| 1. |
- Al-Handal, Adil Y, 1952, et al.
(författare)
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COCCONEIS POTTERCOVEI SP NOV AND COCCONEIS PINNATA VAR. MATSII VAR. NOV., TWO NEW MARINE DIATOM TAXA FROM KING GEORGE ISLAND, ANTARCTICA
- 2010
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Ingår i: Diatom Research. - 0269-249X. ; 25:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Details of two new small marine taxa of the genus Cocconeis Ehrenberg are described; C. pottercovei sp. nov. and C. pinnata var. matsii var. nov., which were observed as epipelic and epiphytic in Potter Cove, King George Island, Antarctica. Descriptions are based on both light and scanning electron microscope observations. C. pottercovei belongs to the group of Cocconeis taxa that bear very short and marginal striae on the rapheless valve while C. pinnata var. matsii belongs to the C. costata Gregory complex. They are mainly differentiated from the other similar taxa by stria number, stria arrangement and structure on both raphe and rapheless valves. A comparison with closely resembling taxa is given.
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| 2. |
- Gastineau, R., et al.
(författare)
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Haslea ostrearia-like Diatoms: Biodiversity out of the Blue
- 2014
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Ingår i: Advances in Botanical Research. - London : Academic Press Ltd-Elsevier Science Ltd. - 0065-2296. ; 71, s. 441-465
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Tidskriftsartikel (refereegranskat)abstract
- Diatoms are usually referred to as golden-brown microalgae, due to the colour of their plastids and to their pigment composition, mainly carotenoids (fucoxanthin, diadinoxanthin, diatoxanthin), which mask chlorophylls a and c. The species Haslea ostrearia Gaillon/Bory (Simonsen) appears unique because of its extraplastidial bluish colour, a consequence of the presence of a water-soluble blue pigment at cell apices, marennine. When released in seawater, marenbine can be fixed on gills of oysters and other bivalves, which turn green. This greening phenomenon is economically exploited in Southwestern France, as it gives an added value to oysters. For decades, this singularity ascribed a worldwide distribution to H. ostrearia, first as Vibrio ostrearius, then Navicula ostrearia, last as H. ostrearia, when the genus Haslea was proposed by R. Simonsen (1974). Indeed, this 'birthmark' (presence of blue apices) made H. ostrearia easily recognisable without further scrutiny and identification of the microalga as well as its presence easily deduced from the greening of bivalves. Consequently, the widely admitted cosmopolitan character of H. ostrearia has only been questioned recently, following the discovery in 2008, of a new species of blue diatom in the Black Sea, Haslea karadagensis. The biodiversity of blue diatoms suddenly increased with the finding of other blue species in the Mediterranean Sea, the Canary Islands, etc., the taxonomic characterization of which is in progress. This review thus focuses on the unsuspected biodiversity of blue diatoms within the genus Haslea. Methods for species determination (morphometrics, chemotaxonomy, genomics), as well as a new species, are presented and discussed.
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| 3. |
- Gastineau, R, et al.
(författare)
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Inheritance of Mitochondrial DNA in the Pennate Diatom Haslea ostrearia (Naviculaceae) during Auxosporulation Suggests a Uniparental Transmission
- 2013
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Ingår i: Protist. - 1434-4610 .- 1618-0941. ; 164:3, s. 340-351
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Tidskriftsartikel (refereegranskat)abstract
- We present the first study examining mtDNA transmission in diatoms, using sexual progeny of the pennate species Has lea ostrearia (Naviculaceae). A fragment of the cytochrome oxidase subunit I gene (cox1) with 7 nucleic substitutions between parental clones was used as a parental tracer in 16 F1 clones obtained from two pairs of mating crosses. Each cross involved a parental clone isolated from France (Bay of Bourgneuf) and Sweden (Kattegat Bay). We determined that all progeny possessed only one cox1 parental haplotype. These results suggest that the mitochondrial DNA transmission in H. ostrearia is uniparental. Implications and new topics of investigation are discussed. (C) 2013 Elsevier GmbH. All rights reserved.
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| 4. |
- Granfors, Anna, 1978, et al.
(författare)
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Biogenic halocarbons in young Arctic sea ice and frost flowers
- 2013
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 155, s. 124-134
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Tidskriftsartikel (refereegranskat)abstract
- The fate of halocarbons, naturally produced volatile halogenated organic compounds, in young Arctic sea ice was studied to better understand the role of sea ice in halocarbon cycling. In early spring, halocarbons were measured in sea ice frozen in core holes, during 12 days of formation and freezing. In order to understand which factors govern halocarbon concentration and distribution, salinity, temperature and biological parameters were monitored in the growing sea ice. It was found that sea ice participates in the cycling of halocarbons between sea and air. Sea ice concentrations and distributions of these compounds were influenced by production in the ice, where ice-inhabiting microorganisms caused local increases in halocarbon concentrations. Moreover, the halocarbon ice concentration decrease/change with time did not follow ice salinity, suggesting that additional removal processes caused sea ice to be a source of halogens to overlying air. The net production rate of bromoform in the surface of newly frozen ice was estimated to 14 pmol L−1 d−1 and the maximum removal rate was 18 pmol L−1 d−1. In addition frost flowers on newly formed sea ice were identified as contributors of halocarbons to the atmosphere with halocarbon concentrations in the same order of magnitude as in sea ice brine
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| 5. |
- Karlberg, Maria, et al.
