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Species diversity of phototrophic eukaryotes (PEs) with cell size <3 µm in autumn phytoplankton of the Kara and Laptev seas was studied. High-throughput sequencing of the 18S rRNA gene V4 region ...revealed 15 classes of algae in the plankton pico-sized fraction, which belonged to five divisions:
Haptophyta
,
Cryptophyta
,
Chlorophyta
,
Ochrophyta
, and
Dinoflagellata. Dinoflagellata
and green algae of the class
Mamiellophyceae
were the main contributors to total PE sequences.
Chlorophyta
was the most diverse section, represented by seven classes:
Mamiellophyceae
,
Trebouxiophyceae
,
Nephroselmidophycea
,
Palmophyllophyceae
,
Pyramimonadophyceae
,
Chlorodendrophyceae
, and
Chlorophyceae
.
Bolidophyceaea
species
Triparma strigata
and
T. laevis
, as well as the diatom
Skeletonema marinoi
, were first identified in the Kara and Laptev Seas, respectively. The hydrological conditions on the stations determined the PE taxonomic composition. The diversity indices were higher at the stations located in the upper estuary of river Khatanga and at the areas of both seas adjacent to the Khatanga and Ob estuaries than at the northernmost Laptev Sea station. The obtained data showed that the taxonomic composition of the smallest phytoplankton fraction of the two shelf seas of the Russian Arctic was similar to that found in other Arctic regions.
The molecular diversity of poorly studied algae of Bolidophyceae class was first estimated by Illumina sequencing of V4 region of 18S rRNA gene in ice, under-ice water and summer water of the ...subarctic White Sea. We used two clustering thresholds–93 and 97%–and revealed 31 phylotypes of Bolidophyceae.
Triparma pacifica
and
Т. strigata
were identified to species level. The association of individual phylotypes to certain biotopes (ice or plankton) and stages of seasonal succession (under ice or summer plankton) has been established. Some phylotypes are found in different biotopes and over a wide temperature range. Due to changing their genetic composition, Bolidophyceae are a constant component of the photoautotrophic plankton and ice communities.
The White Sea is a unique marine environment combining features of temperate and Arctic seas. The composition and abundance of photosynthetic picoeukaryotes (PPEs) were investigated in the land-fast ...ice of the White Sea, Russia, in March 2013 and 2014. High-throughput tag sequencing (Illumina MiSeq system) of the V4 region of the 18S rRNA gene was used to reveal the diversity of PPE ice community. The integrated PPE abundance varied from 11 × 10⁶ cells/m² to 364 × 10⁶ cells/m²; the integrated biomass ranged from 0.02 to 0.26 mg C/m². The composition of seaice PPEs was represented by 16 algae genera belonging to eight classes and three super-groups. Chlorophyta, especially Mamiellophyceae, dominated among ice PPEs. The detailed analysis revealed the latent diversity of Micromonas and Mantoniella. Micromonas clade E2 revealed in the subarctic White Sea ice indicates that the area of distribution of this species is wider than previously thought. We suppose there exists a new Micromonas clade F. Micromonas clade C and Minutocellulus polymorphus were first discovered in the ice and extend the modern concept of sympagic communities’ diversity generally and highlights the importance of further targeting subarctic sea ice for microbial study.
Spring Picophytoplankton of the Kara Sea Belevich, T. A.; Milyutina, I. A.; Demidov, A. B. ...
Oceanology (Washington. 1965),
10/2022, Letnik:
62, Številka:
5
Journal Article
Recenzirano
The abundance, biomass, chlorophyll “a” concentration of picophytoplankton, contribution of picoalgae to total chlorophyll “a” and species composition of phototrophic picoeukaryotes (cells size less ...than 3 µm) were studied during 83 cruise of R/V
Akademik Mstislav Keldysh
in the Kara Sea in June 2021. The picophytoplankton abundance varied from 0.25 to 4.91 × 10
9
cell/m
3
, biomass–from 0.34 to 2.49 mg С/m
3
. The minimum abundance and biomass were found in the areas adjacent to the ice edge. The contribution of picophytoplankton to total chlorophyll a concentration in photic layer varied from 3 to 28% with maximum found in the stations free of ice more than 5 days. Picophytoplankton was represented by picoeukaryotes and cyanobacteria. The cyanobacteria contribution was low and varied from 0.2 to 1.8%. The Illumina sequencing of V4 region of 18S rRNA gene revealed that in the surface layer
Chaetoceros socialis
dominated in picoeukaryotes near ice edge during the diatom bloom. In the ice-free areas for more than 5 days small flagellates, such as
Micromonas polaris, Phaeocystis pouchetii
and
Pyramimonas diskoicola
, begin to develop in the surface layer after large phytoplankton descends to the lower horizon of upper mixed layer.
Picoalgae (defined as cells smaller than 2-3 μm) include members of diverse taxonomic groups. They are an important constituent of marine plankton and ice biota and play a significant ecological role ...in biogeochemical cycles. Despite their importance, the true extent of their diversity has only recently been uncovered by molecular surveys. The diversity of picoeukaryotes has not yet been studied in the White Sea, which is a unique marine environment combining features of temperate and Arctic seas. Here, we investigated the taxonomic composition of eukaryotic picoalgae in ice and under-ice water at a station located in the Kandalaksha Bay of the White Sea. We applied metagenomic survey using Illumina sequencing. Eight main algae phyla, namely, Chlorophyta, Katablepharidophyta, Haptophyta, Dinophyta, Cercozoa, Bacillariophyta, Cryptophyta, and Ochrophyta were identified. The genera
Paraphysomonas and Micromonas
and the order Pedinellales were most numerous in plankton; the genera
Paraphysomonas, Micromonas
, and
Metopion
were most abundant in ice. The number of “rare” phylotypes was 80 in under-ice water and 112 in ice. Some taxa of nanoand microalgae are identified for the first time in the White Sea phytoplankton. Our data provide a basis for further research of tiny phototrophs in the Russian Arctic.
