Scottish Association for Marine Science

About: Scottish Association for Marine Science is a facility organization based out in Oban, United Kingdom. It is known for research contribution in the topics: Sea ice & Benthic zone. The organization has 524 authors who have published 1765 publications receiving 70783 citations. The organization is also known as: SAMS & Scottish Marine Station for Scientific Research.

Copper-induced inhibition of photosynthesis: limiting steps of in vivo copper chlorophyll formation in Scenedesmus quadricauda

Abstract: The in vivo substitution of Mg2+ in chlorophyll by heavy metals is an important damage mechanism in heavy metal-stressed plants that leads to an inhibition of photosynthesis. In photosynthetic organisms with LHC II antennae, the in vivo substitution of Mg2+ by Cu2+ occurs particularly readily under low irradiance with a dark phase - a phenomenon referred to as 'shade reaction'. In the present study the limiting steps of the shade reaction were investigated with synchronised cultures of the chlorococcal green alga Scenedesmus quadricauda (Turp.) Breb. The rate of copper chlorophyll formation during shade reaction was shown to be controlled by several factors; firstly, in some phases of the cell cycle, especially at the end of the light period, Mg2+ in chlorophyll was not accessible to substitution. This pattern is likely to be caused by cell cycle-dependent changes in photosynthesis and thylakoid ultrastructure, which were published earlier and are reconsidered in the discussion of the present work. Secondly, prolonged culture in a medium containing 3 μM Cu2+ reversibly increased the resistance of the strain to Cu2+. Culturing without added Cu2+ lowered the threshold concentrations of various deleterious effects more than 10-fold within 8 months of de-adaptation. Adaptation to high Cu2+ levels is discussed in the context of studies of the regulation of metal transporter proteins. In addition, it was also observed that toxic Cu2+ levels impaired photosynthesis sooner than cell division.

Integrating deliberative monetary valuation, systems modelling and participatory mapping to assess shared values of ecosystem services

Abstract: There is increasing recognition of the need to unite analytical and participatory methodologies to establish more comprehensive valuations of ecosystem services and move beyond individual conceptions of value. This research integrates a three-stage choice experiment with participatory systems modelling, participatory mapping and psychometric analysis in a coastal case study in Scotland. It aimed to explore contrasts between individual willingness to pay and shared values expressed as group-deliberated fair prices, how deliberation on social-ecological systems would impact on value formation, and how participatory mapping might elicit distinct values not reflected in the monetary valuation. Results indicated marked differences between individual and deliberated group values, with deliberated individual values falling between the two. The systems modelling intervention combined with explicit discussion of transcendental values (life goals and guiding principles) generated significant learning and helped to better reflect transcendental values in monetary values. The deliberations and fair price framing shifted participants towards a public policy perspective, balancing benefit trade-offs with questions of fairness and responsibility. The highly localised nature of many values expressed through participatory mapping suggests that many of these places-based values would have been under-recognised by monetary valuation alone.

Glycoprotein emulsifiers from two marine Halomonas species: chemical and physical characterization.

Abstract: Aims: To partially purify and characterize bioemulsifiers produced by two new marine Halomonas species, TG39 and TG67, and to compare their emulsifying activities with those of commercial emulsifiers. Methods and Results: The production of emulsifiers HE39 and HE67 was achieved from glucose-supplemented marine broth, and recovered by cell removal, concentration by ultrafiltration, precipitation with salt and ethanol, and lyophilization. Purification and chemical analysis revealed both emulsifiers to be glycoproteins of high molecular weight with a notably high content of protein and uronic acids. Physical characterization showed both glycoproteins to effectively emulsify a wide range of food oils under both neutral and acidic pH conditions and withstand acid and high temperature treatment. Conclusions: The emulsifying activities of these two new glycoprotein emulsifiers were comparable and, under certain conditions, superior to those produced by commercial emulsifiers tested (xanthan gum, gum arabic and lecithin). They show the highest reported emulsifying activities derived from a Halomonas species. Significance and Impact of the Study: These strains, and the emulsifiers produced, appear to be promising candidates for further development in applications requiring emulsifiers that are natural and compatible to the existing commercial emulsifiers.

Feeding and overwintering of Antarctic krill across its major habitats: The role of sea ice cover, water depth, and phytoplankton abundance

Abstract: Antarctic krill (Euphausia superba) were sampled in contrasting habitats: a seasonally ice-covered deep ocean (Lazarev Sea), ice-free shelves at their northern range (South Georgia) and the Antarctic Peninsula (Bransfield Strait), and shelf and oceanic sites in the Scotia Sea. Across 92 stations, representing a year-round average, the food volume in krill stomachs comprised 71 6 29% algae, 17 6 21% protozoans, and 12 6 25% metazoans. Fatty acid trophic markers showed that copepods were consistently part of krill diet, not a switch food. In open waters, both diatom and copepod consumption increased with phytoplankton abundance. Under sea ice, ingestion of diatoms became rare, whereas feeding on copepods remained constant. During winter, larvae contained high but variable proportions of diatom markers, whereas in postlarvae the role of copepods increased with krill body length. Overwintering differed according to habitat. Krill from South Georgia had lower lipid stores than those from the Bransfield Strait or Lazarev Sea. Feeding effort was much reduced in Lazarev Sea krill, whereas most individuals from the Bransfield Strait and South Georgia contained phytoplankton and seabed detritus in their stomachs. Their retention of essential body reserves indicates that krill experienced most winter hardship in the Lazarev Sea, followed by South Georgia and then Bransfield Strait. This was reflected in the delayed development from juveniles to adults in the Lazarev Sea. Circumpolar comparisons of length frequencies suggest that krill growth conditions are more favorable in the southwest Atlantic than in the Lazarev Sea or off East Antarctica because of longer phytoplankton bloom periods and rewarding access to benthic food.