| 1. |
- Godhe, Anna, 1967, et al.
(författare)
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Intercalibration of classical and molecular techniques for identification of Alexandrium fundyense (Dinophyceae) and estimation of cell densities
- 2007
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Ingår i: Harmful Algae. - : Elsevier BV. - 1568-9883. ; 6:1, s. 56-72
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Tidskriftsartikel (refereegranskat)abstract
- A workshop with the aim to compare classical and molecular techniques for phytoplankton enumeration took place at Kristineberg Marine Research Station, Sweden, in August 2005. Seventeen different techniques - nine classical microscopic-based and eight molecular methods - were compared. Alexandrium fundyense was the target organism in four experiments. Experiment 1 was designed to determine the range of cell densities over which the methods were applicable. Experiment 2 tested the species specificity of the methods by adding Alexandrium ostenfeldii, to samples containing A. fundyense. Experiments 3 and 4 tested the ability of the methods to detect the target organism within a natural phytoplankton community. Most of the methods could detect cells at the lowest concentration tested, 100 cells L-1, but the variance was high for methods using small volumes, such as counting chambers and slides. In general, the precision and reproducibility of the investigated methods increased with increased target cell concentration. Particularly molecular methods were exceptions in that their relative standard deviation did not vary with target cell concentration. Only two of the microscopic methods and three of the molecular methods had a significant linear relationship between their cell count estimates and the A. fundyense concentration in experiment 2, where the objective was to discriminate that species from a morphologically similar and genetically closely related species. None of the investigated methods were affected by the addition of a natural plankton community background matrix in experiment 3. The results of this study are discussed in the context of previous intercomparisons and the difficulties in defining the absolute, true target cell concentration. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Filipsson, H. L., et al.
(författare)
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Seasonal variability of stable carbon isotopes (delta C-13(DIC)) in the Skagerrak and the Baltic Sea: Distinguishing between mixing and biological productivity
- 2017
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Ingår i: Palaeogeography Palaeoclimatology Palaeoecology. - : Elsevier BV. - 0031-0182. ; 483, s. 15-30
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Tidskriftsartikel (refereegranskat)abstract
- We documented the annual cycle of the carbon isotopic composition of dissolved inorganic carbon (delta C-13(DIC)) in the water columns of the Skagerrak and Baltic Sea to obtain an increased understanding of the processes involved controlling the carbon isotopic distribution in shelf seas. The lowest delta C-13(DIC) values (-4.9%.) were found in the low -oxygen, brackish Baltic bottom water whereas the highest values (+1.8%0 were observed in the surface water of the Skagerrak during late summer. Photosynthesis drove the high delta C-13(DIC) values (between 1.0 and 1.8%.) noted in the surface waters of both the Skagerrak and the Baltic. The delta C-13(DIC) values below the halocline in the Baltic reflect mixing of brackish water and the more saline water from the Skagerrak, and foremost organic matter remineralization processes that release significant amounts of low delta C-13 CO2. Similarly, in the stagnant fjord basins, little deep water exchange and the degradation of terrestrial and marine organic matter set the delta C-13 composition. Deep-water renewal in the fjord basins resulted in rapid increases of the delta C-13(DIC) on the order of 1 6., whereas remineralization processes caused a decrease in delta C-13(DIC) of 0.1-03%0 per month depending on location. The combined effects of water mixing and remineralization processes (estimated using apparent oxygen utilization (AOU) values) yielded the expression: delta C-13(DIC=) 0.032 * S = 0.01 * AOU = 0.12 for the Baltic Skagerrak region at water depths below the halocline. (C) 2016 Elsevier B.V. All rights reserved.
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| 3. |
- S, Mortensen, et al.
(författare)
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Summer mortalities and detection of ostreid herpesvirus microvariant in Pacific oysterCrassostrea gigasin Sweden and Norway
- 2016
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Ingår i: Diseases of Aquatic Organisms. - : Inter-Research Science Center. - 0177-5103 .- 1616-1580. ; 117:3, s. 171-176
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Tidskriftsartikel (refereegranskat)abstract
- The Pacific oyster Crassostrea gigas has recently expanded its range in Scandinavia. The expansion is presumably a result of northwards larval drift. Massive settlements were recorded in many areas along the Swedish west coast and southern Norway in 2013 and 2014. After the spawning season in 2014, the temperature of the surface water peaked at 24−26°C. After this period, high and sudden mortalities occurred in a Swedish hatchery and in wild populations along the Swedish west coast and south coast of Norway. Surveys and collected data showed that mortalities mainly occurred during 3 wk in September. All size classes were affected, and affected populations displayed a patchy distribution with heavily affected and unaffected populations in close proximity. Flat oysters Ostrea edulis and blue mussels Mytilus edulis were unaffected. Ostreid herpesvirus (OsHV) was detected in moribund Pacific oyster spat as well as in surviving adults. The virus was identified as OsHV-1 μvar. This is the first detection of this variant in Scandinavia, showing that OsHV-1 μvar is present in areas with recent establishments of Pacific oysters, and where there is no aquaculture of this species.
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