(författare)
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Impact of temperature and species interaction on filamentous cyanobacteria may be more important than salinity and increased pCO(2) levels
- 2013
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 160:8, s. 2063-2072
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Tidskriftsartikel (refereegranskat)abstract
- A future business-as-usual scenario (A1FI) was tested on two bloom-forming cyanobacteria of the Baltic Proper, Nodularia spumigena and Aphanizomenon sp., growing separately and together. The projected scenario was tested in two laboratory experiments where (a) interactive effects of increased temperature and decreased salinity and (b) interactive effects of increased temperature and elevated levels of pCO(2) were tested. Increased temperature, from 12 to 16 A degrees C, had a positive effect on the biovolume and photosynthetic activity (F (v)/F (m)) of both species. Compared when growing separately, the biovolume of each species was lower when grown together. Decreased salinity, from 7 to 4, and elevated levels of pCO(2), from 380 to 960 ppm, had no effect on the biovolume, but on F (v)/F (m) of N. spumigena with higher F (v)/F (m) in salinity 7. Our results suggest that the projected A1FI scenario might be beneficial for the two species dominating the extensive summer blooms in the Baltic Proper. However, our results further stress the importance of studying interactions between species.
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| 6. |
- Ligowski, R., et al.
(författare)
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Rhoicosphenia michali: a new species of marine diatom (Bacillariophyta) from King George Island, Antarctica
- 2014
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Ingår i: Phytotaxa. - : Magnolia Press. - 1179-3155 .- 1179-3163. ; 191:1, s. 141-153
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Tidskriftsartikel (refereegranskat)abstract
- Rhoicosphenia michali sp. nov., described from the shallow sublittoral zone in Antarctica, is the second species in the genus with just one raphe slit on its convex valve. The first species, Rhoicosphenia flexa, was also described from marine coastal habitats in the Southern Hemisphere. Here, the morphology and ecology of R. flexa and R. michali are compared. The new species described herein may be endemic to Antarctica and can be found as free living cells on the shallow seabed, although it mainly occurs on the red alga Georgiella confluens, which is endemic to Antarctica.
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| 7. |
- Mohlin, Malin, 1966, et al.
(författare)
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Interspecific Resource Competition-Combined Effects of Radiation and Nutrient Limitation on Two Diazotrophic Filamentous Cyanobacteria
- 2012
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 63:4, s. 736-750
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Tidskriftsartikel (refereegranskat)abstract
- The cyanobacterial blooms in the Baltic Sea are dominated by diazotrophic cyanobacteria, the potentially toxic species Aphanizomenon sp. and the toxic species Nodularia spumigena. The seasonal succession with peaks of Aphanizomenon sp., followed by peaks of N. spumigena, has been explained by the species-specific niches of the two species. In a three-factorial outdoor experiment, we tested if nutrient and radiation conditions may impact physiological and biochemical responses of N. spumigena and Aphanizomenon sp. in the presence or absence of the other species. The two nutrient treatments were f/2 medium without NO (3) (-) (-N) and f/2 medium without PO (4) (3-) (-P), and the two ambient radiation treatments were photosynthetic active radiation > 395 nm (PAR) and PAR + UV-A + UV-B > 295 nm. The study showed that Aphanizomenon sp. was not negatively affected by the presence of N. spumigena and that N. spumigena was better adapted to both N and P limitation in interaction with ultraviolet radiation (UVR, 280-400 nm). In the Baltic Sea, these physical conditions are likely to prevail in the surface water during summer. Interestingly, the specific growth rate of N. spumigena was stimulated by the presence of Aphanizomenon sp. We suggest that the seasonal succession, with peaks of Aphanizomenon sp. followed by peaks of N. spumigena, is a result from species-specific preferences of environmental conditions and/or stimulation by Aphanizomenon sp. rather than an allelopathic effect of N. spumigena. The results from our study, together with a predicted stronger stratification due to effects of climate change in the Baltic Sea with increased temperature and increased precipitation and increased UV-B due to ozone losses, reflect a scenario with a continuing future dominance of the toxic N. spumigena.
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| 8. |
- Pattanaik, Bagmi, 1977, et al.
