Changes in the Community Structure of Under-Ice and Open-Water Microbiomes in Urban Lakes Exposed to Road Salts

Fournier, Isabelle B.; Lovejoy, Connie; Vincent, Warwick F.

doi:10.3389/fmicb.2021.660719

Cited by 18 publications

(16 citation statements)

References 96 publications

(123 reference statements)

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“…Contrary to expectations, mean under-ice ASV richness was not different from summer, considering all layers or without hypolimnetic communities. A similar result was found in urban lakes showing no difference in alpha diversity of surface bacterioplankton (Fournier et al, 2021). Only the exclusion of summer hypolimnetic communities indicated a seasonal difference.…”

Section: Summer Versus Under-ice Bacterial Communitiessupporting

confidence: 84%

Temporal and spatial differences of the under-ice microbiome are linked to light transparency and chlorophyll-a

Obertegger

2022

Hydrobiologia

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Under-ice community dynamics are barely understood. Temporal and spatial studies are needed to fully understand the consequences of a declining ice cover on microbial biodiversity. Here, bacterial communities of different years (2015, 2017–2021) and layers (upper and lower euphotic layer, euphotic layer, hypolimnion) were assessed by Illumina sequencing of the 16S rRNA gene. Alpha- and beta-diversity of summer and under-ice hypolimnetic communities were similar, and a seasonal difference was found only when excluding summer hypolimnetic communities. Similarly, in non-metric multidimensional scaling (NMDS), summer and under-ice communities were different even though hypolimnetic communities were similar. Investigating under-ice conditions, the year 2017 showed highest under-ice light and chlorophyll-a while 2021 showed no under-ice light and lowest chlorophyll-a. Under-ice communities were not linked to layer differences implying that a spatial distinction under ice was less important than in summer, especially in years with little or no under-ice light. Most under-ice bacterial classes and ASVs showed direct and indirect dependencies on light availability and primary production. Similarly in NMDS with only under-ice communities, light transparency and primary production were important. In the future, ice conditions with less snow cover might lead to bacterial communities similar to that of high-light years (2017, 2018, 2020).

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Section: Summer Versus Under-ice Bacterial Communitiessupporting

confidence: 84%

Temporal and spatial differences of the under-ice microbiome are linked to light transparency and chlorophyll-a

Obertegger

2022

Hydrobiologia

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“…The high Chl‐ a to biovolume ratio (Figure ) further suggests that algae incorporated into ice are smaller but have a higher Chl‐ a content. Small cell size with a high cellular concentration of photosynthetic pigments may be a strategy to persist in cold and low light, as has been previously observed for winter under‐ice phytoplankton (Figure 3 in Fournier et al., 2021). It is, however, noteworthy that 19 phytoplankton taxa were entirely missing from the ice and that the overall cell abundance and biovolumes were higher in the water, indicating that not all phytoplankton could be incorporated and potentially overwinter in the ice.…”

Section: Discussionsupporting

confidence: 59%

Hidden Stores of Organic Matter in Northern Lake Ice: Selective Retention of Terrestrial Particles, Phytoplankton and Labile Carbon

