Thursday, October 29, 2009, 4:30PM - 5:30PM
Full title: "Spatial variation in benthic diatom community composition in Antarctic stream ecosystems."
Stream microbial mats are dynamic communities of photosynthetic and heterotrophic organisms. Diatom communities in microbial mats are influenced by successional processes and scouring events that together act to shape stream benthic habitats. In ephemeral streams of the McMurdo Dry Valleys (MDV, Antarctica), previous work has demonstrated that in streams within the MDV, the diatom composition in is determined largely by the annual and historical flow regime. This study found that the relative abundances of endemic diatom species increases under a colder, lower stream flow regime. Conversely, warmer, higher-flow conditions favor widespread diatom species, and concomitant decreases in diatom species diversity occur at either extreme. However, we still do not understand the spatial variation of diatom communities within a stream reach or how much communities vary from stream to stream. This is important because diatoms are often used as ecological indicators and we don’t yet understand enough about spatial variability of Antarctic diatom species to correlate diatom community changes to environmental changes, despite previous efforts. This study aims to define these spatial variations in microbial mats within and across two Dry Valley streams. Environmental factors, particularly stream flow, are currently being modeled in order to identify drivers of community composition. Results show that there are significant differences between diatom communities within and across streams, indicating the importance of considering spatial scale in diatom monitoring projects even in “harsh” environments.