| 1. |
- Annenkova, Nataliia V., et al.
(författare)
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Closely related dinoflagellate species in vastly different habitats–an example of a marine–freshwater transition
- 2020
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Ingår i: European Journal of Phycology. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 55:4, s. 478-489
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Tidskriftsartikel (refereegranskat)abstract
- Phytoplankton are present in a large variety of aquatic environments, ranging from small freshwater ponds to the oceans. Typically, freshwater and marine species are not closely related, indicating an ancient divergence and that salinity poses a strong dispersal barrier. Here we reveal a common recent origin of two dinoflagellates that are well adapted to different habitats. Gymnodinium baicalense inhabits the geologically old freshwater Lake Baikal, which is located in the middle of the Eurasian continent. Gymnodinium corollarium, on the other hand, is a brackish water species from the Baltic Sea. Both species form blooms under ice during the spring. We generated 10 DNA sequences from these species. The partial 28S rRNA gene from G. baicalense and the partial 18S rRNA gene and internal transcribed spacer-2 (ITS2) from G. corollarium were sequenced for the first time. A more detailed description of G. baicalense, which was previously known only from light microscopy observations, is also provided. In the laboratory we demonstrated that G. baicalense is strictly adapted to fresh water, while G. corollarium had a wide salinity tolerance. However, the two species have almost identical morphology, identical SSU rRNA gene sequences, and only small differences in the LSU rRNA gene and ITS2. We infer a common ancestor, which was a species from the Arctic region with a tolerance to a range of salinities. Our data support the scenario that the under-ice phytoplankton community in Lake Baikal has been formed recently, even though the lake is the oldest in the world.
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| 2. |
- Díaz, Patricio A., et al.
(författare)
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Species diversity and abundance of dinoflagellate resting cysts seven months after a bloom of Alexandrium catenella in two contrasting coastal systems of the Chilean Inland Sea
- 2018
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Ingår i: European Journal of Phycology. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 53:3, s. 410-421
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Tidskriftsartikel (refereegranskat)abstract
- In Chile, 90% of the fish farms and major natural shellfish beds are located in the region surrounding the Inland Sea, where over the last few decades harmful phytoplankton blooms have often been observed. The onset and recurrence of bloom events are often related to the resuspension and germination of resting cysts that have accumulated in the sediments. The degree of cyst settling, accumulation and germination is highly variable between areas and depends on physical and environmental factors. To learn how differences in oceanographic exposure, amount of river runoff and bathymetry affect dinoflagellate cyst deposition, we examined the diversity and abundance of dinoflagellate resting cysts from two hydrographically contrasting coastal areas (oceanic Guaitecas Archipelago and estuarine Pitipalena Fjord) of the Chilean Inland Sea in September 2006, seven months after a bloom of Alexandrium catenella, a producer of paralytic shellfish toxin. Cyst species diversity consisted of 18 taxa, including A. catenella and the noxious species Protoceratium reticulatum, both of which have caused blooms in the study area. Our results revealed significant differences between the two study sites in terms of the abundance and diversity of resting cysts, suggesting that in the specific case of A. catenella, only Guaitecas stations have potential for cyst accumulation and successful growth of cells. However, there was no evidence of long-term resting cyst beds of A. catenella at either study site.
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| 3. |
- Engelen, Aschwin H., et al.
(författare)
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Effects of wave exposure and depth on biomass, density and fertility of the fucoid seaweed Sargassum polyceratium (Phaeophyta, Sargassaceae)
- 2005
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Ingår i: EUROPEAN JOURNAL OF PHYCOLOGY. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 40:2, s. 149-158
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Tidskriftsartikel (refereegranskat)abstract
- Sargassum polyceratium is widely distributed around the island of Curac¸ao (Netherlands Antilles) where it inhabits strongly contrasting habitats. Changes in population structure have been followed in three bays with increasing levels of wave exposure at two depths: shallow (0 m) and deep (18 m). The effects of increasing wave exposure were investigated by studying three deepwater populations; and the effects of depth by studying shallow- and deep-water populations in the two calmer bays. Total density and stage density (reproductive thalli, juvenile thalli) were determined and total and individual thallus biomass was estimated non-destructively. In the most wave-exposed deep-water population thalli were twice as long with more than twice the biomass than in the calmest deep-water population. Total density and juvenile density were highest in the bay with intermediate wave exposure. Depth was an important factor at both the individual and population level. Shallow-water thalli had basal holdfast areas that were four times larger than those from deep water, and thallus biomass was positively correlated with holdfast area. Shallow-water juveniles invested more in the development of a holdfast and lateral growth than deep-water juveniles. Total biomass per quadrat was up to 10-fold higher in shallow- than in deep-water populations. In shallow-water populations reproductive thalli were present throughout the year whereas in deep-water populations they were present only during autumn and winter. We conclude that both wave exposure and depth affect population structure. Thalli were generally bigger and total biomass higher in the more exposed bay(s) and in shallower water, contradicting the general pattern in macroalgae of reduced size and biomass with increasing wave exposure.