The abundance, biomass, size structure of small photosynthetic flagellates (SPF; 3–10 µm), chlorophyll
a
(Chl
a
), and the contribution of SPF to the total phytoplankton biomass were studied in Onega ...Bay of the White Sea in September 2019. The Chl
a
concentration in the surface water layer of the bay varies from 0.36 to 0.83 mg/m
3
. The contribution of photosynthetic algae to the total phytoplankton biomass ranges from 79 to 83%. The abundance and biomass of SPF in the photic layer varies from 0.04 × 10
9
to 0.22 × 10
9
cells/m
3
and from 0.64 to 6.4 mg C/m
3
, respectively. Flagellates with a cell size of 6–10 µm dominate in the total SPF biomass and their share averages 82%. The SPF contribution to the total phytoplankton biomass in Onega Bay varies from 6 to 58% and does not depend on the phase of the tidal cycle. The obtained data on the SPF abundance evidenced that this group of protists plays a significant role in phytoplankton communities, and their estimate results in higher values of the total phytoplankton biomass of the White Sea in the fall compared to data obtained earlier.
Picophytoplankton abundance, biomass, and chlorophyll
a
concentration as well as contribution of picoalgae to total chlorophyll
a
, and species composition of phototrophic picoeukaryotes (cells size ...less than 3 µm) were studied in Blagopoluchia Bay (Novaya Zemlya archipelago) and the northwestern part of the Kara Sea in September 2017. In the Bay, the highest picophytoplankton abundance and biomass were found in the surface layer and averaged 0.75 × 10
9
cell/m
3
and 1.49 mg С/m
3
respectively. In the northwestern part of the Kara Sea, the highest abundance and biomass of picophytoplankton were observed in the 8 m layer and were 2.29 × 10
9
cells/m
3
and 2.76 mg С/m
3
respectively. The contribution of picophytoplankton to total chlorophyll
a
concentration varied from 12 to 24% in the Bay and reached 46% in the Kara Sea. The Illumina sequencing of the V4 region of 18S rRNA gene revealed eight classes of phototrophic picoeukaryotes. Mamiellophyceae dominated in the number of reads. Arctic endemic (
Micromonas polaris
) and widespread (
Bathycoccus prasinos
) species were revealed in both studied areas.
The spatial distribution of picophytoplankton abundance, biomass, chlorophyll
a
and the contribution of picoalgae to the total chlorophyll
a
was studied in the outer Ob River estuary with the ...adjacent shelf and in the western part of the Kara Sea. In August–September, the picophytoplankton abundance and biomass varied from 0.1 to 17.3 × 10
6
cell/L and from 0.06 to 9.20 mg С/m
3
, respectively. Photosynthetic picoeukaryotes dominated in the plankton picofraction; the contribution of cyanobacteria to the total picophytoplankton biomass did not exceed 11%. The highest contribution of picophytoplankton to the total phytoplankton abundance was observed at a lower (<11 mg/m
2
) euphotic zone integrated chlorophyll
a
. The spatial heterogeneity of picoforms contribution was determined by the silicon concentration.
Abundance and biomass of small photosynthetic flagellates (SPF; 3–10 µm), chlorophyll
a
concentration
,
and the contribution of SPF to total phytoplankton biomass at different stages of seasonal ...succession in ice and in surface water were studied in Kandalaksha Bay of the White Sea in September 2016 and February and July 2017. In summer, SPF biomass in the photic layer averaged 38.36 ± 9.77 mg C/m
3
, 2.22 ± 1.43 mg C/m
3
in autumn, 2.6 ± 1.72 mg C/m
3
in under-ice water, and 14.79 ± 11.25 mg C/m
3
in ice. The contribution of SPF to total phytoplankton biomass depended on the season and ranged from 29 to 95%; the contribution of SPF to sympagic communities averaged 66%. The size structure of photosynthetic flagellates varied by seasons. Flagellates with a cell size of 6–10 µm dominated in summer plankton and in the ice. Flagellates with a cell size of 3–6 µm prevailed in autumn and in the under-ice water. The obtained data of SPF abundance showed higher values of the total phytoplankton biomass of the White Sea in the autumn–winter period compared with the estimates obtained previously. Applying the method of epifluorescence microscopy confirmed the idea that photosynthetic flagellates were the main producers in the winter period as well as in the summer when the biomass of planktonic algae with cell size exceeding 10 µm is low.
The distribution of primary production (PP), chlorophyll
a
concentration (Chl
a
), and size structure of the phytoplankton community were studied in the Kara Sea during the first-year ice retreat in ...late June 2021. The maximum value of water column PP (IPP) reached 1352 mgC m
–2
day
–1
. The ice-edge phytoplankton bloom was characterized by high averaged of IPP and Chl
a
integrated in the photosynthetic layer (Chl
phs
) values: 740 mgC m
–2
day
–1
and 81.40 mg m
–2
, respectively. The highest IPP values were observed at sites where Chl
a
was concentrated in the upper mixed layer or where the subsurface chlorophyll maximum coincided with the pycnocline. Over the area of phytoplankton bloom, the contribution of microphytoplankton (>20 µm) to the total IPP and Chl
phs
was 92 and 82%, respectively. Contribution of picophytoplankton (<3 µm) to the total PP increased along the depth until reaching the lower margin of layer of photosynthesis, from 3 to 70%, on average. No similar pattern has been observed for vertical distribution of Chl
a
. This pattern was evidenced by an increase in the chlorophyll specific carbon fixation rate (assimilation number) of picophytoplankton with depth under low insolation conditions.
