Life on floating pumice

ELSER, J.; J. CORMAN; Z. LEE; J. SIEFERT; M. BASTIDAS NAVARRO; F. CUASSOLO; C. LASPOUMADERES; M.S. SOUZA; E. BALSEIRO; B. MODENUTTI

Congreso; ASLO Aquatic Sciences Meeting; 2012

One 4 June 2011 a mega-eruption occurred in the Puyehue-Cordón Caulle Volcanic Complex (Chile), ejecting massive amounts of ash and pumice into the surrounding region, especially to the east and southeast near Bariloche, Argentina. Indeed, the pumice formed massive rafts in Lake Nahuel Huapi and other lakes that were visible from satellite. This floating pumice provides unique, initially sterile, substrates that should be colonized by microbes over time. Which taxa of microbes colonize these novel habitats and how do these communities change over time? How do biota cope with environmental conditions and acquire nutrients for proliferation on the pumice? We sampled pumice in these lakes from July 2011 until March 2012, preserving samples for determination of microbial community composition (via DNA barcoding approaches based on IonTorrent technology). Samples were taken in several of the lakes at approximately monthly intervals for comparison of successional changes and assessment of the similarity of the communities in different lakes. We also assessed nutrient (inorganic N and P) use via changes in bulk PO4 and NH4 concentrations and via 15N-labeled NH4 and NO3 and 18O-labeled PO4. We also prepared isotopically labeled samples for visualization of nutrient utilization using Nano-SIMS. This talk will involve a guided tour through the pumice-impacted zone and present preliminary data from these ongoing field studies.