As colder Hornsund, showing higher TBN and BBM values, is influenced by
Arctic inflows, the bacteria present in this fjord may be also of Arctic origin, and
therefore be better adapted to the lower water temperatures (Børsheim and
Drinkwater 2014) than microorganisms occurring in more “Atlantic” Kongsfjorden.
Another parameter influencing bacterial abundance is food availability.
According to Węsławski et al. (2006), bird populations in Hornsund are twice as
numerous as in Kongsfjorden. Some species are even more abundant. For example,
the little auk (Alle alle) colonies are consist of approximately 5 times more individuals in Hornsund than in Kongsfjorden. That corresponds to the greater consumption, and therefore easily affects the amount of faeces and organic matter
which may be introduced to the fjord waters by e.g. surface runoff, providing an
additional nourishment source for bacteria. Moreover, an increased phytoplankton
biomass was observed in Hornsund (Piwosz et al. 2009). Phytoplankton itself, or its
excreted products are important nutrient sources for bacteria (Sharp 1977;
Obernosterer and Herndl 1995; Larsson and Hagsröm 1979).
The higher TBN detected in the surface waters of Hornsund may be positively
correlated with the greater amounts of particulate organic matter (POM) and particulate inorganic matter (PIM) detected in this layer (database of IOPAN: GAME
project, unpublished data). POM serves as the food source for microorganisms, and
PIM coming e.g. from melting glaciers (Björkman et al. 2014) provides habitat for
bacterial consortia, therefore favourable conditions were provided. Considering
Kongsfjorden, higher TBN and BBM values in KG2 water column may be the
result of activity of glacial river occurring in that region.
Water temperature profiles together with the salinity (Fig. 3c, d) enable us to
localize the pycnocline, which as a result of water density changes, facilitates
slowdown of microorganisms sedimentation rates and thus increased amounts of
bacterial cells in this layer may be observed. Increased TBN values were observed
in Kongsfjorden in proximity of the pycnocline, which was localized based on the
salinity and temperature curves at depth of around 10–30 m. Similar phenomenon
was registered in research made by Jankowska et al. (2005) in the same fjord.
Apart from factors mentioned above, other parameters, such as bacteriovory and
lysis reduce bacterial number (Payet and Suttle 2008) which may play a significant
role in Kongsfjorden, however the exact relationships were not studied in this
research.
In the literature there are several informations regarding the biomass in Arctic
waters, however different methods of obtaining those data (application of various
conversion factors for carbon or calculating BBM from TBN) create significant
problems. In the papers mentioned in Table 1, various units of biomass occur,
therefore a straightforward comparison is impossible.
Acknowledgments The authors would like to thank the staff of the Oceania from AREX 2013
cruise for their cooperation during measurements and for making unpublished environmental data
available. We would like to express special thanks to Jakub Kowalczyk, Daniel Rak and Jan
Marcin Węsławski for help and support and IOPAS Archive of hydrographical data for providing
necessary data.
Microbiological Survey in Two Arctic Fjords …
123
Arctic inflows, the bacteria present in this fjord may be also of Arctic origin, and
therefore be better adapted to the lower water temperatures (Børsheim and
Drinkwater 2014) than microorganisms occurring in more “Atlantic” Kongsfjorden.
Another parameter influencing bacterial abundance is food availability.
According to Węsławski et al. (2006), bird populations in Hornsund are twice as
numerous as in Kongsfjorden. Some species are even more abundant. For example,
the little auk (Alle alle) colonies are consist of approximately 5 times more individuals in Hornsund than in Kongsfjorden. That corresponds to the greater consumption, and therefore easily affects the amount of faeces and organic matter
which may be introduced to the fjord waters by e.g. surface runoff, providing an
additional nourishment source for bacteria. Moreover, an increased phytoplankton
biomass was observed in Hornsund (Piwosz et al. 2009). Phytoplankton itself, or its
excreted products are important nutrient sources for bacteria (Sharp 1977;
Obernosterer and Herndl 1995; Larsson and Hagsröm 1979).
The higher TBN detected in the surface waters of Hornsund may be positively
correlated with the greater amounts of particulate organic matter (POM) and particulate inorganic matter (PIM) detected in this layer (database of IOPAN: GAME
project, unpublished data). POM serves as the food source for microorganisms, and
PIM coming e.g. from melting glaciers (Björkman et al. 2014) provides habitat for
bacterial consortia, therefore favourable conditions were provided. Considering
Kongsfjorden, higher TBN and BBM values in KG2 water column may be the
result of activity of glacial river occurring in that region.
Water temperature profiles together with the salinity (Fig. 3c, d) enable us to
localize the pycnocline, which as a result of water density changes, facilitates
slowdown of microorganisms sedimentation rates and thus increased amounts of
bacterial cells in this layer may be observed. Increased TBN values were observed
in Kongsfjorden in proximity of the pycnocline, which was localized based on the
salinity and temperature curves at depth of around 10–30 m. Similar phenomenon
was registered in research made by Jankowska et al. (2005) in the same fjord.
Apart from factors mentioned above, other parameters, such as bacteriovory and
lysis reduce bacterial number (Payet and Suttle 2008) which may play a significant
role in Kongsfjorden, however the exact relationships were not studied in this
research.
In the literature there are several informations regarding the biomass in Arctic
waters, however different methods of obtaining those data (application of various
conversion factors for carbon or calculating BBM from TBN) create significant
problems. In the papers mentioned in Table 1, various units of biomass occur,
therefore a straightforward comparison is impossible.
Acknowledgments The authors would like to thank the staff of the Oceania from AREX 2013
cruise for their cooperation during measurements and for making unpublished environmental data
available. We would like to express special thanks to Jakub Kowalczyk, Daniel Rak and Jan
Marcin Węsławski for help and support and IOPAS Archive of hydrographical data for providing
necessary data.
Microbiological Survey in Two Arctic Fjords …
123