Effects of Volcanic Pumice Inputs on Microbial Community Composition and Dissolved C/P Ratios in Lake Waters: an Experimental Approach

MODENUTTI, B.; LEE, Z.; ELSER, J.; BALSEIRO, E.; SOUZA, M.S.; BASTIDAS NAVARRO, M.; CORMAN, J.

MICROBIAL ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2016 vol. 71 p. 18 - 28

0095-3628

Abstract Volcanic eruptions discharge massive amounts of ashand pumice that decrease light penetration in lakes and lead toconcomitant increases in phosphorus (P) concentrations andshifts in soluble C/P ratios. The consequences of these suddenchanges for bacteria community composition, metabolism, andenzymatic activity remain unclear, especially for the dynamicperiod immediately after pumice deposition. Thus, the mainaim of our study was to determine how ambient bacterial communitiesrespond to pumice inputs in lakes that differ in dissolvedorganic carbon (DOC) and P concentrations and to what extentthese responses are moderated by substrate C/P stoichiometry.We performed an outdoor experiment with natural lake waterfrom two lakes that differed in dissolved organic carbon (DOC)concentration. We measured nutrient concentrations, alkalinephosphatase activity (APA), and DOC consumption rates andassessed different components of bacterial community structureusing next-generation sequencing of the 16S rRNA gene. Pumiceinputs caused a decrease in the C/P ratio of dissolved resources,a decrease in APA, and an increase in DOC consumption,indicating reduced P limitation. These changes in bacteriametabolism were coupled with modifications in the assemblagecomposition and an increase in diversity, with increases in bacterialtaxa associated with biofilm and sediments, in predatorybacteria, and in bacteria with gliding motility. Our results confirmthat volcanic eruptions have the potential to alter nutrientpartitioning and light penetration in receiving waterways whichcan have dramatic impacts on microbial community dynamics.