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.

Distinction between multiple isolates of chlorella vulgaris (chlorophyta, trebouxiophyceae) and testing for conspecificity using amplified fragment length polymorphism and its rdna sequences†

Abstract: Multiple strains of individual algal species are available from public culture collections, often with the same isolate being maintained in parallel at a number of collections under different culture regimes. To unravel genomic variation and to identify unique genotypes among such multiple strains, two approaches were used on a sample of 29 strains of Chlorella vulgaris Beijerinck, an alga of great value for applied research, from five culture collections. With the exception of two strains, internal transcribed spacer rDNA sequence data substantiated conspecificity of the studied strains and only minor sequence differences with the authentic "Beijerinck isolate" were observed. Amplified fragment length polymorphism (AFLP) detected considerable genomic variation when rDNA sequences were identical. Band detection and the construction of a binary matrix from AFLP patterns for phylogenetic analyses were fully automated, but comparison of similar patterns still required manual refinement. The AFLPs distinguished 11 unique genotypes and provided robust support for the presence of five cryptic species. This finding advocates the need to carefully record which strain has been used in any experiment or in applied research, because genomic variation may also correspond to differences in physiological/biochemical properties. No genomic differences could be detected between duplicate strains of the same isolate that were maintained by continuous subculturing over many decades or within those stored at ultralow temperatures.

Multiscale Observations of Deep Convection in the Northwestern Mediterranean Sea during Winter 2012–2013 Using Multiple Platforms

Abstract: During winter 2012–2013, open‐ocean deep convection which is a major driver for the thermohaline circulation and ventilation of the ocean, occurred in the Gulf of Lions (Northwestern Mediterranean Sea) and has been thoroughly documented thanks in particular to the deployment of several gliders, Argo profiling floats, several dedicated ship cruises, and a mooring array during a period of about a year. Thanks to these intense observational efforts, we show that deep convection reached the bottom in winter early in February 2013 in a area of maximum 28 ± 3 109 m2. We present new quantitative results with estimates of heat and salt content at the subbasin scale at different time scales (on the seasonal scale to a 10 days basis) through optimal interpolation techniques, and robust estimates of the deep water formation rate of 2.0 ± 0.2 Sv. We provide an overview of the spatiotemporal coverage that has been reached throughout the seasons this year and we highlight some results based on data analysis and numerical modeling that are presented in this special issue. They concern key circulation features for the deep convection and the subsequent bloom such as Submesoscale Coherent Vortices (SCVs), the plumes, and symmetric instability at the edge of the deep convection area.

Late Quaternary contourites and glaciomarine sedimentation in the Fram Strait

Abstract: Two sites in the eastern Fram Strait, the Vestnesa Ridge and the Yermak Plateau, have been surveyed and sampled providing a depositional record over the last glacial-interglacial cycle. The Fram Strait is the only deep-water connection from the Arctic Ocean to the North Atlantic and contains a marine sediment record of both high latitude thermohaline flow and ice sheet interaction. On the Vestnesa Ridge, the western Svalbard margin, a sediment drift was identified in 1226 m of water. Gravity and multicores from the crest of the drift recovered turbidites and contourites. 14C dating indicates an age range of 8287 to 26 900 years BP (Early Holocene to Late Weichselian). The Yermak Plateau is characterized by slope sediments in 961 m of water. Gravity and multicores recovered contourites and hemipelagites. 14C ages were between 8615 and 46 437 years BP (Early Holocene to mid-Weichselian). Downcore dinoflagellate cyst analyses from both sites provide a record of changing surface water conditions since the mid-Weichselian, suggesting variable sea ice extent, productivity and polynyas present even during the Last Glacial Maximum. Four layers of ice-rafted debris were also identified and correlated within the cores. These events occurred ca at 9, 24 to 25, 26 to 27 and 43 ka, asynchronous with Heinrich layers in the wider north-east Atlantic and here interpreted as reflecting instability in the Svalbard/Barents Ice sheet and the northward advection of warm Atlantic water during the Late Weichselian. The activity of the ancestral West Spitsbergen Current is interpreted using mean sortable silt records from the cores. On the Vestnesa Ridge drift the modern mass accumulation rate, calculated using excess 210Pb, is 0·076 g cm−2 year−1. On the Yermak Plateau slope the modern mass accumulation rate is 0·053 g cm−2 year−1.

Saturating light and not increased carbon dioxide under ocean acidification drives photosynthesis and growth in Ulva rigida (Chlorophyta)

Abstract: Carbon physiology of a genetically identified Ulva rigida was investigated under different CO2(aq) and light levels. The study was designed to answer whether (1) light or exogenous inorganic carbon (Ci) pool is driving growth; and (2) elevated CO2(aq) concentration under ocean acidification (OA) will downregulate CAext-mediated dehydration and alter the stable carbon isotope (δ13C) signatures toward more CO2 use to support higher growth rate. At pHT 9.0 where CO2(aq) is <1 μmol L−1, inhibition of the known use mechanisms, that is, direct uptake through the AE port and CAext-mediated dehydration decreased net photosynthesis (NPS) by only 56–83%, leaving the carbon uptake mechanism for the remaining 17–44% of the NPS unaccounted. An in silico search for carbon-concentrating mechanism elements in expressed sequence tag libraries of Ulva found putative light-dependent transporters to which the remaining NPS can be attributed. The shift in δ13C signatures from –22‰ toward –10‰ under saturating light but not under elevated CO2(aq) suggest preference and substantial use to support photosynthesis and growth. U. rigida is Ci saturated, and growth was primarily controlled by light. Therefore, increased levels of CO2(aq) predicted for the future will not, in isolation, stimulate Ulva blooms.