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| 4. |
- Gylle, Maria, et al.
(författare)
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Fluorescence Emission Spectra of Marine and Brackish Water Ecotypes of Fucus vesiculosus L. and F. radicans sp. Nov. (Phaeophyceae) Reveal Differences in Light Harvesting Apparatus.
- 2011
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Ingår i: European journal of phycology. - : John Wiley & Sons. - 0967-0262 .- 1469-4433 .- 0022-3646. ; 47:1, s. 98-105
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Tidskriftsartikel (refereegranskat)abstract
- The Bothnian Sea in the northerly part of the Baltic Sea is a geologically recent brackish-water environment, and rapid speciation is occurring in the algal community of the Bothnian Sea. We measured low-temperature fluorescence emission spectra from the Bothnian Sea and the Norwegian Sea ecotypes of Fucus vesiculosus L., a marine macroalga widespread in the Bothnian Sea. Powdered, frozen thallus was used to obtain undistorted emission spectra. The spectra were compared with spectra measured from the newly identified species Fucus radicans L.Bergström et L. Kautsky, which is a close relative of F. vesiculosusand endemic to the Bothnian Sea. The spectrum of variable fluorescence was used to identify fluorescence peaks originating in PSI and PSII in this chl c–containing alga. The spectra revealed much higher PSII emission, compared to PSI emission, in the Bothnian Sea ecotype of F. vesiculosus than in F. radicans or in the Norwegian Sea ecotype of F. vesiculosus. The results suggest that more lightharvesting chl a ⁄ c proteins serve PSII in the Bothnian Sea ecotype of F. vesiculosusthan in the two other algal strains. Treatment of the Bothnian Sea ecotype of F. vesiculosusin high salinity (10, 20, and 35 practical salinity units) for 1 week did not lead to spectral changes, indicating that the measured features of the Bothnian Sea F. vesiculosus are stable and not simply a direct result of exposure to low salinity.
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| 5. |
- Huseby, Siv, et al.
(författare)
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Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatom Chaetoceros socialis
- 2012
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Ingår i: European journal of phycology. - : Taylor & Francis. - 0967-0262 .- 1469-4433. ; 47:4, s. 480-489
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Tidskriftsartikel (refereegranskat)abstract
- Morphology and molecular phylogeny constitute the structural elements of diatom taxonomy. These approaches do not, however, give information on the functioning of taxa. Additional methods to serve a more integrated and wide-ranging taxonomy have therefore been called for. Metabolic fingerprinting is one approach used within the field of metabolomics, often applied in classification of samples. Here we apply metabolic fingerprinting in a taxonomic study of a cryptic diatom species. Strains of the cosmopolitan diatom Chaetoceros socialis from two geographical areas; the north-east Atlantic and Arctic and the Gulf of Naples, were cultivated at three different temperatures; 2.5, 8 and 13°C. The strains from the two different geographical areas exhibited different growth rates as well as different photosynthetic efficiencies. Algal extracts, collected at the end of the growth experiments, were analysed by Ultra-Performance Liquid Chromatography High Resolution Mass Spectrometry. The two groups of strains were separated by principal component analysis of their metabolic fingerprints. Analysis of the data revealed both qualitative and quantitative differences in metabolite markers. These phenotypic differences reinforce differences also found for morphology, phylogenetic markers and growth rates, and point at different adaptive characteristics in organisms living under different temperature regimes.
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| 6. |
- Isaeus, M., et al.
(författare)
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Effects of filamentous algae and sediment on recruitment and survival of Fucus serratus (Phaeophyceae) juveniles in the eutrophic Baltic Sea
- 2004
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Ingår i: European journal of phycology. - 0967-0262 .- 1469-4433. ; 39:3, s. 301-307
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication of the Baltic Sea has increased both the growth of annual filamentous algae and the rate of sedimentation. Together these factors may have a detrimental effect on the survival of perennial macroalgal populations. The aim of this research was to study how these factors affect the colonization success of Fucus serratus at the local level. We investigated the settlement and survival of F. serratus germlings through a combination of field studies and laboratory experiments. The study area lay off the east coast of Oland, along the central Baltic Sea, where consistently-submerged, extensive fucoid stands occur at depths of 2- 10 in, together with turf-forming filamentous algae, mainly Polysiphonia fucoides. Very few F. serratus juveniles were observed outside the sweeping radius of adult F. serratus individuals at a 7-m depth, while abundant recruits were found inside F. serratus stands. Amounts of filamentous algae and sediment were significantly larger outside the F. serratus stands than inside, and the amount of fine sediment (< 0.25 mm) was positively correlated with the amount of filamentous algae, suggesting that fine sediment accumulates in the turf. Experimental studies showed that both filamentous algae and sediment negatively affect the settlement ability of F. serratus eggs and zygotes and the subsequent survival of the germlings, with sediment having the strongest effect. Thus, the prior existence of an adult F. serratus population may allow for continuing recruitment of juveniles, while colonization of new areas unaffected by the sweeping effect of larger individuals seems very difficult under current conditions.
