Ecology of Alkaline Hot Springs: Measuring Diversity and Structure of Chemosynthetic Communities

To date, many phylogenetic diversity studies have been conducted in Yellowstone National Park (YNP) focusing on the amplification of the 16S rRNA gene and “metagenomic” datasets. Few reports focus on diversity at small scales. This study investigates small and intermediate scale biodiversity of sediment and biofilm communities within a confined area of a YNP hot spring, and compares and contrasts these communities to others throughout the park. Sediment and biofilm samples were collected, using a 30 x 50 cm sampling grid divided in 5 x 5 cm squares, which was placed in the outflow channel of Bat Pool, an alkaline (pH 7.9) hot spring in YNP. Additional samples were taken along the outflow channel to determine intermediate scale biodiversity. Accompanying geochemical data included a full range of spectrophotometry measurements along with major ions, trace elements, and DIC/DOC. In addition, in situ temperature and conductivity arrays were placed within the grid location. Biodiversity was analyzed by selecting a representative number of samples from within the grid and along the outflow channel. DNA was extracted and sequenced using 454 pyrotag sequencing or the Illumina HiSeq platform. Analysis was conducted using the software package QIIME (Quantitative Insights Into Microbial Ecology) which afforded taxonomic abundance along with alpha and beta diversity indices. At small spatial scales, within the sampling grid, there is little variation in Archaea, regardless of sample type or sequencing method. There is a great deal of observed variation in Bacteria, regardless of sample type or sequencing method. Position in sampling grid did not correlate with community variation. At intermediate spatial scales, along the outflow channel, no particular pattern is observed in archaeal community structure regardless of sample type, but there are clear downstream trends in the bacterial community, with taxa switching to those that prefer slightly cooler temperatures downstream. At multi-basin scales there does not seem to be an obvious pattern in community structure that is basin-specific. There is substantial variation in these SBCs relative to those at Bat Pool. Overall, there is greater diversity in the bacterial communities than the archaeal communities; sediment and SBC communities differ from each other.