Microbial mats in hot springs form a dynamic ecosystem and support the growth of diverse communities with broad-ranging metabolic capacity. In this study, we used 16S rRNA gene amplicon sequencing to analyse microbial communities in mat samples from two hot springs in Al Aridhah, Saudi Arabia. Putative metabolic pathways of the microbial communities were identified using phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt). Filamentous anoxygenic phototrophic bacteria associated with phylum Chloroflexi were abundant (> 50 %) in both hot springs at 48 °C. Chloroflexi were mainly represented by taxa Chloroflexus followed by Roseiflexus. Cyanobacteria of genus Arthrospira constituted 3.4 % of microbial mats. Heterotrophic microorganisms were mainly represented by Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes. Archaea were detected at a lower relative abundance (< 1 %). Metabolic pathways associated with membrane transport, carbon fixation, methane metabolism, amino acid biosynthesis, and degradation of aromatic compounds were commonly found in microbial mats of both hot springs. In addition, pathways for production of secondary metabolites and antimicrobial compounds were predicted to be present in microbial mats. In conclusion, microbial communities in the hot springs of Al Aridhah were composed of diverse bacteria, with taxa of Chloroflexus being dominant.
The recently advanced approach of wavelet transforms is applied to the analysis of lake levels. The aim of this study is to investigate the variability of lake levels in four lakes in the Great Lakes region where the method of continuous wavelet transform and global spectra are used. The analysis of lake-level variations in the time-scale domain incorporates the method of continuous wavelet transform and the global spectrum. Four lake levels, Lake Erie, Lake Michigan, Lake Ontario, and Lake Superior in the Great Lakes region were selected for the analysis. Monthly lake level records at selected locations were analyzed by wavelet transform for the period 1919 to 2004. The periodic structures of the Great Lakes levels revealed a spectrum between the 1-year and 43- year scale level. It is found that major lake levels periodicities are generally the annual cycle. Lake Michigan levels show different periodicities from Lake Erie and Lake Superior and Lake Ontario levels. Lake Michigan showed generally long-term (more than 10 years) periodicities. It was shown that the Michigan Lake shows much stronger influences of inter-annual atmospheric variability than the other three lakes. The other result was that some interesting correlations between global spectrums of the lake levels from the same climatic region were found. and Nedávno zdokonalená metóda vlnovej transformácie je aplikovaná na analýzu úrovne hladín jazier. Táto práca obsahuje výsledky štúdia variability úrovne hladín štyroch jazier v regióne Veľkých jazier, s využitím metódy kontinuálnej vlnovej transformácie a globálneho spektra. Boli študované variácie hladín vybraných Veľkých jazier v závislosti od času. Na analýzu úrovne hladín boli vybrané štyri jazerá: Lake Erie, Lake Michigan, Lake Ontario, a Lake Superior v regióne Great Lakes. Mesačné chody úrovne hladín za obdobie rokov 1919 až 2004 boli študované vlnovou analýzou. Periodická štruktúra hladín Great Lakes bola zistená v spektre medzi 1 a 43 rokmi. Bolo zistené, že hlavnou periódou úrovne hladín je ročný cyklus. Na rozdiel od jazier Lake Erie, Lake Superior a Lake Ontario úrovne hladín Lake Michigan majú inú periodicitu. Lake Michigan má vo všeobecnosti dlhodobú (viac ako 10-ročnú) periodicitu. Je ukázané, že jazero Michigan reaguje na medziročnú variabilitu vlastností atmosféry výraznejšie ako ostatné tri jazerá. Ďalšími výsledkami analýzy sú niektoré zaujímavé korelácie medzi všeobecným spektrom úrovne hladín jazier z identického klimatického regiónu.