Jenny Baeseman

Life in the Main Channel: Long-Term Hydrologic Control of Microbial Mat Abundance in McMurdo Dry Valley Streams, Antarctica

Given alterations in global hydrologic regime, we examine the role of hydrology in regulating stream microbial mat abundance in the McMurdo Dry Valleys, Antarctica. Here, perennial mats persist as a desiccated crust until revived by summer streamflow, which varies inter-annually, and has increased since the 1990s. We predicted high flows to scour mats, and intra-seasonal drying to slow growth. Responses were hypothesized to differ based on mat location within streams, along with geomorphology, which may promote (high coverage) or discourage (low coverage) accrual. We compared hydrologic trends with the biomass of green and orange mats, which grow in the channel, and black mats growing at stream margins for 16 diverse stream transects over two decades. We found mat biomass collectively decreased during first decade coinciding with low flows, and increased following elevated discharges. Green mat biomass showed the greatest correlations with hydrology and was stimulated by discharge in high coverage transects, but negatively correlated in low coverage due to habitat scour. In contrast, orange mat biomass was negatively related to flow in high coverage transects, but positively correlated in low coverage because of side-channel expansion. Black mats were weakly correlated with all hydrologic variables regardless of coverage. Lastly, model selection indicated the best combination of predictive hydrologic variables for biomass differed between mat types, but also high and low coverage transects. These results demonstrate the importance of geomorphology and species composition to modeling primary production, and will be useful in predicting ecological responses of benthic habitats to altered hydrologic regimes.

Molecular Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica

Abstract The McMurdo Dry Valleys possess a cold and dry climate which favours biomolecular preservation, and present the possibility for preservation of biological materials over long timescales. We examined patterns of bacterial DNA abundance and diversity in algal mats from 8–26 539 years of age. Bacterial DNA abundance was inferred from extractable DNA quantity and quantitative polymerase chain reaction targeting the bacterial 16S rRNA gene. Because damage to bacterial DNA could limit its availability for polymerase chain reaction, the efficacy of DNA repair by a commercially available kit was also examined. Polymerase chain reaction amplicons of the bacterial 16S rRNA gene were obtained from seven of eight samples. Bulk DNA abundance and bacterial 16S rRNA gene copy number of template DNA declined with increasing sample age consistent with expectations of accumulation of DNA damage in ancient materials. Clone libraries revealed age related patterns of abundance for some bacterial phylogenetic groups. For example, Firmicutes and several other lineages were abundant in ancient samples, but Cyanobacteria were absent. This points to a biased persistence of bacterial lineages that change over time since photosynthesis was active.

Preparing New Polar Researchers to Lead the Next International Polar Year: New Generation of Polar Researchers Symposium; Colorado Springs, Colorado, 4–11 May 2008

Logistics and physical conditions of polar research today, though challenging, are considered comfortable compared with what polar researchers endured 50 years ago during the 1957–1958 International Geophysical Year (IGY). However, the intellectual terrain has grown far more demanding than that of the past. This new generation of polar researchers must not only achieve disciplinary expertise but also be ready to communicate beyond a specialist audience, conduct transformative research, participate in outreach and public communication, keep up with technological and computational developments, and support their research in an increasingly competitive funding environment, all while addressing the urgency of our changing planet.

Professional Development Training for Early Career Polar Researchers: Association of Polar Early Career Scientists Career Development Workshop; St. Petersburg, Russia, 7 July 2008

One hundred early career researchers working in a range of disciplines met in Russia on 7 July for a career development workshop targeting polar researchers. The workshop was hosted by the Association of Polar Early Career Scientists (APECS) in collaboration with the Scientific Committee on Antarctic Research (SCAR) and the International Arctic Science Committee (IASC) as part of the SCAR/IASC Open Science Conference “Polar Research—Arctic and Antarctic Perspectives in the International Polar Year.” Demands on early career researchers are increasing. They not only need to excel academically but must also compete for funding with well-established researchers, foster collaborations, and communicate their research to a diverse audience of colleagues, peers, and funding agencies within and outside of their own disciplines and countries. Representatives from funding agencies and research councils including the U.S. National Science Foundation (NSF), the U.K. Natural Environment Research Council (NERC), Antarctica New Zealand, IASC, and SCAR ran sessions and panel discussions focusing on key skills in writing proposals, conducting remote and logistically complex fieldwork, communicating their science, and improving research productivity. Through this, early career researchers had the unique opportunity to question potential reviewers and employers about how best to succeed in polar science.