| 1. |
- Brutemark, Andreas, et al.
(author)
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Carbon isotope signature variability among cultured microalgae: Influence of species, nutrients and growth
- 2009
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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 372:1-2, s. 98-105
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Journal article (peer-reviewed)abstract
- In this study we have investigated whether the carbon isotopic signature differs between different groups and species of marine phytoplankton depending on growth phase, nutrient conditions and salinity. The 15 investigated algal species, representing the Bacillariophyceae, Chlorophyceae, Cryptophyceae, Cyanophyceae, Dinophyceae and Haptophyceae classes were grown in batch monocultures and analysed for delta C-13 in both exponential and stationary phase. For all the cultured species, delta C-13 signatures ranged from -23.5 parts per thousand (Imantonia sp.) to - 12.3 parts per thousand (Nodulania spumigena) in the exponential phase and from - 18.8 parts per thousand (Amphidinium carterae) to - 8.0 parts per thousand (Anabaena lemmermannii) in the stationary phase. Three species (Dunaliella tertiolecta, Rhodomonas sp.. Heterocapsa triquetra) were also grown under nutrient sufficient and nitrogen or phosphorus deficient conditions. Nitrogen limitation resulted in a more negative delta C-13 signature, whereas no effect could be observed during phosphorus limitation compared to nutrient sufficient conditions. Growth of Prymnesium parvum in two different salinities resulted in a more negative delta C-13 signature in the 26 parts per thousand-media compared to growth in 7 parts per thousand-media. Our results show that the carbon isotopic signature of phytoplankton may be affected by salinity, differ among different phytoplankton species, between exponential and stationary phase, as well as between nutrient treatments. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Carlsson, Per, et al.
(author)
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Bacterial and phytoplankton nutrient limitation in tropical marine waters, and a coastal lake in Brazil
- 2012
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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 418, s. 37-45
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Journal article (peer-reviewed)abstract
- Bioassay experiments were performed two times (with 2 years in between) in order to investigate if nitrogen (N, ammonium), phosphorus (P, phosphate) and carbon (C, glucose) additions would stimulate the growth of bacteria and phytoplankton differently in three different tropical aquatic environments. The water and their indigenous microbial communities were taken from a freshwater coastal lake (Cabiunas), a coastal (Anjos), and an offshore marine station (Sonar) in the Atlantic outside Cabo Frio, Rio de Janeiro State, Brazil. Ammonium, phosphate and glucose were added alone or in combination to triplicate bottles. In the lake, P seemed to be the primary limiting factor during the first experiment, since both bacterial production and phytoplankton growth was stimulated by the P addition. Two years later, however, addition of P inhibited phytoplankton growth. During both years, C was closely co-limiting for bacteria since CP additions increased the response considerably. For both the coastal and offshore seawater stations, phytoplankton growth was clearly stimulated by N addition in both years and the bacteria responded either to the P, N or C additions (alone or in combination). To conclude, the results from these tropical aquatic systems show that it is possible that phytoplankton and bacteria may compete for a common resource (P) in lakes, but can be limited by different inorganic nutrients in marine waters as well as lakes, suggesting that phytoplankton and bacteria do not necessarily compete for the same growth limiting nutrient in these environments. (C) 2012 Elsevier B.V. All rights reserved.
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| 3. |
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| 6. |
- Granéli, Edna, et al.
(author)
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Nitrogen in Inland Seas
- 2008. - 2nd Edition
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In: Nitrogen in the Marine Environment. - San Diego : Academic Press. - 9780123725226
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Book chapter (other academic/artistic)
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| 7. |
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| 8. |
- Granéli, Edna, et al.
(author)
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Nutrient limitation of primary production in the Baltic Sea area
- 1990
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In: Ambio. - 0044-7447 .- 1654-7209. ; 19:3, s. 142-151
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Journal article (peer-reviewed)abstract
- In the Baltic Sea area, including the Kattegat, the external N/P loadingratios are generally well above the 16:1 Redfield ratio for all subareas (theBothnian Bay, the Bothnian Sea, the Baltic proper and the Kattegat).During winter, the inorganic N/P ratio in surface waters varies. Appreciablyhigher values than the loading ratio are found for the northernmostbasin, the low-saline Bothnian Bay, while lower values than the loadingratio are found for the Baltic proper and the Kattegat. Nutrient enrichmenttests indicate general N limitation in the Baltic proper and the Kattegat,although stimulation of algal growth after P enrichment has been found inthe Baltic proper during summer blooms of blue-green algae. Blooms ofblue-green algae are common in the Baltic proper but hardly ever occur inthe Bothnian Bay and the Kattegat. This has been the case for the lastcentury, indicating natural summer N limitation. Full-scale experimentalmanipulation of the external N/P loading ratio has been carried out in theHimmerfjard basin, south of Stockholm. Results suggest nitrogen as themost limiting nutrient in coastal areas of the Baltic proper, uninfluencedby direct nutrient discharges. The knowledge of the effects of alteredexternal nutrient supplies for nutrient limitation in the Baltic Sea systemas a whole is too limited to allow for reliable predictions. However, theBaltic Sea may have developed towards a more pronounced N limitationdue to a twofold historic increase in P supply relative to N supply. Atpresent, the situation may be reversed as N supply is probably increasingmore rapidly than P supply. Management of the Baltic Sea area cannot bebased on removal of either N or P in sewage, but must take both elementsinto consideration, as well as differences between sub-basins andbetween polluted coastal and offshore areas.
