Comparative analysis of temperature courses in Antarctic lakes of different morphology: Study from James Ross Island, Antarctica

Monitoring of physical properties of terrestrial lakes belongs to one of key research activities performed by Czech scientists at James Ross Island. Throughout 2011, water temperature was measured and recorded by dataloggers in 1 h interval in two Antarctic lakes of different size and morphology. The first lake is a large shallow one located in a depression of sedimentary rock (Lachman Lake 1) at the altitude of 10m a.s.l. Lake Dulanek, the second one, is typical small-area water body located on stony glacier surface at the altitude of 220 m a.s.l. Dulanek Lake, thanks to higher altitude, remained frozen for longer period (274 d) of austral winter than Lachman Lake 1 (205 d). Presence of thick snow cover over Dulanek lake during winter period, however, caused higher values of winter minimal temperature (-17.5°C) than those recorded for Lachman lake 1 (several periods below -20.0°C). Mean annual temperature reached -4.6°C and -5.2°C for Lake Dulanek, and Lachman Lake 1, respectively. Shorter summer season accompanied by lower water temperature in Lake Dulanek however, did not bring unfovourable conditions for growth and reproduction of autotrophic organisms. Biomass of autotrophic organisms found in Lake Dulanek was quite high

Novel insights in cryptic diversity of snow and glacier ice algae communities combining 18S rRNA gene and ITS2 amplicon sequencing

Melting snow and glacier surfaces host microalgal blooms in polar and mountainous regions. The aim of this study was to determine the dominant taxa at the species level in the European Arctic and the Alps. A standardized protocol for amplicon metabarcoding using the 18S rRNA gene and ITS2 markers was developed. This is important because previous biodiversity studies have been hampered by the dominance of closely related algal taxa in snow and ice. Due to the limited resolution of partial 18S rRNA Illumina sequences, the hypervariable ITS2 region was used to further discriminate between the genotypes. Our results show that red snow was caused by the cosmopolitan Sanguina nivaloides (Chlamydomonadales, Chlorophyta) and two as of yet undescribed Sanguina species. Arctic orange snow was dominated by S. aurantia, which was not found in the Alps. On glaciers, at least three Ancylonema species (Zygnematales, Streptophyta) dominated. Golden-brown blooms consisted of Hydrurus spp. (Hydrurales, Stramenophiles) and these were mainly an Arctic phenomenon. For chrysophytes, only the 18S rRNA gene but not ITS2 sequences were amplified, showcasing how delicate the selection of eukaryotic ‘universal’ primers for community studies is and that primer specificity will affect diversity results dramatically. We propose our approach as a ‘best practice’

Cold-adapted culturing of the microalga Monoraphidium sp. in thin-layer raceway pond for biomass production

Three cultivation regimes were tested in cold-adapted cultures of the green microalga Monoraphidium in an outdoor thin-layer raceway pond: cultivation under sunlight; its combination with continuous supplementary illumination; and nitrogen depletion using both light sources. The highest volumetric and areal productivity, 0.16 g L−1 d−1 and 3.22 g m−2 d−1, respectively corresponding to the specific growth rate μ of 0.191 d−1 were achieved when sunlight was combined with supplementary illumination. The maximum total fatty acid content, 20.29 % of DW, rich in oleic acid, 54 % of total fatty acid content, was achieved under nitrogen depletion stress. An outstanding amount of lutein, 26.39 mg lutein g−1 DW, was detected grown under sunlight in the first trial. From the harvested and fermented biomass in the second trial 236 mLN g−1oTS of methane was generated

Gypsum endolithic phototrophs under moderate climate (Southern Sicily): their diversity and pigment composition

In this study, we used microscopic, spectroscopic, and molecular analysis to characterize endolithic colonization in gypsum (selenites and white crystalline gypsum) from several sites in Sicily. Our results showed that the dominant microorganisms in these environments are cyanobacteria, including: Chroococcidiopsis sp., Gloeocapsopsis pleurocapsoides, Gloeocapsa compacta, and Nostoc sp., as well as orange pigmented green microalgae from the Stephanospherinia clade. Single cell and filament sequencing coupled with 16S rRNA amplicon metagenomic profiling provided new insights into the phylogenetic and taxonomic diversity of the endolithic cyanobacteria. These organisms form differently pigmented zones within the gypsum. Our metagenomic profiling also showed differences in the taxonomic composition of endoliths in different gypsum varieties. Raman spectroscopy revealed that carotenoids were the most common pigments present in the samples. Other pigments such as gloeocapsin and scytonemin were also detected in the near-surface areas, suggesting that they play a significant role in the biology of endoliths in this environment. These pigments can be used as biomarkers for basic taxonomic identification, especially in case of cyanobacteria. The findings of this study provide new insights into the diversity and distribution of phototrophic microorganisms and their pigments in gypsum in Southern Sicily. Furthemore, this study highlights the complex nature of endolithic ecosystems and the effects of gypsum varieties on these communities, providing additional information on the general bioreceptivity of these environments.This project was supported by the Czech Science Foundation (Grant/Award No. 17-04270S and 21-03322S), Ministry of Education, Youth and Sports of the Czech Republic, National Programme of Sustainability I (Grant/Award No. LO1416), Charles University (Grant/Award Nos. UNCE/SCI/006 and UNCE 204069), ALGAMIC (Grant/Award No. CZ.1.05/2.1.00/19.0392). JM was supported by the Czech Science Foundation (GAČR) Project No. 22-06374S to accomplish phylogenetic and taxonomic analysis. JW was thankful for the financial support by the PGC2021-124362NB-I00 grant from MCI/AEI (Spain) and FEDER.Peer reviewe

Diatom distributions in space and time – a case study from the polar regions

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日（火） 統計数理研究所 ３階セミナー

Ekosystém jezer ostrova James Ross - krátká charakteristika

We present a short overview of lakes of James Ross Island, their origin, geomorphological and hydrological position, physical, chemical and biological characteristics

Phytoplankton in acidified lakes: structure, function and response to ecosystem recovery

This thesis is based on five publications dealing with plankton assemblages of lakes in two heavily acidified mountain areas in Central Europe, the Bohemian Forest and the High Tatra Mountains. As both lake districts are the object of long term systematic ecological research, a unique set of complex limnological data was gathered, enabling a comparison with other affected regions throughout the world and also some attempts at generalisation. My role in the team consisted chiefly in the study of phytoplankton as the key component of the food web. I was mainly concerned with the structure, seasonal development and function of the phytoplankton assemblages, and I also focused on the evaluation of general biological response to the current chemical recovery of the lakes from acidification. The main questions addressed in this thesis with an emphasis on phytoplankton assemblages are the following: What is the recent progress in chemical and biological recovery of the Bohemian Forest lakes from acidification? What are the key factors and mechanisms influencing species composition and structure of plankton biomass in the Bohemian Forest lakes? What is the role of episodic acidification in shaping both phytoplankton abundance and biomass in a non acidified high mountain seepage lake (Ľadové Lake, High Tatra..