Sandra Gran Stadniczeñko

• Gran Stadniczeñko, Sandra; Krabberød, Anders Kristian; Sandaa, Ruth-Anne; Yau, Sheree; Egge, Elianne Dunthorn & Edvardsen, Bente (2019). Seasonal dynamics of algae-infecting viruses and their inferred interactions with protists. Viruses.  ISSN 1999-4915.  11(11), s 1- 16 . doi: 10.3390/v11111043 Fulltekst i vitenarkiv.
• Gran-Stadniczenko, Sandra; Egge, Elianne; Hostyeva, Vladyslava; Logares, Ramiro; Eikrem, Wenche & Edvardsen, Bente (2019). Protist Diversity and Seasonal Dynamics in Skagerrak Plankton Communities as Revealed by Metabarcoding and Microscopy. Journal of Eukaryotic Microbiology.  ISSN 1066-5234.  66(3), s 494- 513 . doi: 10.1111/jeu.12700 Fulltekst i vitenarkiv.
• Engesmo, Anette; Strand, David; Gran-Stadniczeñko, Sandra; Edvardsen, Bente; Medlin, Linda K. & Eikrem, Wenche (2018). Development of a qPCR assay to detect and quantify ichthyotoxic flagellates along the Norwegian coast, and the first Norwegian record of Fibrocapsa japonica (Raphidophyceae). Harmful Algae.  ISSN 1568-9883.  75, s 105- 117 . doi: 10.1016/j.hal.2018.04.007 Fulltekst i vitenarkiv. Vis sammendrag

  Blooms of ichthyotoxic microalgae pose a great challenge to the aquaculture industry world-wide, and there is a need for fast and specific methods for their detection and quantification in monitoring programs. In this study, quantitative real-time PCR (qPCR) assays for the detection and enumeration of three ichthyotoxic flagellates: the dinoflagellate Karenia mikimotoi (Miyake & Kominami ex Oda) Hansen & Moestrup and the two raphidophytes Heterosigma akashiwo (Hada) Hada ex Hara & Chihara and Fibrocapsa japonica Toriumi & Takano were developed. Further, a previously published qPCR assay for the dinoflagellate Karlodinium veneficum (Ballantine) Larsen was used. Monthly samples collected for three years (Aug 2009–Jun 2012) in outer Oslofjorden, Norway were analysed, and the results compared with light microscopy cell counts. The results indicate a higher sensitivity and a lower detection limit (down to 1 cell L−1) for both qPCR assays. Qualitative and semi-quantitative results were further compared with those obtained by environmental 454 high throughput sequencing (HTS, metabarcoding) and scanning electron microscopy (SEM) examination from the same samplings. All four species were detected by qPCR and HTS and/or SEM in outer Oslofjorden (Aug 2009–Jun 2012); Karlodinium veneficum was present year-round, whereas Karenia mikimotoi, Heterosigma akashiwo and Fibrocapsa japonica appeared mainly during the autumn in all three years. This is the first observation of Fibrocapsa japonica in Norwegian coastal waters. This species has previously been recorded off the Swedish west coast and German Bight, which may suggest a northward dispersal.

• Stadniczenko, Sandra Gran; Supraha, Luka; Egge, Elianne Dunthorn & Edvardsen, Bente (2017). Haptophyte Diversity and Vertical Distribution Explored by 18S and 28S Ribosomal RNA Gene Metabarcoding and Scanning Electron Microscopy. Journal of Eukaryotic Microbiology.  ISSN 1066-5234.  64(4), s 514- 532 . doi: 10.1111/jeu.12388 Fulltekst i vitenarkiv. Vis sammendrag

