scholarly journals Linking extreme seasonality and gene expression in arctic marine protists

2021 ◽  
Author(s):  
Magdalena Wutkowska ◽  
Anna Vader ◽  
Ramiro Logares ◽  
Eric Pelletier ◽  
Tove M. Gabrielsen
Keyword(s):  
Gene Expression ◽  
Light Availability ◽  
High Arctic ◽  
Polar Night ◽  
Microbial Eukaryotes ◽  
Seasonal Impact ◽  
Polar Day ◽  
Arctic Fjord ◽  
Marine Protists ◽  
Extreme Seasonality

At high latitudes, strong seasonal differences in light availability affect marine organisms and restrict the timing of ecosystem processes. Marine protists are key players in Arctic aquatic ecosystems, yet little is known about their ecological roles over yearly cycles. This is especially true for the dark polar night period, which up until recently was assumed to be devoid of biological activity. A 12 million transcripts catalogue was built from 0.45-10 μm protist assemblages sampled over 13 months in a time series station in an arctic fjord in Svalbard. Community gene expression was correlated with seasonality, with light as the main driving factor. Transcript diversity and evenness were higher during polar night compared to polar day. Light-dependent functions had higher relative expression during polar day, except phototransduction. 64% of the most expressed genes could not be functionally annotated, yet up to 78% were identified in arctic samples from Tara Oceans, suggesting that arctic marine assemblages are distinct from those from other oceans. Our study increases understanding of the links between extreme seasonality and biological processes in pico- and nanoplanktonic protists. Our results set the ground for future monitoring studies investigating the seasonal impact of climate change on the communities of microbial eukaryotes in the High Arctic.

scholarly journals A marine zooplankton community vertically structured by light across diel to interannual timescales

2021 ◽  
Vol 17 (2) ◽  
pp. 20200810
Author(s):  
Laura Hobbs ◽  
Neil S. Banas ◽  
Jonathan H. Cohen ◽  
Finlo R. Cottier ◽  
Jørgen Berge ◽  
...  
Keyword(s):  
Predation Risk ◽  
Zooplankton Community ◽  
Foraging Strategy ◽  
High Arctic ◽  
Visual Predation ◽  
Marine Zooplankton ◽  
Arctic Fjord ◽  
Change Impact ◽  
Extreme Seasonality ◽  
The Vertical Distribution

The predation risk of many aquatic taxa is dominated by visually searching predators, commonly a function of ambient light. Several studies propose that changes in visual predation will become a major climate-change impact on polar marine ecosystems. The High Arctic experiences extreme seasonality in the light environment, from 24 h light to 24 h darkness, and therefore provides a natural laboratory for studying light and predation risk over diel to seasonal timescales. Here, we show that zooplankton (observed using acoustics) in an Arctic fjord position themselves vertically in relation to light. A single isolume (depth-varying line of constant light intensity, the value of which is set at the lower limit of photobehaviour reponses of Calanus spp. and krill) forms a ceiling on zooplankton distribution. The vertical distribution is structured by light across timescales, from the deepening of zooplankton populations at midday as the sun rises in spring, to the depth to which zooplankton ascend to feed during diel vertical migration. These results suggest that zooplankton might already follow a foraging strategy that will keep visual predation risk roughly constant under changing light conditions, such as those caused by the reduction of sea ice, but likely with energetic costs such as lost feeding opportunities as a result of altered habitat use.

scholarly journals Strong Seasonality of Marine Microbial Eukaryotes in a High-Arctic Fjord (Isfjorden, in West Spitsbergen, Norway)

2016 ◽  
Vol 82 (6) ◽  
pp. 1868-1880 ◽  
Author(s):  
Miriam Marquardt ◽  
Anna Vader ◽  
Eike I. Stübner ◽  
Marit Reigstad ◽  
Tove M. Gabrielsen
Keyword(s):  
454 Sequencing ◽  
High Arctic ◽  
Early Spring ◽  
Small Cells ◽  
The Arctic ◽  
Content Type ◽  
Dna And Rna ◽  
Microbial Eukaryotes ◽  
West Spitsbergen ◽  
Extreme Seasonality

