Arctic LTER. freshwater metagenome

The long-term goal of the Arctic LTER research program is to predict the effects of climate change on the Arctic system at catchment and landscape scales through knowledge of the linkages and interactions among ecosystems. The MIRADA program provides a new opportunity to assess the diversity of aquatic microbes at the Arctic LTER site in more depth. Sampling was designed to answer two basic questions about spatial and short-term temporal patterns in microbial diversity. * How do microbial communities vary in winter vs. summer in Toolik Lake, and which taxa of Bacteria, Archaea, and Eukarya characterize these periods? * What are the sources of microbial diversity in surface waters? Specifically, how do riparian soil waters and stream hyporheic zones contribute to diversity in surface waters? Because lakes are the primary reservoirs of planktonic microbes in the Arctic LTER system, we sampled the epilimnion and hypolimnion of Toolik Lake during winter and summer. These samples were collected through the ice in May, 2008 and from a boat in July, 2008. To address questions concerning the importance of sources of diversity on the landscape we sampled (1) the primary inlet to Toolik Lake (Toolik Inlet) that drains more than 70% of the Toolik catchment, (2) hyporheic water below the rocky bed of Toolik Inlet stream, (3) soil water drawn from ~10-20 centimeters below the surface of soils near the bank of Toolik inlet, and (4) water from I-8 Inlet, which is a stream that is not influenced by upstream lakes. Conclusions thus far include: * Tag pyrosequencing results mirror what is seen with DGGE approaches. * Lake Bacteria and Eukarya communities are similar year-round, but distinct taxa dominate in different seasons. * Lakes contain the lowest bacterial diversity * Lake-less streams contain highest bacterial diversity * Dispersal is high across the landscape, and upslope communities inoculate downslope environments. Analysis of these samples will provide new insight into the composition of microbial communities at the Arctic LTER research site, the sources of diversity for surface waters, and into temporal and spatial patterns in microbial diversity.