Interplay of regional oceanography and biogeochemistry on phytoplankton bloom development in an Arctic fjord

Singh, Archana; David, T. Divya; Tripathy, S.C.; Naik, Ravidas K.

doi:10.1016/j.ecss.2020.106916

Cited by 6 publications

(4 citation statements)

References 48 publications

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“…8 ). A comparable three-stage bloom has been observed a year before in nearby Kongsfjorden [ 97 ]. The replacement of eukaryotic heterotrophs by photoautotrophs (Fig.…”

Section: Resultssupporting

confidence: 66%

The polar night shift: seasonal dynamics and drivers of Arctic Ocean microbiomes revealed by autonomous sampling

Wietz

Bienhold

Metfies

et al. 2021

ISME Communications

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The Arctic Ocean features extreme seasonal differences in daylight, temperature, ice cover, and mixed layer depth. However, the diversity and ecology of microbes across these contrasting environmental conditions remain enigmatic. Here, using autonomous samplers and sensors deployed at two mooring sites, we portray an annual cycle of microbial diversity, nutrient concentrations and physical oceanography in the major hydrographic regimes of the Fram Strait. The ice-free West Spitsbergen Current displayed a marked separation into a productive summer (dominated by diatoms and carbohydrate-degrading bacteria) and regenerative winter state (dominated by heterotrophic Syndiniales, radiolarians, chemoautotrophic bacteria, and archaea). The autumn post-bloom with maximal nutrient depletion featured Coscinodiscophyceae, Rhodobacteraceae (e.g. Amylibacter) and the SAR116 clade. Winter replenishment of nitrate, silicate and phosphate, linked to vertical mixing and a unique microbiome that included Magnetospiraceae and Dadabacteriales, fueled the following phytoplankton bloom. The spring-summer succession of Phaeocystis, Grammonema and Thalassiosira coincided with ephemeral peaks of Aurantivirga, Formosa, Polaribacter and NS lineages, indicating metabolic relationships. In the East Greenland Current, deeper sampling depth, ice cover and polar water masses concurred with weaker seasonality and a stronger heterotrophic signature. The ice-related winter microbiome comprised Bacillaria, Naviculales, Polarella, Chrysophyceae and Flavobacterium ASVs. Low ice cover and advection of Atlantic Water coincided with diminished abundances of chemoautotrophic bacteria while others such as Phaeocystis increased, suggesting that Atlantification alters microbiome structure and eventually the biological carbon pump. These insights promote the understanding of microbial seasonality and polar night ecology in the Arctic Ocean, a region severely affected by climate change.

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“…8 ). A comparable three-stage bloom has been observed a year before in nearby Kongsfjorden [ 97 ]. The replacement of eukaryotic heterotrophs by photoautotrophs (Fig.…”

Section: Resultssupporting

confidence: 66%

The polar night shift: seasonal dynamics and drivers of Arctic Ocean microbiomes revealed by autonomous sampling

Wietz

Bienhold

Metfies

et al. 2021

ISME Communications

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show abstract

“…We observed three distinct bloom stages, featuring phototrophic pioneers (Phaeocystis and Chaetoceros) followed by araphid-pennate diatoms (Grammonema) and centric diatoms (Thalassiosira). A comparable three-stage summer bloom in the preceding year in nearby Kongsfjorden 21 suggests recurrent principles in the ice-free Fram Strait. The swift replacement of eukaryotic heterotrophs by photoautotrophs (Fig.…”

Section: Microbial Succession In the Wscmentioning

confidence: 86%

“…In contrast, temporal records from the polar oceans are rare. Pioneering studies have identified variable numbers, activities and community structures of polar microbes over time and space [14][15][16][17][18][19][20][21] , yet with limited temporal or spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

The Polar Night Shift: Annual Dynamics and Drivers of Microbial Community Structure in the Arctic Ocean