(författare)
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Production of the cyanotoxin nodularin-A multifactorial approach
- 2010
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Ingår i: Harmful Algae. - : Elsevier BV. - 1568-9883. ; 10:1, s. 30-38
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Tidskriftsartikel (refereegranskat)abstract
- Summer blooms in the Baltic Sea are dominated by the diazotrophic cyanobacteria Nodularia spumigena and Aphanizomenon sp. During the blooms, N. spumigena is concentrated to the water surface and exposed to high irradiances of both photosynthetic active radiation (PAR, 400-700 nm) and ultraviolet radiation (UVR, 280-400 nm), in addition, this organism is exposed to seasonal changes in nutrient conditions. N. spumigena produces nodularin, a hepatotoxin lethal to wild and domestic animals. It has been suggested that the accumulation of nodularin within the cell and the release from the cell are affected by different environmental factors. One laboratory experiment and two outdoor experiments were performed to investigate the interaction of two radiation treatments, PAR and PAR + UV-A + UV-B (PAB); three nutrient treatments, nutrient replete (NP), nitrogen limited (-N), and phosphorus limited (-P) and the presence and absence of Aphanizomenon sp. on intracellular as well as extracellular nodularin concentration in N. spumigena. In this study, we hypothesised that the interaction of ambient radiation, nutrient limitation, and the presence or absence of Aphanizomenon sp. would affect the accumulation and release of nodularin. We further hypothesised that the presence of Aphanizomenon sp. would increase the production and release of nodularin and that this increase would have a negative effect on the specific growth rate of this co-existing species. Significant interaction effects were found between the factors investigated. In all three experiments, the lowest intracellular nodularin concentrations were found under phosphorus limitation. The highest intra- and extracellular nodularin concentrations were observed under nitrogen limitation when shielded from UVR. In our opinion, further increase of nitrogen removal in e.g. sewage treatment, should consider a possible increased toxicity of the N. spumigena blooms. The presence of N. spumigena had no significant effect on the specific growth rate of Aphanizomenon sp. under different radiation and nutrient treatments. Thus, we conclude that although nodularin accumulation and release were dependent on different environmental conditions, it did not affect the co-existing species Aphanizomenon sp. (C) 2010 Elsevier B.V. All rights reserved.
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| 9. |
- Roleda, Michael Y., et al.
(författare)
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UVR defense mechanisms in eurytopic and invasive Gracilaria vermiculophylla (Gracilariales, Rhodophyta)
- 2012
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 146:2, s. 205-216
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Tidskriftsartikel (refereegranskat)abstract
- The invasive success of Gracilaria vermiculophylla has been attributed to its wide tolerance range to different abiotic factors, but its response to ultraviolet radiation (UVR) is yet to be investigated. In the laboratory, carpospores and vegetative thalli of an Atlantic population were exposed to different radiation treatments consisting of high PAR (photosynthetically active radiation) only (P), PAR+UV-A (PA) and PAR+UV-A+UV-B (PAB). Photosynthesis of carpospores was photoinhibited under different radiation treatments but photosystem II (PSII) function was restored after 12 h under dim white light. Growth of vegetative thalli was significantly higher under radiation supplemented with UVR. Decrease in chlorophyll a (Chl a) under daily continuous 16-h exposure to 300 mu mol photons m-2 s-1 of PAR suggests preventive accumulation of excited chlorophyll molecules within the antennae to minimize the generation of dangerous reactive oxygen species. Moreover, an increase in total carotenoids and xanthophyll cycle pigments (i.e. violaxanthin, antheraxanthin and zeaxanthin) further suggests effective photoprotection under UVR. The presence of the ketocarotenoid beta-cryptoxanthin also indicates protection against UVR and oxidative stress. The initial concentration of total mycosporine-like amino acids (MAAs) in freshly-released spores increased approximately four times after 8-h laboratory radiation treatments. On the other hand, initial specific MAAs in vegetative thalli changed in composition after 7-day exposure to laboratory radiation conditions without affecting the total concentration. The above responses suggest that G. vermiculophylla have multiple UVR defense mechanisms to cope with the dynamic variation in light quantity and quality encountered in its habitat. Beside being eurytopic, the UVR photoprotective mechanisms likely contribute to the current invasive success of the species in shallow lagoons and estuaries exposed to high solar radiation.
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| 10. |
- Steinhoff, Franciska S., et al.
(författare)
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Cyanobacteria in Scandinavian coastal waters - A potential source for biofuels and fatty acids?
- 2014
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 5, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- Since land-based biofuel production competes with conventional food production, a water-based biomass and biofuel production from cyanobacteria offers large potential. This study investigates the application potential of cyanobacteria for fuel production and by-products by mimicking nutrient depleted environmental conditions. Three Baltic cyanobacteria strains (Aphanizomenon flos-aquae, Dolichospermum lemmermannii and Nodularia spumigena) were inoculated in full nutrient levels, as well as phosphorus and nitrogen depleted medium, before being monitored for 14 days. For screening reasons, multiple parameters such as fatty acids, photosynthetic pigments including phycobilins, biovolume, photosynthetic activity, inorganic nutrients, particulate organic carbon, nitrogen and phosphorous were investigated every seven days. We observed a strong negative relationship between lipid content, growth and nutrient availability, resulting in high lipid and pigment production in combination with a limited growth rate in nutrient depleted treatments. Our results suggest that cultivation and harvest of bloom-forming cyanobacteria for fuel and by-product production are feasible in Scandinavia, but strongly depends on the desired compounds and biomass. Each cyanobacteria species originally has a species-specific chemical fingerprint that may be modified by rearing conditions and harvesting period to meet the needs of the consumer. This leads to important conclusions regarding future culturing conditions and biomass production of the desired compounds.
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