Ice Melt-Induced Variations of Structural and Functional Traits of the Aquatic Microbial Community along an Arctic River (Pasvik River, Norway)

Abstract

The effects of climate change-induced ice melting on the microbial communities in different glacial-fed aquatic systems have been reported, but seasonal dynamics remain poorly investigated. In this study, the structural and functional traits of the aquatic microbial community were assessed along with the hydrological and biogeochemical variation patterns of the Arctic Pasvik River under riverine and brackish conditions at the beginning (May = Ice-melt (−)) and during the ice-melting season (July = Ice-melt (+)). The microbial abundance and morphometric analysis showed a spatial diversification between the riverine and brackish stations. Results highlighted different levels of microbial respiration and activities with different carbon and phosphorous utilization pathways, thus suggesting an active biogeochemical cycling along the river especially at the beginning of the ice-melting period. At Ice-melt (−), Gammaproteobacteria and Alphaproteobacteria were dominant in riverine and brackish stations, respectively. Conversely, at Ice-melt (+), the microbial community composition was more homogeneously distributed along the river (Gammaproteobacteria > Alphaproteobacteria > Bacteroidetes). Our findings provide evidence on how riverine microbial communities adapt and respond to seasonal ice melting in glacial-fed aquatic ecosystems.

First report on pollutant accumulation and associated microbial communities in the freshwater sponge Spongilla lacustris (Linnaeus, 1759) from the sub‐Arctic Pasvik River (Norway)

“…Dissolved oxygen, pH, and redox values were 93.9 mg/L, 7.2, and 198 mV, respectively, whereas total dissolved solids were 228 ppm, as it was previously reported by Papale et al (2021). Bacterial community diversity and activities in water and sediment were reported previously (Papale et al, 2021, and Papale, Rizzo, et al, 2022, respectively), along with data on heavy metal (HM)‐pollution and HM‐tolerant cultivable bacterial communities (Caputo et al, 2019) and persistent organic pollutant (POP) concentrations in sediments (Papale, Rizzo, et al, 2022). Data from Papale et al (2021); Papale, Rizzo, et al (2022); and Caputo et al (2019) were used for statistical analyses (see below) and reported in Table S1.…”

“…At sampling time, sediment and water samples were contextually collected in duplicates within a 10‐cm radius of the sponges (Papale et al, 2021; Papale, Rizzo, et al, 2022). Dissolved oxygen, pH, and redox values were 93.9 mg/L, 7.2, and 198 mV, respectively, whereas total dissolved solids were 228 ppm, as it was previously reported by Papale et al (2021).…”

“…At sampling time, sediment and water samples were contextually collected in duplicates within a 10‐cm radius of the sponges (Papale et al, 2021; Papale, Rizzo, et al, 2022). Dissolved oxygen, pH, and redox values were 93.9 mg/L, 7.2, and 198 mV, respectively, whereas total dissolved solids were 228 ppm, as it was previously reported by Papale et al (2021). Bacterial community diversity and activities in water and sediment were reported previously (Papale et al, 2021, and Papale, Rizzo, et al, 2022, respectively), along with data on heavy metal (HM)‐pollution and HM‐tolerant cultivable bacterial communities (Caputo et al, 2019) and persistent organic pollutant (POP) concentrations in sediments (Papale, Rizzo, et al, 2022).…”

Benthic Microbial Communities in a Seasonally Ice-Covered Sub-Arctic River (Pasvik River, Norway) Are Shaped by Site-Specific Environmental Conditions

“…Sediment samples (25–70 cm depth; except for St. 6) were manually collected from nine stations along the Pasvik River at the beginning and ongoing ice-melting [(i.e., Ice-melt(−): 22–29 May; (Ice-melt(+): 17–24 July)] [ 10 , 13 ] ( Figure 1 ). The stations were classified as riverine (Stations 9, 5, 1, 2, and 8) or brackish (Stations 3, 7, 6, and 4).…”

“…Sediments were mainly composed of sand (granulometry fraction between approximately 0.062 and 2 mm) and mud (fraction < 62 µm) [ 10 ]. The major physical–chemical water parameters have been reported elsewhere [ 10 , 13 ].…”