Wietz¹,

Bienhold²,

Metfies³

et al. 2021

Preprint

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Change is a constant in the Arctic Ocean, with extreme seasonal differences in daylight, ice cover and temperature. The biodiversity and ecology of marine microbes across these extremes remain poorly understood. Here, using an array of autonomous samplers and sensors, we portray an annual cycle of microbial biodiversity, nutrient budgets and oceanography in the major biomes of the Fram Strait. In the ice-free West Spitsbergen Current, community turnover followed the solar cycle, with distinct separation of a productive summer state dominated by diatoms and carbohydrate-degrading bacteria, and a regenerative winter state dominated by heterotrophic Syndiniales, radiolarians, chemoautotrophic bacteria and archaea. Winter mixing of the water column replenishing nitrate, phosphate and silicate, and the onset of light were the major turning points. The summer succession of Phaeocystis, Grammonema and Thalassiosira coincided with ephemeral peaks of Formosa, Polaribacter and NS clades, indicating metabolic relationships between phytoplankton and bacteria. In the East Greenland Current, ice cover and greater sampling depth coincided with weaker seasonality, featuring weaker bloom/decay events and an ice-related winter microbiome. Low ice cover and advection of Atlantic Water coincided with diminished abundances of chemoautotrophic bacteria while Phaeocystis and Flavobacteriaceae increased, suggesting that Atlantification alters phytoplankton diversity and the biological carbon pump. Our findings promote the understanding of microbial seasonality in Arctic waters, illustrating the ecological importance of the polar night and providing an essential baseline of microbial dynamics in a region severely affected by climate change.

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“…This fjord receives significant meltwater influx from its tidewater glaciers (Svendsen et al 2002 ), contributing organic and mineral-rich particles to the fjord. The increased intrusion of warmer and saline Atlantic water (Cottier et al 2005 ; David and Krishnan 2017 ; Singh et al 2020 ) affects the phytoplankton bloom phenology (Singh et al 2020 ), macroalgal distribution (Bartsch et al 2016 ; Hop et al 2016 ) and biogeochemical processes in the Kongsfjorden (Iversen and Seuthe 2011 ; Seuthe et al 2011 ). As Kongsfjorden is also rich in organic particles (Sagan and Darecki 2018 ), it forms an ideal site to study particle-attached microbial communities.…”

Section: Methodsmentioning

confidence: 99%

Marine Group-II archaea dominate particle-attached as well as free-living archaeal assemblages in the surface waters of Kongsfjorden, Svalbard, Arctic Ocean

Jain

Krishnan

2021

Antonie van Leeuwenhoek

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Marine archaea are a significant component of the global oceanic ecosystems, including the polar oceans. However, only a few attempts have been made to study archaea in the high Arctic fjords. Given the importance of Archaea in carbon and nitrogen cycling, it is imperative to explore their diversity and community composition in the high Arctic fjords, such as Kongsfjorden (Svalbard). In the present study, we evaluated archaeal diversity and community composition in the size-fractionated microbial population, viz-a-viz free-living (FL; 0.2–3 μm) and particle-attached (PA; > 3 μm) using archaeal V3–V4 16S rRNA gene amplicon sequencing. Our results indicate that the overall archaeal community in the surface water of Kongsfjorden was dominated by the members of the marine group-II (MGII) archaea, followed by the MGI group members, including Nitrosopumilaceae and Nitrososphaeraceae . Although a clear niche partitioning between PA and FL archaeal communities was not observed, 2 OTUs among 682 OTUs, and 3 ASVs out of 1932 ASVs were differentially abundant among the fractions. OTU001/ASV0002, classified as MGIIa, was differentially abundant in the PA fraction. OTU006/ASV0006/ASV0010 affiliated with MGIIb were differentially abundant in the FL fraction. Particulate organic nitrogen and C:N ratio were the most significant variables ( P < 0.05) explaining the observed variation in the FL and PA archaeal communities, respectively. These results indicate an exchange between archaeal communities or a generalist lifestyle switching between FL and PA fractions. Besides, the particles' elemental composition (carbon and nitrogen) seems to play an essential role in shaping the PA archaeal communities in the surface waters of Kongsfjorden. Supplementary Information The online version contains supplementary material available at 10.1007/s10482-021-01547-1.

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Interplay of regional oceanography and biogeochemistry on phytoplankton bloom development in an Arctic fjord

Cited by 6 publications

References 48 publications

The polar night shift: seasonal dynamics and drivers of Arctic Ocean microbiomes revealed by autonomous sampling

The polar night shift: seasonal dynamics and drivers of Arctic Ocean microbiomes revealed by autonomous sampling

The Polar Night Shift: Annual Dynamics and Drivers of Microbial Community Structure in the Arctic Ocean

Marine Group-II archaea dominate particle-attached as well as free-living archaeal assemblages in the surface waters of Kongsfjorden, Svalbard, Arctic Ocean

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