Photosynthesis ecophysiology of polar Vaucheria sp. – inter-annual comparison

The Vaucheria sp. microbial mats represent the most important primary producer in the tidal flat in Adventdalen, Svalbard. Its photosynthetic activity was monitored ex situ in a microcosm in late Arctic summer in 2016 and 2017 using variable chlorophyll fluorescence measurements with blue and red excitation lights. The effective quantum yield (FPSII) was measured, and the photosynthetic relative electron transport rate (rETR) was calculated. During the measurement period, the microclimate data, air temperature and photosynthetically active radiation (PAR), were recorded as well. Year 2016 was slightly warmer than year 2017. Despite of higher maximum PAR values found in 2016, the mean irradiance reached higher values in 2017 than 2016. When using red light excitation, the rETR and effective quantum yield values were lower than those measured using blue excitation light in 2016. However, opposite results were recorded in 2017, indicating thus rather sample-specific differences. According to redundancy analysis, the PAR was confirmed as the main driver of photosynthesis in late Arctic summer in both years. No serious photoinhibition, expressed as serious systematic decline of the rETR, was observed in both years indicating rapid photoacclimation of Vaucheria sp. photosynthesis to changing light environment. The air temperature was found to be less important driver of the photosynthetic activity. The inter-annual comparisons showed increased photosynthetic activity in 2017, probably caused by higher PAR in 2017, by differences in microcosmos design and/or heterogeneity of samples

Biodiversity and ecological classification of cryptogamic soil crusts in the vicinity of Petunia Bay, Svalbard

The objective of this study was to describe various types of Arctic soil crust that were collected in the vicinity of Petunia Bay, Svalbard in the 2012 summer season. The photosynthetically active area of different soil crust samples was estimated by a chlorophyll fluorescence imaging camera. Biodiversity of cyanobacteria and microalgae from the collected soil crusts was analyzed using a stereomicroscopy and light microscopy. In most cases, cryptogamic crusts were dominated by cyanobacteria such as Gloeocapsa sp., Nostoc sp., Microcoleus sp., Scytonema sp., and Chroococcus sp. The dominant green microalgae were Coccomyxa sp., Hormotila sp., and Trebouxia sp. which commonly occurred in a lichenised soil crust. Soil crusts that were located in conditions with high water content were dominated by Nostoc sp. Cryptogamic soil crusts from the studied area can be divided into three different types and classified: (1) black-brown soil crusts (with low diversity of cyanobacteria and microalgae), (2) brown soil crusts (with high diversity of cyanobacteria and microalgae) and (3) grey-brown soil crusts (with low diversity of cyanobacteria and algae). The occurrence of similar soil crust types were compared at different altitudes. Altitude does not affect the biodiversity of cyanobacteria and microalgae. However, cyanobacteria and microalgae abundance increases with altitude

Photosynthetic activity of Arctic Vaucheria (Xanthophyceae) measured in microcosmos

The xanthophycean alga Vaucheria inhabits very variable, and hence extreme, ecosys-tem of polar river estuaries. Therefore, it represents a unique system for the study of adaptation/acclimatization mechanisms. Since the ecophysiological measurements cannot be performed in the field directly, a piece of Vaucheria community collected in the Adventelva estuary, Longyearbyen, Svalbard, was taken to a microcosmos in order to study it. The set of instrumentation for measurement of ecophysiological parameters was constructed for such a field study. The community structure and photosynthetic activity expressed as the dissolved oxygen concentration and effective quantum yield (and hence relative electron transfer rate) were measured. The study defined relations between encountered environmental conditions and Vaucheria photosynthetic activity in late Arctic summer. The community consisted almost entirely of Vaucheria thalli; small marine pennate diatoms were rare. The microcosmos was proved functional since the structure of the community remained unaffected. Both methods of photosynthetic activity measurement were able to record its diel changes during 10 days lasting incubation. Although only weak correlation was found between the oxygen concentration and variable chlorophyll, probably due to the time necessary for oxygen diffusion, data from fluorometers were highly correlated. The Vaucheria expressed diel cycles in the photosynthetic activity, and the photosynthetically active radiation was the main driving factor. The incubation in microcosmos proved to be suitable for ecophysiological studies which will include the addition of tidal cycles and more sophisticated protocols for photosynthetic activity measurement

Feasibility studies on future phycological research in polar regions

Cyanobacteria and algal communities are essential in the process of initial primary succession following landscape deglaciation. Near the glacial front, a shallow wetland zone is maintained by melting ice. Here, algal mats and crusts quickly develop. The ground in all of these wet habitats is cold due to the close presence of the glacial front and permafrost. Cyanobacteria and algal populations which survive and expand in such extreme cold and unstable environments display special ecological and physiological acclimatization-adaptation characteristics, which enable them to succeed during the initial colonization phase. In this text, it is proposed to use these young microbial ecosystems as feasibility studies for developing the necessary methodology to assess the algal response to climate change. Cyanobacteria and algal communities are the most appropriate model microorganisms for such study because of their global universality, environmental sensitivity, fast reproductive potential and relatively easy experimental manipulation. We propose the microbial studies on three different mutually complementary levels : ・Study of diversity, structure and life strategies of Cyanobacteria and algae participating in the initiation of primary succession. ・Study of primary production, nitrogen fixation and nutrient utilization in natural and nutritionally-manipulated experimental set-ups. ・Study of physiological response of Cyanobacteria and algae to temperature change. The processes of primary succession have been widely studied by Japanese, as well as Czech, scientists in polar regions during recent times. In this paper, we review phycological studies which have been carried out in the Antarctic and the Arctic, and sounded on feasibility studies in this field

Phototrophic microflora colonizing substrates of man-made origin in Billefjorden Region, Central Svalbard

