grouping of Landlocked Developing Countries and Small Island Developing States (SIDS) adopted by the UN Office of the High Representative for the Least Developed Countries, Landlocked Development countries and Small Island Developing States (UN-OHRLLS): http://unohrlls.org/about-sids/country-profiles/. Unless noted otherwise, other country grouping in this factsheet follows the United Nations M49 standard.
- The preparation of the factsheet has benefited from tables and charts generated by various World Aquaculture Performance Indicator (WAPI) modules. Most of these data analysis tools are for FAO internal use, yet some of them are available for test use. Visit the WAPI webpage for more information about WAPI information and knowledge products.
- The factsheet was prepared by Junning Cai and Giulia Galli. Valuable comments and suggestions provided by Esther Garrido Gamarro and Giorgos Paximadis are acknowledged. The validity and relevance of the results depend on the quality (in terms of timeliness and accuracy) of the underlying data and statistics used in the analyses. Errors could also occur in the analyses despite our efforts to minimize them. Simple text are provided to help users understand the tables and charts. Users may use the original data sources to verify the results. We welcome your feedback to help us improve the factsheet.
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Species of the unicellular alga Dunaliella possess outstanding tolerance of a wide range of salinities. They can adapt to grow in salt media which range from less than 0.5 M to saturated salt solutions and withstand enormous osmotic shocks through a unique osmotic adaptation. The osmoregulating mechanism depends on photosynthetic production of glycerol, whose intracellular concentration varies in direct proportion to the extracellular salt concentration and reaches values in excess of 50% of the total dry weight of the cells. Dunaliella, and another halotolerant glycerol producing alga, Asteromonas gracilis, osmoregulate biochemically by controlling glycerol biosynthesis and degradation. 3 new enzymes, NADPH-dihydroxyacetone-reductase, dihydroxyacetone kinase and glycerol-1-phosphatase seem to be involved in the osmoregulatory response via glycerol in Dunaliella and Asteromonas. A hypothetical scheme of glycerol metabolism in these algae utilizing these enzymes is presented. Growth studies of Dunaliella indoors and outdoors showed that salt concentrations favoring maximal glycerol productivity are not identical with those required for maximal algal productivity. Maximal yield of glycerol occurred around 2 M NaCl while maximal algal productivity occurred below 0.5 M NaCl. Observed yields of glycerol in Dunaliella culture outdoors are compared with theoretically calculated maximal yield.
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Glyphosate-based herbicides are commonly used to combat weeds and unwanted grasses in many habitats in the Hawaiian Islands, including near freshwater, marine, and anchialine pond shorelines. Glyphosate is reported to degrade within a few days of application and to break down rapidly in soil, which suggests that it is safe for use near aquatic environments. However, glyphosate can be transported to coastal waters, especially during run-off events. Five native macroalgael and seagrass species and one introduced aquatic vascular plant found in coastal anchialine ponds or in the adjacent intertidal zone were exposed to freshly mixed solutions of a glyphosate-based herbicide in lab experiments. Chlorophyll absorbance and photosystem II (PSII) efficiency were measured after 5 to 7 days of incubation. At herbicide concentrations (0.225 to 1.8 g L−1 glyphosate) below the manufacturer’s lowest recommended concentration (3.6 g L−1 glyphosate), chlorophyll absorbance and PSII efficiency differed significantly from the control (0.0 g L−1 glyphosate). Native macroalgae and seagrasses in marine and anchialine aquatic habitats may be negatively affected by use of glyphosate herbicides to control shoreline weeds.
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Scientists have created a genetically engineered microbe that turns the algae into low-carbon biofuel, but must make the technique commercially viable
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The Seaweed Carrier mimics a natural seaweed, moving freely in the sea from a single mooring point. Testing with a small-scale carrier in Frøya in July 2011 reveals promise.
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A significant challenge to the expansion of aquaculture production is controlling the outbreak of disease. Many farmers who experience the potential loss of stock from disease may choose to use chemotherapeutic agents to minimize their loss. It is generally understood that a disease in aquaculture is a combination of the health of the animal, the condition of the environment and the presence of a pathogen. From this concept there are a number of precautionary measures that farmers may practice to minimize disease outbreaks. The principles of Hazard Analysis Critical Control Point (HACCP) may be useful risk management tools to reduce pathogens, animal stress and the need for chemotherapeutic agents to control disease outbreaks on the farm.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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