Gradient of algal and cyanobacterial assemblages in a temporary lake with melting water at Solorina Valley, James Ross Island, Antarctica

The aim of presented study is to contribute to species list of algae, cyanobacteria and diatoms from moist localities of James Ross Island, Solorina Valley (63 53 S, 57 48 W) in particular. In 2012, samples of microbiological mats were taken from a bottom of shallow depression close to a seashore line. The sampling site has been filled with melt- ing water from glacier for some weeks preceding the collection. On collection date, however it was dried out. The samples were analysed using optical microscopy approach after the transport of samples to Czech Republic (Masaryk University, Brno). Algal and cyanobacterial taxa forming the microbiological mats were determined according to their morphological characteristics and the frequencies of individual taxa occurrence evalu- ated. Species richness differed between individual sampling sites located across a shallow depression suggesting an ecological role of duration of stagnant water for bio- diversity in temporary freshwater ponds. Altogether, 37 algal and cyanobacterial taxa were found. While 23 taxa present in the centre of the depression, only 10 taxa were found close to the margin where the dry period was the longest.Druhová diverzita řas a sinic byla sledována v dočasné maloplošné nádrži vyplněné tavnou vodou - v Antarktidě, ostov Jamese Rosse, Solorina Valley.The aim of presented study is to contribute to species list of algae, cyanobacteria and diatoms from moist localities of James Ross Island, Solorina Valley (63 53 S, 57 48 W) in particular. In 2012, samples of microbiological mats were taken from a bottom of shallow depression close to a seashore line. The sampling site has been filled with melt- ing water from glacier for some weeks preceding the collection. On collection date, however it was dried out. The samples were analysed using optical microscopy approach after the transport of samples to Czech Republic (Masaryk University, Brno). Algal and cyanobacterial taxa forming the microbiological mats were determined according to their morphological characteristics and the frequencies of individual taxa occurrence evalu- ated. Species richness differed between individual sampling sites located across a shallow depression suggesting an ecological role of duration of stagnant water for bio- diversity in temporary freshwater ponds. Altogether, 37 algal and cyanobacterial taxa were found. While 23 taxa present in the centre of the depression, only 10 taxa were found close to the margin where the dry period was the longest

Gradient of algal and cyanobacterial assemblages in a temporary lake with melting water at Solorina Valley, James Ross Island, Antarctica

The aim of presented study is to contribute to species list of algae, cyanobacteria and diatoms from moist localities of James Ross Island, Solorina Valley (63° 53' S, 57° 48' W) in particular. In 2012, samples of microbiological mats were taken from a bottom of shallow depression close to a seashore line. The sampling site has been filled with melt-ing water from glacier for some weeks preceding the collection. On collection date, however it was dried out. The samples were analysed using optical microscopy approach after the transport of samples to Czech Republic (Masaryk University, Brno). Algal and cyanobacterial taxa forming the microbiological mats were determined according to their morphological characteristics and the frequencies of individual taxa occurrence evalu-ated. Species richness differed between individual sampling sites located across a shallow depression suggesting an ecological role of duration of stagnant water for bio-diversity in temporary freshwater ponds. Altogether, 37 algal and cyanobacterial taxa were found. While 23 taxa present in the centre of the depression, only 10 taxa were found close to the margin where the dry period was the longest

Biodiversity of freshwater algae and cyanobacteria on deglaciated northern part of James Ross Island, Antarctica. A preliminary study.

Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant- arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach.Byly studovány sladkovodní řasy a sinice ostrova Jamese Rosse, Antarktida. Výsledky analýzy biodiverzity jsou uvedeny podle charakteru stanoviště.Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant- arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach

Biodiversity of freshwater algae and cyanobacteria on deglaciated northern part of James Ross Island, Antarctica. A preliminary study.

Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant-arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach. We plan to sample those locations of the James Ross Island that have never been investigated before for future studie

Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient.