ABSTRACTThe Adventfjorden time series station (IsA) in Isfjorden, West Spitsbergen, Norway, was sampled frequently from December 2011 to December 2012. The community composition of microbial eukaryotes (size, 0.45 to 10 μm) from a depth of 25 m was determined using 454 sequencing of the 18S V4 region amplified from both DNA and RNA. The compositional changes throughout the year were assessed in relation toin situfjord environmental conditions. Size fractionation analyses of chlorophyllashowed that the photosynthetic biomass was dominated by small cells (<10 μm) most of the year but that larger cells dominated during the spring and summer. The winter and early-spring communities were more diverse than the spring and summer/autumn communities. Dinophyceae were predominant throughout the year. The ArcticMicromonasecotype was abundant mostly in the early-bloom and fall periods, whereas heterotrophs, such as marine stramenopiles (MASTs), Picozoa, and the parasitoid marine alveolates (MALVs), displayed higher relative abundance in the winter than in other seasons. Our results emphasize the extreme seasonality of Arctic microbial eukaryotic communities driven by the light regime and nutrient availability but point to the necessity of a thorough knowledge of hydrography for full understanding of their succession and variability.

scholarly journals Modeling studies of the bioluminescence potential dynamics in a high Arctic fjord during polar night

2021 ◽  
Author(s):  
Igor Shulman ◽  
Jonathan H. Cohen ◽  
Mark A. Moline ◽  
Stephanie Anderson ◽  
E. Joseph Metzger ◽  
...  
Keyword(s):  
High Arctic ◽  
Shelf Break ◽  
Polar Night ◽  
Modeling Approach ◽  
Modeling Studies ◽  
Shelf Slope ◽  
Arctic Fjord

AbstractDuring polar nights in January 2012 and 2017, significantly higher bioluminescence (BL) potential emissions in the upper 50 m were observed in the fjord Rijpfjorden (Svalbard, Norway) in comparison to offshore stations (located on the shelf-break, shelf-slope areas and in the deeper water). The objective of this paper is to better understand why, during two polar nights (separated by 5 years), the values of BL potential in the northern Svalbard fjord are higher than at offshore stations, and what the role of advection is in observed elevated BL potential values in the top 50 m of the fjord. To address the above objective, we applied the same BL potential modeling approach and strategies during polar nights for both 2012 and 2017. For both years, advection of BL potential from offshore (including upwelling along the shelf, shelf-slope) produced an increase of BL potential in the fjord area, in spite of the introduction of mortality in bioluminescent organisms. Observations of BL potential indicated high emissions at depths below 100 m at offshore stations for both polar nights. Our modeling studies demonstrated that these high values of BL potential below 100 m are upwelled and advected to the top 50 m of the fjord. We demonstrated that upwelling and advection of these deep high BL potential values (and therefore, upwelling and advection of corresponding bioluminescent taxa) from offshore areas are dominant factors in observed BL potential dynamics in the top 50 m in the fjord.

Proton-pumping rhodopsins are abundantly expressed by microbial eukaryotes in a high-Arctic fjord

2018 ◽  
Vol 20 (2) ◽  
pp. 890-902 ◽  
Author(s):  
Anna Vader ◽  
Haywood D. Laughinghouse ◽  
Colin Griffiths ◽  
Kjetill S. Jakobsen ◽  
Tove M. Gabrielsen
Keyword(s):  
High Arctic ◽  
Proton Pumping ◽  
Microbial Eukaryotes ◽  
Arctic Fjord

scholarly journals From polar night to midnight sun: Diel vertical migration, metabolism and biogeochemical role of zooplankton in a high Arctic fjord (Kongsfjorden, Svalbard)

2017 ◽  
Vol 62 (4) ◽  
pp. 1586-1605 ◽  
Author(s):  
G. Darnis ◽  
L. Hobbs ◽  
M. Geoffroy ◽  
J. C. Grenvald ◽  
P. E. Renaud ◽  
...  
Keyword(s):  
Vertical Migration ◽  
Diel Vertical Migration ◽  
High Arctic ◽  
Polar Night ◽  
Arctic Fjord

scholarly journals Using single-cell transcriptomics to understand functional states and interactions in microbial eukaryotes