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| 13. |
- Granéli, W., et al.
(author)
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Automatic potentiometric determination of dissolved oxygen
- 1991
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In: Marine Biology. - 0025-3162 .- 1432-1793. ; 108:2, s. 341-348
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Journal article (peer-reviewed)abstract
- Commercially available automatic titration systems were tested in 1988 for potentiometric titration of liberated iodine by the Winkler method of oxygen determination. The potentiometric equivalence point was also compared to the manual starch end point. Finally the automatic method was used in order to estimate below-halocline respiration in the Kattegat, Sweden. Standard deviations of 0.007 ml O2 l-1 or 0.1 to 0.3% coefficients of variation (% standard deviation of the mean) were achieved when titrating 25 ml from replicate 60-ml oxygen bottles using the automatic method, or 50 ml manually. The precision for replicate titrations of 50-ml aliquots of 0.001 N KIO3 was < 0.05% (0.002 ml 0.01 N Na2S2O3) for the automatic method. Titration time for 25-ml aliquots was 2 to 4 min, somewhat longer than for manual titrations (1 to 1.5 min). However, during titration the operator is free to perform other tasks. It is not possible to use automatic sample changers, due to rapid iodine volatilization. The equipment can be handled by relatively unskilled analysts and is suitable for use on board research vessels or in field stations [weight for a Mettler(TM) titrator (Mettler Instrumente AG, Greifensee, Switzerland) < 10 kg, volume < 0.1 m3]. Below-halocline oxygen consumption in the SE Kattegat ranged from 0 to 6 ml O2 m-3 h-1 (mean values for September and October 1988 = 1.69 and 0.66 ml O2 m-3 h-1, respectively, with 95% confidence limits of ca. +/- 0.6 ml O2 m-3 h-1).
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| 14. |
- Lindehoff, Elin, et al.
(author)
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Effect of tertiary sewage effluent additions on Prymnesium parvum cell toxicity and stable isotope ratios
- 2009
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In: Harmful Algae. - : Elsevier BV. - 1878-1470 .- 1568-9883. ; 8:2, s. 247-253
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Journal article (peer-reviewed)abstract
- We investigated the ability of the ichthyotoxic haptophyte Prymnesium parvum to use sewage-originated nutrients applying stable carbon (C) and nitrogen (N) isotope techniques. P. parvum was cultured under N and phosphorus (P) sufficient and deficient conditions in either sewage effluent-based medium or in a nitrate- and phosphate-based control. Cell densities and toxicities were monitored and stable carbon N isotopes signatures (delta C-13 and delta N-15) of P. parvum and the sewage effluent analysed. Nitrogen and P sufficient cultures achieved the highest biomass followed by P and N deficient cultures, regardless of sewage effluent additions. The P deficient cultures with sewage effluent had higher toxicity, estimated as haemolytic activity (9.4 +/- 0 x 10(-5) mg Saponin equiv. cell(-1)) compared to the P deficient control and to all N deficient and NP sufficient cultures. Nutrient deficient conditions had no effect on the cell delta N-15, but a decreasing effect on delta C-13 in the inorganic N deficient treatment. Growth in sewage-based media was followed by a substantial increase in the cell delta N-15 (10.4-16.1.60) compared to the control treatments (2.4-4.9%o), showing that P. parvum is capable of direct use of sewage-originated N, inorganic as well as organic. Uptake of terrestrial derived C in the sewage treatments was confirmed by a decrease in cell delta C-13, implying that P. parvum is able to utilize organic nutrients in sewage effluent. (C) 2008 Elsevier B.V. All rights reserved.
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| 18. |
- Barreiro, A, et al.