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| 7. |
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| 8. |
- Kolzenburg, Regina, et al.
(författare)
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Physiological characterisation of the calcified alga Corallina officinalis (Rhodophyta) from the leading to trailing edge in the Northeast Atlantic
- 2023
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Ingår i: European journal of phycology. - : Taylor & Francis. - 0967-0262 .- 1469-4433. ; 58:1, s. 83-98
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Tidskriftsartikel (refereegranskat)abstract
- Intertidal macroalgae are exposed to many biotic and abiotic stressors, including significant fluctuations in environmental parameters such as salinity, temperature, pH and solar radiation. This study characterized populations of the intertidal calcifying red alga Corallina officinalis across its geographic distribution in the North-east Atlantic. Processes examined included primary production, respiration, light and dark calcification, photosynthesis-irradiance, and calcification-irradiance evolution. Results confirmed significant differences in the physiology of C. officinalis between latitudes with a clear north-to-south gradient. Compared with central and southern populations of this species, northern populations appeared to be the most robust, showing potential for local physiological adaptation in response to increased variability in environmental factors present within their habitat. Conversely, southern populations displayed a distinct lack of local adaptation compared with northern populations. This is possibly due to southern populations being located within an environment at the upper limit of their stress tolerance, therefore restricting the species’ ability to adapt. As a result, future permanent decline, or even disappearance, of C. officinalis within southern locations of the North-east Atlantic could occur, a process that is likely to be accelerated by predicted future climatic changes. Furthermore, given the essential role these ecosystem engineers play within their habitat, any loss of C. officinalis is also expected to have a strongly negative impact on the surrounding environment.
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| 9. |
- Lage, Sandra, et al.
(författare)
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Kinetics of beta-N-methylamino-L-alanine (BMAA) and 2, 4-diaminobutyric acid (DAB) production by diatoms: the effect of nitrogen
- 2019
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Ingår i: European Journal of Phycology. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 54:1, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- The neurotoxins beta-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB) are produced by cyanobacteria, diatoms and dinoflagellates and have been detected in seafood worldwide. Our present knowledge of their metabolism or biosynthesis is limited. In this study, the production of BMAA and DAB as a function of time was monitored in five strains representing four species of diatoms, i.e. Phaeodactylum tricornutum, Thalassiosira weissflogii, Thalassiosira pseudonana and Navicula pelliculosa, previously identified as BMAA and DAB producers. Subsequently, three strains were selected and exposed to three nitrogen treatments - starvation, control (the standard concentration in f/2 medium) and enrichment, because BMAA metabolism has been suggested to be closely associated with cellular nitrogen metabolism in both cyanobacteria and diatoms. Chlorophyll a and total protein concentrations were also determined. Our results indicate that BMAA and DAB production in diatoms is species- and strain-specific. However, production might also be affected by stress, particularly as related to nitrogen starvation and cell density. Furthermore, this study shows a significant correlation between the production of the two neurotoxins which might further suggest common steps in the metabolic pathways.
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| 10. |
- Leblond, J D, et al.
(författare)
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Fatty acid and sterol composition of two evolutionarily closely related dinoflagellate morphospecies from cold Scandinavian brackish and freshwaters
- 2006
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Ingår i: European Journal of Phycology. - : Informa UK Limited. - 1469-4433 .- 0967-0262. ; 41:3, s. 303-311
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the lipid composition of cold-adapted dinoflagellates. Here, we investigate Peridinium aciculiferum and Scrippsiella hangoei, two cold-adapted dinoflagellate morphospecies that present significant differences in general morphology, physiology and habitat, but which share identical ribosomal DNA (rDNA) sequences, indicating a recent evolutionary divergence between them. Despite their present taxonomic names, it is now known that these two genetically isolated morphospecies are evolutionarily related to the so-called Pfiesteria-like species. We have found that chloroplast-associated glycolipids from P. aciculiferum and S. hangoei contained a higher relative percentage of two polyunsaturated C-18 fatty acids (octadecapentaenoic [18:5(n-3)] and octadecatetraenoic [18:4(n-3)] acids), and a lower relative percentage of hexadecanoic acid (16:0) than typically observed in previously examined warm-adapted dinoflagellate species. This suggests that these two fatty acids provided the requisite membrane fluidity for chloroplasts under a cold growth condition in these two organisms. A similar increase in 18:5(n-3) and 18:4(n-3) over warm-adapted species was also found in the phospholipids and triglycerides. P. aciculiferum and S. hangoei were also examined for the production of unique sterols that may serve as chemical biomarkers. Both were found to have a very similar sterol composition, consisting of two common dinoflagellate sterols, cholestanol and dinostanol, as dominant sterols, along with a number of other common dinoflagellate sterols as minor sterols. This demonstrated the absence of a specific steroidal biomarker but, more importantly, showed that these two morphospecies still produce very similar sterols despite having diverged in several other traits.
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