  Haptophyta encompasses more than 300 species of mostly marine pico‐ and nanoplanktonic flagellates. Our aims were to investigate the Oslofjorden haptophyte diversity and vertical distribution by metabarcoding, and to improve the approach to study haptophyte community composition, richness and proportional abundance by comparing two rRNA markers and scanning electron microscopy (SEM). Samples were collected in August 2013 at the Outer Oslofjorden, Norway. Total RNA/cDNA was amplified by haptophyte‐specific primers targeting the V4 region of the 18S, and the D1‐D2 region of the 28S rRNA. Taxonomy was assigned using curated haptophyte reference databases and phylogenetic analyses. Both marker genes showed Chrysochromulinaceae and Prymnesiaceae to be the families with highest number of Operational Taxonomic Units (OTUs), as well as proportional abundance. The 18S rRNA data set also contained OTUs assigned to eight supported and defined clades consisting of environmental sequences only, possibly representing novel lineages from family to class. We also recorded new species for the area. Comparing coccolithophores by SEM with metabarcoding shows a good correspondence with the 18S rRNA gene proportional abundances. Our results contribute to link morphological and molecular data and 28S to 18S rRNA gene sequences of haptophytes without cultured representatives, and to improve metabarcoding methodology.

• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten Foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2015). Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway. Marine Biology.  ISSN 0025-3162.  162(6), s 1215- 1226 . doi: 10.1007/s00227-015-2663-3

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• Edvardsen, Bente; Supraha, Luka; Gran-Stadniczeñko, Sandra; Eikrem, Wenche & John, Uwe (2020). An in-depth study of Chrysochromulina leadbeateri bloom in northern Norway during spring 2019. Vis sammendrag

  The toxic algal bloom of the haptophyte Chrysochromulina leadbeateri in spring 2019 was the largest bloom of this species in Norwegian waters and worldwide ever recorded. Starting in the Vestfjorden area in northern Norway during early May and expanding north to Balsfjorden and Tromsø area, the bloom caused a major mortality of farmed salmon, with over 13 000 tonns of fish reported as lost during the outbreak. The C. leadbeateri bloom in northern Norway was studied in-depth in frame of a research cruise led by Alfred Wegener Institute (Germany) and in collaboration with the University of Oslo. The cruise focused on studies of phytoplankton diversity, distribution and functional ecology in several fjord systems along the northern Norwegian coast (Lofoten-Vesterålen area, Balsfjorden, Lyngen, Porsangerfjorden, Laksefjorden, Tanafjorden). Biological and environmental data collected during the cruise allowed for detailed analyses of the blooming organism, its distribution patterns in northern Norway, and its ecology. Cultures of C. leadbeateri isolated from the bloom were used to determine the morphology, taxonomic identity, and phylogenetic placement of the organism, and to compare it with a C. leadbeateri strain isolated from the previous major bloom in 1991. Metabarcoding data, light microscopy counts and flow cytometry data were used to map the distribution and abundance of the species along the coast of northern Norway, and correlate its distribution with biotic and abiotic parameters. Preliminary results show that the blooming organism is genetically identical in marker genes to the strain from the bloom in Vestfjorden in 1991. However, both strains and C. leadbeateri in field material exhibit significant intraspecific genetic variability. Biogeographic mapping shows that the bloom was most pronounced in the Balsfjorden area, with maximum cell concentration of over 27 million cells L-1. From an ecological perspective, C. leadbeateri abundance showed positive correlation with phosphate and nitrate, negative correlation with salinity and a slightly positive correlation with temperature. The results of our work provide a unique, in-depth insight into C. leadbeateri blooms, which may help in the monitoring, modelling and predicting similar events in the future. Ongoing work in our group focus on physiological and genetic profiling of the isolated C. leadbeateri strains with the aim to improve our understanding of factors triggering toxicity and bloom formation.

• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2016). Are skeletal ossicles in echinoids unreliable chronometers? Reply to Russell and Narváez comment on “Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway” by Fagerli et al. 2015. Marine Biology.  ISSN 0025-3162.  163(7), s 160- 161 . doi: 10.1007/s00227-016-2928-5
• Edvardsen, Bente; Egge, Elianne Sirnæs; Stadniczenko, Sandra Gran; Johannessen, Torill Vik; Eikrem, Wenche; Sandaa, Ruth-Anne; Bittner, Lucie; de Vargas, Colomban; Larsen, Aud & Andersen, Tom (2015). Diversity and seasonal dynamics of marine haptophytes and their viruses and the role of biotic interactions. Vis sammendrag

  Members of the phytoplankton division Haptophyta are a major component in marine pico- and nanoplankton communities. They often occur in bloom concentrations that may have a major impact on the global carbon balance, on climate forcing and sometimes cause fish-kills. Because haptophytes are tiny and difficult to identify in the microscope little is known about their seasonal dynamics and ecological role at the species level. Virus may terminate haptophyte blooms and, according to the “killing the winner” concept, possibly prevent blooms by keeping them under constant control. The aim of this study within the HAPTODIV project was to reveal the diversity and dynamics of marine haptophytes to species level and how this relates to abiotic factors and viruses. We assessed the haptophyte and Phycodnaviridae/ Mimiviridae (algal viruses) taxonomic composition, OTU richness and relative abundance over time by high-throughput amplicon sequencing (metabarcoding) of monthly samples over 2 years from the outer Oslofjorden, Skagerrak, Southern Norway. Metabarcoding revealed higher haptophyte diversity (156 OTUs estimating species) than previously observed in the area with electron and light microscopy (85 spp), and most (84%) of this diversity remains to be cultured and sequenced. Many may represent novel lineages at the class to genus level, or species new for science. More than half of the OTUs (93) were affiliated with the order Prymnesiales such as members of e.g. Chrysochromulina and Prymnesium. Haptophyte richness and community composition showed high temporal variation and significant yearly periodicity correlating with light and temperature, with highest richness in autumn (Sep-Nov) and lowest in the spring (Apr-May). Our results indicated, however, that the abiotic factors only accounted for about 30% of the variation, and suggest that biotic factors explain some of the residual variation. Also algal virus diversity was high and showed temporal variations with highest richness in Sept-Oct. Biotic interactions between haptophytes and algal viruses were assessed by co-occurrence analyses. We detected 56 haptophyte-virus pairs with significant co-occurrence, of 49 000 possible pairs. The distribution patterns of these pairs may shed light on the role of virus infection on phytoplankton community composition and dynamics. We suggest that this approach may be a first step to test the “killing-the-winner” concept on haptophyte diversity and distribution.

• Edvardsen, Bente; Egge, Elianne Sirnæs; Stadniczenko, Sandra Gran; Johannessen, Torill Vik; Larsen, Aud; Sandaa, Ruth-Anne & Andersen, Tom (2015). Diversity, seasonal dynamics and biotic interactions in marine phytoplankton and virus communities. Vis sammendrag

  The taxonomic composition of phytoplankton communities and relative abundance of taxa in oceanic ecosystems undergo continuous change. This community reorganization is of major importance to higher trophic levels and biogeochemical cycles. This succession is partly accounted for by hydrographical and meteorological variations that select for different traits in time and space, but also by biological processes, such as pathogens. Virus may terminate haptophyte blooms and, according to the “killing the winner” concept, possibly prevent blooms by keeping them under constant control. We assessed the haptophyte (algal host) and Phycodnaviridae/Mimiviridae (virus) taxonomic composition and relative abundance by high-throughput amplicon sequencing of monthly samples over 2 years from the outer Oslofjorden. Haptophyte richness and community composition exhibited high temporal variation and significant yearly periodicity, with highest richness in autumn (Sept-Oct) and lowest in the spring (April-May). Also, algal virus diversity showed seasonal variations with highest richness in September-October and lowest in August. Biotic interactions between haptophytes and viruses and among haptophytes were evaluated to provide new insight in the role of biotic processes for phytoplankton community composition and dynamics.

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