GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 31-8
Presentation Time: 3:40 PM


SPILDE, Michael N.1, NORTHUP, Diana E.2, CAIMI, Nicole A.2, BOSTON, Penelope J.3, STONE, Frederick D.4 and SMITH, Stephen5, (1)Institute of Meteoritics, University of New Mexico, MSC03-2050, Albuquerque, NM 87131, (2)Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131, (3)NASA Astrobiology Institute, NASA Ames Research Center, Moffett Field, CA 94035, (4)Natural Sciences Department, University of Hawaii at Hilo, Hilo, HI 96720, (5)Hawaii Speleological Survey, Hilo, HI 96720,

Microbial mats are a prominent feature in many Hawaiian lava caves, but little research has been done on these communities. Since 2008, we have sampled the microbial communities in16 lava caves on the Big Island of Hawai`i to conduct scanning electron microscopy (SEM) analysis, cultivation, and DNA sequencing. These caves occurred in areas of Hawai`i that varied in rainfall from 47 to 400 cm per year and in flows that ranged in age from thousands of years to less than 100. Sampled communities included microbial mats of various colors from white to tan, yellow, and orange; white mats floating on puddles in the floor; butterscotch-colored organic ooze present in some caves on the walls or ceilings; and a blue-green lava stalactite from a single cave. We also sampled apparent microbial mineral deposits to determine whether deposits contained substantial microorganisms. SEM studies revealed diverse morphologies across the lava caves, with coccoid and filamentous shapes predominating in the microbial mats. The blue-green stalactite exhibited unusual reticulated filaments that have been observed in a few other caves in New Mexico and Germany. Culture media inoculated with microbial mat or mineral deposits on site in the lava caves revealed morphologies consistent with Actinobacteria, and many cultures demonstrated the presence of fugitive dyes that were aqueously soluble. DNA analysis revealed that the white wall microbial mats differed from the yellow, pink, and orange mats, which were similar to each other; Actinobacteria dominated the latter deposits. Overall, the sample types (mat versus mineral versus surface soil) demonstrated significant phylogenic differences, and little overlap between high and low precipitation regimes.