Periphyton and Endolith Targeted Locus (Loci). hot springs metagenome

16S rDNA from aquatic and terrestrial samples from Troll Springs. A critical question in microbial ecology concerns how environmental conditions affect community makeup. Arctic thermal springs provide an opportunity to study this question due to steep environmental gradients that impose strong selective pressures. We use microscopic and molecular methods to study microbial community makeup at Troll Springs on Svalbard in the high Arctic. Microorganisms there exist under a wide range of environmental conditions: in warm water as periphyton, in moist granular materials, and in cold, dry rock as endoliths. Troll Springs therefore has two distinct ecosystems, aquatic and terrestrial, together in close proximity, with different underlying environmental factors shaping their microbial communities. Environmental gradients are steep, with major changes over just tens of meters, minimizing the effects of environmental parameters that vary over larger scales. Periphyton are entrapped during precipitation of calcium carbonate from the spring’s waters, becoming a precursor for endolithic communities. This differs from most endolith colonization, where rock predates the communities that colonize it. Community makeup is modulated as environmental conditions change.