BASTIDAS NAVARRO marcela Alejandra
Effects of volcanic pumice inputs on microbial community composition and dissolved C:P ratios in lake waters: an experimental approach
MODENUTTI B.; E. BALSEIRO; M. BASTIDAS NAVARRO; Z. LEE; M.S. SOUZA; J. CORMAN; J. ELSER
Lugar: Berlin; Año: 2016 vol. 71 p. 18 - 28
Volcanic eruptions discharge massive amounts of ash and pumice that decrease light penetration in lakes and lead to concomitant increases in phosphorus (P) concentrations and shifts in soluble C:P ratios. The consequences of these sudden changes for bacteria community composition, metabolism and enzymatic activity remain unclear, especially for the dynamic period immediately after pumice deposition. Thus, the main aim of our study was to determine how ambient bacterial communities respond to pumice inputs in lakes that differ in DOC and P concentrations and to what extent these responses are moderated by substrate C:P stoichiometry. We performed an outdoor experiment with natural lake water from two lakes that differed in dissolved organic carbon (DOC) concentration. We measured nutrient concentrations, alkaline phosphatase activity (APA), and DOC consumption rates and assessed different components of bacterial community structure using next-generation sequencing of the 16S rRNA gene. Pumice inputs caused a decrease in the C:P ratio of dissolved resources, a decrease in APA activity, and an increase in DOC consumption, indicating reduced P limitation. These changes in bacteria metabolism were coupled with modifications in the assemblage composition and an increase in diversity, with increases in bacterial taxa associated with biofilm and sediments, in predatory bacteria, and in bacteria with gliding motility.