2019 ◽  
Vol 374 (1786) ◽  
pp. 20190098 ◽  
Author(s):  
Chuan Ku ◽  
Arnau Sebé-Pedrós
Keyword(s):  
Gene Expression ◽  
Single Cell ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Interspecific Interactions ◽  
Single Cells ◽  
Life Cycles ◽  
Modern Biology ◽  
Microbial Eukaryotes ◽  
Eukaryotic Microorganisms

Understanding the diversity and evolution of eukaryotic microorganisms remains one of the major challenges of modern biology. In recent years, we have advanced in the discovery and phylogenetic placement of new eukaryotic species and lineages, which in turn completely transformed our view on the eukaryotic tree of life. But we remain ignorant of the life cycles, physiology and cellular states of most of these microbial eukaryotes, as well as of their interactions with other organisms. Here, we discuss how high-throughput genome-wide gene expression analysis of eukaryotic single cells can shed light on protist biology. First, we review different single-cell transcriptomics methodologies with particular focus on microbial eukaryote applications. Then, we discuss single-cell gene expression analysis of protists in culture and what can be learnt from these approaches. Finally, we envision the application of single-cell transcriptomics to protist communities to interrogate not only community components, but also the gene expression signatures of distinct cellular and physiological states, as well as the transcriptional dynamics of interspecific interactions. Overall, we argue that single-cell transcriptomics can significantly contribute to our understanding of the biology of microbial eukaryotes. This article is part of a discussion meeting issue ‘Single cell ecology’.

scholarly journals Glacial and depth influence on sublittoral macroalgal standing stock in a high-Arctic fjord

2020 ◽  
Vol 194 ◽  
pp. 104045
Author(s):  
Marta Ronowicz ◽  
Maria Włodarska-Kowalczuk ◽  
Piotr Kukliński
Keyword(s):  
Standing Stock ◽  
High Arctic ◽  
Arctic Fjord

Biochemical composition of particles shape particle-attached bacterial community structure in a high Arctic fjord

2019 ◽  
Vol 102 ◽  
pp. 581-592 ◽  
Author(s):  
Anand Jain ◽  
Kottekkatu Padinchati Krishnan ◽  
Archana Singh ◽  
Femi Anna Thomas ◽  
Nazira Begum ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Biochemical Composition ◽  
Bacterial Community Structure ◽  
High Arctic ◽  
Arctic Fjord

scholarly journals The littoral zone of polar lakes: inshore–offshore contrasts in an ice-covered High Arctic lake

2020 ◽  
pp. 1-24
Author(s):  
Paschale N. Bégin ◽  
Milla Rautio ◽  
Yukiko Tanabe ◽  
Masaki Uchida ◽  
Alexander I. Culley ◽  
...  
Keyword(s):  
Light Availability ◽  
Sharp Decrease ◽  
Open Water ◽  
High Arctic ◽  
Early Summer ◽  
Fatty Acid Profiles ◽  
Canadian High Arctic ◽  
Abrupt Increase ◽  
Horizontal Gradients

In ice-covered polar lakes, a narrow ice-free moat opens up in spring or early summer, and then persists at the edge of the lake until complete ice loss or refreezing. In this study, we analyzed the horizontal gradients in Ward Hunt Lake, located in the Canadian High Arctic, and addressed the hypothesis that the transition from its nearshore open-water moat to offshore ice-covered waters is marked by discontinuous shifts in limnological properties. Consistent with this hypothesis, we observed an abrupt increase in below-ice concentrations of chlorophyll a beyond the ice margin, along with a sharp decrease in temperature and light availability and pronounced changes in benthic algal pigments and fatty acids. There were higher concentrations of rotifers and lower concentrations of viruses at the ice-free sampling sites, and contrasts in zooplankton fatty acid profiles that implied a greater importance of benthic phototrophs in their inshore diet. The observed patterns underscore the structuring role of ice cover in polar lakes. These ecosystems do not conform to the traditional definitions of littoral versus pelagic zones but instead may have distinct moat, ice-margin, and ice-covered zones. This zonation is likely to weaken with ongoing climate change.

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