(author)
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Relative importance of the different negative effects of the toxic haptophyte Prymnesium parvum on Rhodomonas salina and Brachionus plicatilis
- 2005
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In: Aquatic Microbial Ecology. - : Inter-Research Science Center. - 0948-3055 .- 1616-1564. ; 38:3, s. 259-267
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Journal article (peer-reviewed)abstract
- The aim of this study was to determine the relative importance of the different processes/mechanisms by which the toxic haptophyte Prymnesium parvum, cultured under different nutrient conditions, affects non-toxic phytoplankton competitors and microzooplankton grazers. P. parvum was cultured under steady-state growth in different nutrient conditions: nitrogen depleted (-N), phosphorus depleted (-P) and balanced nitrogen and phosphorus (+NP). Cells from each nutrient condition and culture cell-free filtrates, alone and combined with non-toxic prey (Rhodomonas salina), were used as food for the rotifer Brachionus plicatilis. An additional experiment was carried out to test the effect of P. parvum cells and culture cell-free filtrate on R. salina. The highest haemolytic activity values were achieved by -P F parvum cultures, followed by -N. However, the negative effect of R parvum on R. salina and rotifers did not correlate with haemolytic activity but with the number of P. parvum cells. -N-cultured P. parvum were the most toxic for both R. salina and rotifers, followed by +NP. Therefore, haemolytic activity is not a good indicator of the total potential toxicity of R parvum. The growth rate of R. salina was negatively affected by cell-free filtrates but the effect of P, parvum predation was greater. Rotifers fed on both toxic and non-toxic algae, indicating that they did not select against the toxic alga. The P. parvum cell-free filtrate had an effect on B. plicatilis, although this was weak, B, plicatilis was also indirectly affected by P. parvum due to the negative effects of the toxic alga on their prey (R. salina). However, the greatest negative effect of P. parvum on the rotifers was due to ingestion of the toxic cells. Therefore, the phytoplankton competitor R. salina is more affected by P. parvum predation and the grazer B. plicatilis is more affected by ingestion of the toxic cells, the effects of excreted compounds being secondary.
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| 19. |
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| 20. |
- Bowers, HA, et al.
(author)
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Combining flow cytometry and real-time PCR methodology to demonstrate consumption in Prymnesium parvum
- 2010
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In: Journal of the American Water Resources Association. - : Wiley. - 1093-474X .- 1752-1688. ; 46, s. 133-143
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Journal article (peer-reviewed)abstract
- Harmful algal bloom species can persist in the environment, impacting aquatic life and human health. One of the mechanisms by which some harmful algal bloom species are able to persist is by consumption of organic particles. Methods to demonstrate and measure consumption can yield insight into how populations thrive. Here, we combine flow cytometry and real-time PCR to demonstrate consumption of a cryptophyte species (Rhodomonas sp.) by a toxic mixotrophic haptophyte (Prymnesium parvum). Using flow cytometry, the feeding frequency of a population of P. parvum cells was calculated using the phycoerythrin (PE) fluorescence signal from Rhodomonas sp. and the fluorescence of an acidotropic probe labeling the food vacuoles. Feeding frequency increased in the beginning of the experiment and then began to decline, reaching a maximum of 47.5% of the whole P. parvum population after 212 min. The maximum number of consumed Rhodomonas sp. cells was 0.8 per P. parvum cell, and occurred after 114 min corresponding to an ingestion rate of 0.4 Rhodomonas sp. cells/P. parvum/h. Cells from the feeding P. parvum population were sorted, washed, and subjected to a real-time PCR assay targeting the cryptophyte 18S locus. There was a correlation between cycle threshold (Ct) values and number of consumed prey cells calculated by fluorescence. Overall, this study shows that flow cytometric analysis, of the acidotropic probe and prey pigments, is an efficient and rapid tool in enumerating food vacuoles and the number of prey cells consumed. Furthermore, we suggest that real-time PCR can be applied to cells sorted by flow cytometry, thus allowing for the detection and potential quantification of the targeted prey cells.
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| 21. |
- Brutemark, Andreas, et al.
(author)
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Role of mixotrophy and light for growth and survival of the toxic haptophyte Prymnesium parvum
- 2011
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In: Harmful Algae. - : Elsevier BV. - 1568-9883 .- 1878-1470. ; 10, s. 388-394
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Journal article (peer-reviewed)abstract
- Mixotrophy in Prymnesium parvum was investigated using carbon (δ13C) and nitrogen (δ15N) stable isotopes. The experiment was performed in light and dark. In the dark treatment we expected that the mixotrophic P. parvum would rely solely on its prey and therefore reflect the prey isotopic signatures. In the light treatment P. parvum can perform photosynthesis as well as utilize its prey, thus we expect the isotopic signatures to be between the dark mixed cultures and the monocultures, depending on how much prey was utilized. In the light treatment, addition of the ciliate Myrionecta rubra resulted in higher P. parvum cell numbers compared to monocultures. During the experiment, cell numbers in the dark monocultures and the mixed dark cultures did not increase. P. parvum had 2.5-3 times higher cellular phosphorus and nitrogen content in the dark compared to the cultures in the light whereas no difference in carbon content between treatments could be observed. This suggests that P. parvum can utilize nitrogen and phosphorus but not carbon in the dark. It thus seems as if P. parvum relies on photosynthesis to meet the carbon and energy demand required for growth. The expected isotopic signatures “become what you eat…plus a few per mil” were not observed. In the dark treatment, the δ13C did not differ between monocultures and mixed cultures. In the light treatments P. parvum δ13C became less negative then the corresponding dark treatments indicating that P. parvum used CO2 rather than carbon from the added prey. No difference in δ15N between monocultures and mixed cultures could be observed during the experiment. We argue that light is necessary for P. parvum growth and that the ability to utilize nutrients originating from their prey may be important in bloom formation.
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