et al. 2021

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Over the last few decades, global warming has led to widespread shrinking of the cryosphere and has brought a sense of urgency toward the study of ice habitats. One of the most heavily impacted cryospheric habitats is freshwater ice. Climate change is leading to substantial reductions in the thickness and duration of lake and river ice cover worldwide (Sharma et al., 2019;Wrona et al., 2016). In the northern hemisphere, ice in lakes and rivers freezes an average of 5.8 days later and melts 6.5 days earlier than 100 years ago, based on the measurements taken between the years 1846and 1995(Magnuson, et al., 2000. Global air temperatures increased 1.2°C during this period. The majority of boreal and Arctic lakes are still ice-covered for six to ten months a year, and the potential importance of this cold and dark period on ecosystem structure and function is increasingly recognized (Grosbois & Rautio, 2018;Hampton et al., 2017;Schneider et al., 2017). Considering that ice-covered lakes include nearly 50% of the world's lakes, there is a pressing Abstract Around 50% of the world's lakes freeze seasonally, but the duration of ice-cover is shortening each year and this is likely to have broad limnological consequences. We sampled freshwater ice and the underlying water in 19 boreal and polar lakes to evaluate whether lake ice contains an inoculum of algae, nutrients, and carbon that may contribute to lake ecosystem productivity. Boreal and Arctic lakes differed in ice duration (6 vs. >10 months), thickness (70 vs. 190 cm), and quality (predominantly snow ice vs. black ice), but in all lakes, there were consistent differences in biological and biogeochemical composition between ice and water. Particulate fractions were often more retained while most dissolved compounds were excluded from the ice; for example, the ice had more terrestrial particulate carbon, measured as fatty acid biomarkers (averages of 1.1 vs. 0.3 µg L −1 ) but lower dissolved organic carbon (2.2 vs. 5.7 mg C L −1 ) and inorganic phosphorus concentrations (4.0 vs. 7.5 µg C L −1 ) than the underlying water. The boreal ice further had three times higher chlorophyll-a, than the water (0.9 vs. 0.3 µg L −1 ). Of the dissolved fractions, the contribution of protein-like compounds was higher in the ice, and this in all lakes. These labile compounds would become available to planktonic microbes when the ice melts. Our results show that freshwater ice has an underestimated role in storage and transformation in the biogeochemical carbon cycle of ice-covered lake ecosystems.Plain Language Summary Winter ice cover of 1-2 m thickness can comprise 20%-70% of the total lake depth in boreal and Arctic lakes. While sea ice is known to contain substantial quantities of carbon and organisms that at ice melt contribute to biological production in the underlying water column, little is known about the composition of lake ice and its role in storage of organic carbon. Our analyses of 19 boreal and Arctic lakes revealed large but different stores of organic material in lake ...

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“…Cells for pigment analysis were collected by filtration until clogging onto 0.7-μm GF/F filters, which were stored below −50°C until analysis. The pigments were extracted from the filters with 95% MeOH, analyzed by HPLC as described in Fournier et al (2021) , and attributed to specific taxonomic groups according to Roy et al (2011) . Bacteria and phytoplankton FCM samples were analyzed with a BD Accuri™ C6 flow cytometer (BD Biosciences).…”

Section: Methodsmentioning

confidence: 99%

Size-Fractionated Microbiome Structure in Subarctic Rivers and a Coastal Plume Across DOC and Salinity Gradients

et al. 2022

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Little is known about the microbial diversity of rivers that flow across the changing subarctic landscape. Using amplicon sequencing (rRNA and rRNA genes) combined with HPLC pigment analysis and physicochemical measurements, we investigated the diversity of two size fractions of planktonic Bacteria, Archaea and microbial eukaryotes along environmental gradients in the Great Whale River (GWR), Canada. This large subarctic river drains an extensive watershed that includes areas of thawing permafrost, and discharges into southeastern Hudson Bay as an extensive plume that gradually mixes with the coastal marine waters. The microbial communities differed by size-fraction (separated with a 3-μm filter), and clustered into three distinct environmental groups: (1) the GWR sites throughout a 150-km sampling transect; (2) the GWR plume in Hudson Bay; and (3) small rivers that flow through degraded permafrost landscapes. There was a downstream increase in taxonomic richness along the GWR, suggesting that sub-catchment inputs influence microbial community structure in the absence of sharp environmental gradients. Microbial community structure shifted across the salinity gradient within the plume, with changes in taxonomic composition and diversity. Rivers flowing through degraded permafrost had distinct physicochemical and microbiome characteristics, with allochthonous dissolved organic carbon explaining part of the variation in community structure. Finally, our analyses of the core microbiome indicated that while a substantial part of all communities consisted of generalists, most taxa had a more limited environmental range and may therefore be sensitive to ongoing change.

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Changes in the Community Structure of Under-Ice and Open-Water Microbiomes in Urban Lakes Exposed to Road Salts

Cited by 18 publications

References 96 publications

Temporal and spatial differences of the under-ice microbiome are linked to light transparency and chlorophyll-a

Temporal and spatial differences of the under-ice microbiome are linked to light transparency and chlorophyll-a

Hidden Stores of Organic Matter in Northern Lake Ice: Selective Retention of Terrestrial Particles, Phytoplankton and Labile Carbon

Size-Fractionated Microbiome Structure in Subarctic Rivers and a Coastal Plume Across DOC and Salinity Gradients

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