In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluo- rescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photo- chemistry (FV/FM) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond QA, and the yield of electron transport beyond QA is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PIabs) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp.Stres solí byl posuzován pomocí rychlé indukční kinetiky fluorescence chlorofylu OJIP. Bylo uskutečněno mezidruhové srovnání mezi řasami Zygnema sp. a Klebsormidium sp.In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluo- rescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photo- chemistry (FV/FM) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond QA, and the yield of electron transport beyond QA is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PIabs) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp

Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient

In this study, we investigated the effects of salt stress (2 mM NaCl) on excitation energy transfer from light harvesting complexes to photosystem II (PS II) in two Antarctic algal species: Klebsormidium sp. and Zygnema sp. Short-term salt stress led to a significant changes in the shape of chlorophyll fluorescence transient (OJIP). Analyses of the polyphasic fluorescence transients (OJIP) showed that the fluorescence yield at the phases J, I and P declined considerably with the time of exposition to salt stress. In both experimental species, OJIP transients reached lowest values of chlorophyll fluorescence signal after 30/60 min. of NaCl exposition. Then, OJIP shape and chlorophyll fluo-rescence showed species-specific recovery and rised towards original values (about 2/3 of untreated control). Analyses of chlorophyll fluorescence parameters derived from OJIPs showed that salt stress led to a decrease in the maximal efficiency of PS II photo-chemistry (FV/FM) in Zygnema sp. but not Klebsormidium sp. The results indicated that the probability of excitation energy transfer before and beyond QA, and the yield of electron transport beyond QA is limited by salt-induced stress in Zygnema sp. In addition, salt stress resulted in a decrease in the photosynthetic electron transport per PS II reaction center, but both increase and decrease in the trapping per PS II reaction center was found. Performace index (PIabs) was affected negatively in Zygnema sp. but possitively Klebsormidium sp. indicating that the latter species was more resistant to salt stress than Zygnema sp

Photosynthetic characteristics of lichens of genus Umbilicaria from SW Greenland (Nuuk area) in reponse to thallus dehydration.

Thalli of foliose epilithic lichens Umbilicaria arctica and U.hyperborea were collected on the rocks at several locations in the neighbourhood of Nuuk, and transported to the Czech Republic where kept in dry state in dark at 5 oC before experiments. After 48 h rehydration, simultaneous measurements of (1)effective quantum yield (YieldPSII) of photosystem II, (2)photochemical reflectance index (PRI), (3)normalized difference vegetation index (NDVI), (4)chlorophyll fluorescence fast kinetics (OJIP) were made in response to gradual thallus dehydration expressed as water potential (WP). Dehydration-response curves of YieldPSII showed S-curve relationship. In both species, the first signs of inhibition of photosynthetic processes appeared at WP of about -10 MPa. Further dehydration led to a decrease in YieldPSII and, finally, full inhibition of PSII photochemical photosynthetic processes. Critical point for PSII processes was found at WP of about -25 MPa, similarly to other epilithic lichens investigated by this methodVyl studován vztah mezi fůznými fotosyntetickými charakteristikami lišejníků Umbilicaria arctica a Umbilicaria Hyperboera ve vztahu k vyschnutí stélky.Thalli of foliose epilithic lichens Umbilicaria arctica and U.hyperborea were collected on the rocks at several locations in the neighbourhood of Nuuk, and transported to the Czech Republic where kept in dry state in dark at 5 oC before experiments. After 48 h rehydration, simultaneous measurements of (1)effective quantum yield (YieldPSII) of photosystem II, (2)photochemical reflectance index (PRI), (3)normalized difference vegetation index (NDVI), (4)chlorophyll fluorescence fast kinetics (OJIP) were made in response to gradual thallus dehydration expressed as water potential (WP). Dehydration-response curves of YieldPSII showed S-curve relationship. In both species, the first signs of inhibition of photosynthetic processes appeared at WP of about -10 MPa. Further dehydration led to a decrease in YieldPSII and, finally, full inhibition of PSII photochemical photosynthetic processes. Critical point for PSII processes was found at WP of about -25 MPa, similarly to other epilihic lichens investigated by this metho

Dehydration-induced responses of primary photosynthetic processes and spectral reflectance indices in Antarctic Nostoc commune