Substrates created by human have a significant impact on Arctic terrestrial environment. These substrates are new potential niche for microbial biota, which may have several essential chemical agents supporting microbial growth. Wood, concrete, brick, ceramic and other different building materials, which have been introduced by human in this iso-lated environment, are colonized with terrestrial and aero-terrestrial microorganisms living in the natural niches near the substrates like soil, rocks, etc., but these materials newly-introduced to Svalbard terrestrial ecosystems can also work as vectors for invasion of new species into the environment. We have collected different types of artificial substrates mainly in the region of Petuniabukta bay and studied the species composition of microbial phototrophs living there. A total of 25 taxa of cyanobacteria and algae were documented on different types of substrates like brick walls, concrete, glass, iron, wood and plastic. A commonality in species diversity was observed with similar substrates in temperate climatic regions. Fottea stichococcoides, Sphaerococcomyxa olivacea, Polysphaera composita and Diplosphaera chodatii were first time recorded from Svalbard Archipelago

Exploitation of databases in polar research - Data evaluation and outputs

The increasing number of observations and floristic sample analyses provided by the Centre for Polar Ecology, Faculty of Science, University of South Bohemia in České Budějovice, Czech Republic (CPE), led to development of the sample database (SampleDTB). At present, the Sample DTB contains records on total of 318 samples from 135 sites. Total of 254 taxa at level of genera or species were observed. For database functionality tests, two datasets were selected. The first one consisted of samples collected by ALGO groups in frame of Polar Ecology course organized by the CPE in 2011-2014 (ALGO dataset). The second one consisted of samples collected in Bulgaria in 2013 (BG dataset). The ALGO dataset contains records on total of 188 samples from 94 sites. Total of 216 taxa (genera or species) were observed. The majority of habitats sampled were streams and the most frequently sampled communities were layer-forming communities like periphyton, epilithon and biofilms. The most dominant classes observed in ALGO dataset were diatoms and cyanobacteria. The unconstrained canonical analysisrevealed that the environment type significantly affected the taxonomical composition observed. In the BG dataset, 16 samples from 4 sites were recorded. Total of 40 taxa (genera or species) were observed. Majority of habitats sampled included streams and shallow pools and the communities sampled were restricted to periphyton, epiphyton and epilithon. Similarly to ALGO dataset, the most dominant classes in BG dataset were Cyanophyceae and diatoms. Due to low number of samples, no multivariate analysis was performed in the BG dataset. These exports and further analyses proved functionality of the SampleDTB database

Screening of growth phases of Antarctic algae and cyanobacteria cultivated on agar plates by chlorophyll fluorescence imaging

Recently, chlorophyll fluorescence imaging is frequently used non-invasive method to monitor the metabolic state and photosynthetic activities of vascular plants and other autotrophic organisms. In our study, we used the measurements of chlorophyll fluorescence kinetics to follow the development of culture of Antarctic algae (Macrochloris rubrioleum, Zygnema sp.) and cyanobacteria (Hassalia antarctica, Nostoc commune). On the cultures grown on agar plates, Bold´s Basal Medium (BBM), slow Kautsky kinetics supplemented with saturation pulses were measured repeatedly in a week interval. On the kinetics, typical points (OPSMT) were distinguished and species-specific and time of cultivation-dependent differences in shape of the OPSMT kinetics evaluated. We tested sensitivity of various chlorophyll fluorescence parameters to cultivation time on agar plates. In the algae, the most pronounced changes were the decrease in maximum quantum yield of photosystem II (FV/FM) and quenching of basal chlorophyll fluorescence qF0 (M. rubrioleum, Zygnema sp.). In cyanobacteria, chlorophyll fluorescence parameters did not show clear trends with the time of cultivation. F0 quenching (qF0) reached positive values in H. antarctica, while it was negative in N. commune. In both cases, however, qF0 showed an increase with cultivation time. The differences are discussed as well as the potential of the emerging area of the application of chlorophyll fluorescence imaging for evaluation of photosynthetic performance of algal/cyanobacterial cultures on agar plates

Nutrient requirements of polar Chlorella-like species

Eukaryotic micro-algae, well adapted to extremely low and varying temperatures, varying light intensities, as well as low availability of essential macronutrients and other resources, represent ideal producers in low-temperature biotechnological processes. In order to identify the nutrient requirements of six biotechnologically perspective Arctic and Antarctic soil Chlorella-like strains at various temperature and light regimes, the algae were cultivated in a unit for cross gradients of temperature (-4 to 24°C) and irradiance (5 to 65 µmol m-2 s-1), and at different nutrient treatments in each temperature-irradiance combination. The nutrient treatments included two different carbon (bicarbonate and carbonate concentrations of 1 and 5 mM) and nitrogen (nitrate concentrations of 50 amd 100 µM and ammonium concentrations 100 and 500 µM) forms at two different concentrations for each. Temperature and irradiance growth requirements were similar in the majority of strains reflecting thus comparable conditions in the original microhabitat, regardless of its geographic position. All studied strains tolerated low temperatures (1 to 5°C), but were able to grow even at temperatures above 20°C, thus, they were considered to be psychrotolerant. All experimental strains were able to grow at very low irradiances. Nutrient manipulation either did not affect the growth limits and optimum, or narrowed the growth optima; the response was strain-specific. Ammonium and nitrate additions resulted in decreased growth rates in all tested strains, with the exception of one strain in which growth stimulation was observed. The decrease in growth rate was probably due to nutrient oversaturation in the inhibited strains. Carbonate addition stimulated growth of all strains. Bicarbonate also increased the growth rate in all strains with one exception, in which bicarbonate inhibited growth, indicating thus carbon limitation during cultivation and different carbon uptake mechanisms