Variability of protistan and bacterial communities in two Arctic fjords (Spitsbergen)

Abstract

Krossfjorden and Kongsfjorden are Arctic fjords on the western side of Spitsbergen. These fjords share a common mouth to the open sea, and both are inXuenced by the input of sediment-rich glacial meltwater leading to decreased surface salinity, increased turbidity and decreased light penetration during summer. Earlier classical taxonomic studies had described the pelagic protistan composition of the Kongsfjorden during summer, revealing the dominance of Xagellates of often unresolved taxonomic origin. Only little information existed on microbial eukaryote composition of the Krossfjorden as well as the bacterial composition of both fjords. The aim of the present study was to analyze and compare surface summertime protistan and bacterial communities in both fjords, using molecular approaches (16S and 18S rRNA DGGE, sequencing). Samples were collected three times a week from the central Kongsfjorden over a 1-month period. Additionally, 10 marine and 2 freshwater sites were sampled within a 1-week period in both Kongsfjorden and Krossfjorden. The central Kongsfjorden revealed a relatively stable protistan community over time with dinoXagellates, chlorophytes and small heterotrophs dominating. In contrast, the bacterial community varied over time and appeared to be correlated with the inXow of glacial meltwater. The Kongsfjorden and Krossfjorden were found to harbor distinctive bacterial and eukaryotic communities. We speculate that diVerences in glacial meltwater composition and fjord bathymetry aVect the surface water properties and therefore the observed spatial variability in the community Wngerprints.

Effect of elevated CO<sub>2</sub> on the dynamics of particle-attached and free-living bacterioplankton communities in an Arctic fjord

“…Therefore, caution has to be taken when judging the general validity of our results for the response of the bacterial community to ocean acidification in Arctic waters. In addition, the bacterial community structure in Kongsfjorden can vary considerably seasonally (Piquet et al, 2010). Nevertheless, the fact that other mesocosm studies in a Norwegian fjord found similar results suggests an emerging pattern of secondary effects on PA bacteria under ocean acidification, while FL bacteria stay rather unchanged.…”

“…the runoff of melt water. While the bacterial community was found to be spatially relatively homogenous in Kongsfjorden (Zeng et al, 2009), it was shown to differ significantly from that of a neighbouring fjord with less water exchange (Piquet et al, 2010), indicating spatial variability on a larger scale. A high spatial variability is also present in the factors limiting bacterial growth in the coastal waters of Svalbard (Vadstein, 2011), and this has been proposed to influence the reaction of the bacterial community to CO 2 perturbation .…”

Changes in Marine Prokaryote Composition with Season and Depth Over an Arctic Polar Year

“…Interestingly, we observed that the relative abundance of Betaproteobacteria in surface water samples decreased as a function of distance either from the coast or from the pack ice. A number of large glacial fjords flow into the Western coastal waters off Svalbard (Figure 1) and the Betaproteobacteria have been retrieved from Kongsfjorden there (Zeng et al, 2009(Zeng et al, , 2013Piquet et al, 2010). The group have also been seen to predominate in Arctic pack ice summer melt pools (Brinkmeyer et al, 2004), which might further seed ocean waters upon thawing.…”

Meiofaunal distribution in Hornsund fjord, Spitsbergen

“…Bacteria in the sediments directly impact nutrient and carbon cycles, as they complete the Wnal decomposition step by breaking down organic carbon and making it available for other organisms (Fenchel and Jørgensen 1977;Falkowski et al 2008;Robador et al 2009). However, little information is available about the bacterial community in Spitsbergen fjords (Jankowska et al 2005;Jiang et al 2005;Zeng et al 2009;Piquet et al 2010); thus, the relationship between bacterial activity and organic matter in Hornsund requires further study.…”