In this study, we investigated the relationship between relative water content (RWC) of N. commune colonies recorded during gradual dehydration and (i) normalized difference vegetation index (NDVI), (ii) photochemical reflectance index (PRI), and (iii) primary photochemical processes of photosynthesis, effective quantum yield of photosynthetic processes (PhiPSII) in photosystem II particular. PRI increased from -0.05 to 0.02 with RWC decrease from 100% (full hydration) to 0% (dry state). NDVI showed somewhat curvilinear relationship with desiccation with minimum value of 0.25 found at 10% RWC. Negative effect of suprasaturation of N. commune colony with water on effective quantum yield (PhiPSII) was found at RWC range 80-100%. At the RWC range, PhiPSII reached only 50 % of maximum found at RWC of 30%. In general, desiccation-response curve of showed polyphasic character with three main phases (phase I – constant PhiPSII values, phase II – an increase with desiccation at RWC 80-30%, and phase III – sigmoidal decrease with desiccation at RWC 0-30%).Práce je zaměřena na analýzu spektrálních indexů PRI a NDVI, v souvislosti s dehydrací kolonie sinice Nostoc commune. Souběžně s indexy spektrální reflektance byly měřeny a analyzovávy fotosyntetické parametry fluorescence chlorofylu, zejména efektivní kvantový výtěžek fotosyntetických procesů ve fotosystému II (PS II)In this study, we investigated the relationship between relative water content (RWC) of N. commune colonies recorded during gradual dehydration and (i) normalized difference vegetation index (NDVI), (ii) photochemical reflectance index (PRI), and (iii) primary photochemical processes of photosynthesis, effective quantum yield of photosynthetic processes (PhiPSII) in photosystem II particular. PRI increased from -0.05 to 0.02 with RWC decrease from 100% (full hydration) to 0% (dry state). NDVI showed somewhat curvilinear relationship with desiccation with minimum value of 0.25 found at 10% RWC. Negative effect of suprasaturation of N. commune colony with water on effective quantum yield (PhiPSII) was found at RWC range 80-100%. At the RWC range, PhiPSII reached only 50 % of maximum found at RWC of 30%. In general, desiccation-response curve of showed polyphasic character with three main phases (phase I – constant PhiPSII values, phase II – an increase with desiccation at RWC 80-30%, and phase III – sigmoidal decrease with desiccation at RWC 0-30%)

Dehydration-induced responses of primary photosynthetic processes and spectral reflectance indices in Antarctic Nostoc commune

In this study, we investigated the relationship between relative water content (RWC) of N. commune colonies recorded during gradual dehydration and (i) normalized difference vegetation index (NDVI), (ii) photochemical reflectance index (PRI), and (iii) primary photochemical processes of photosynthesis, effective quantum yield of photosynthetic processes (FPSII) in photosystem II particular. PRI increased from -0.05 to 0.02 with RWC decrease from 100% (full hydration) to 0% (dry state). NDVI showed somewhat curvilinear relationship with desiccation with minimum value of 0.25 found at 10% RWC. Negative effect of suprasaturation of N. commune colony with water on effective quantum yield (FPSII) was found at RWC range 80-100%. At the RWC range, FPSII reached only 50 % of maximum found at RWC of 30%. In general, desiccation-response curve of showed polyphasic character with three main phases (phase I – constant FPSII values, phase II – an increase with desiccation at RWC 80-30%, and phase III – sigmoidal decrease with desiccation at RWC 0-30%). Non-photochemical quenching (qN) of absorbed light energy showed triphasic dependence on RWC as well. qN showed constant values in the phase I, an increase (phase II), and constant values at severe dehydration (phase III)

Nitrate and ammonium ions contents in field minibioreactors with Antarctic freshwater autotrophs

The content of nitrate and ammonium ions in aquatic environment is an important factor in the development of microorganisms colonies especially in low-nutrient environment. In this study, field experiments using small-volume minibioreactors were performed directly on the James Ross Island in Antarctica in order to describe changes in nitrate and ammonium ions contents in the Antarctic environment The ion concentrations in minibioreactors with local freshwater autotrophs was monitored for increased eutro-phication conditions. The content of nitrogen forms was determined in water samples taken from the minibioreactors regularly. Samples were taken to the laboratory of the Johann Gregor Mendel station where nitrogen content was evaluated using ion-selective electrodes. Furthermore, the freshwater autotrophs was subjected to basic taxonomic study. Closed system of the minibioreactors allowed the monitoring of nitrogen speciation changes which take place in the environment. These changes can be attributed to both the biological activity of microorganisms and external conditions. Increased eutrophication of water did not induce a rapid development of the freshwater autotrophs