Browsing by Author "Anesio, Alexandre M."

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Carbon fluxes through bacterial communities on glacier surfaces
(2010-12) Anesio, Alexandre M.; Sattler, Birgit; Foreman, Christine M.; Telling, Jon; Hodson, Andy; Tranter, Martyn; Psenner, Roland
There is very little information about the activity of microbial communities on the surfaceof glaciers, though there is an increasing body of evidence to show that they strongly influence the biogeochemistry of these habitats. We measured bacterial abundance and production in cryoconite holes on Arctic, Antarctic and Alpine glaciers in order to estimate the role of heterotrophic bacteria within the carbon budget of glacial ecosystems. Our results demonstrate an active bacterial community on the surface of glaciers with doubling times that vary from a few hours to hundreds of days depending on the glacier and position (water or sediments) within the cryoconite hole. However, bacterial production is only ~2â€“3% of the published literature values of community respiration from similar habitats, indicating that other types of microbes (e.g. eukaryotic organisms) may also play a role in the C cycle of glaciers. We estimate that only up to 7% of the organic C in cryoconite sediments is utilized by the heterotrophic bacterial community annually, suggesting that the surface of glaciers can accumulate organic carbon, and that this C may be important for biogeochemical activity downstream to adjacent ecosystems.
Planetary Protection and Mars Special Regions—A Suggestion for Updating the Definition
(2016-02) Rettberg, Petra; Anesio, Alexandre M.; Baker, Victor R.; Baross, Victor R.; Cady, Sherry L.; Detsis, Emmanouil; Foreman, Christine M.; Hauber, Ernst; Ori, Gian G.; Pearce, David A.; Renno, Nilton O.; Ruvkun, Gary; Sattler, Birgit; Saunders, Mark P.; Smith, David H.; Wagner, Dirk; Westall, Frances
We highlight the role of COSPAR and the scientific community in defining and updating the framework of planetary protection. Specifically, we focus on Mars “Special Regions,” areas where strict planetary protection measures have to be applied before a spacecraft can explore them, given the existence of environmental conditions that may be conducive to terrestrial microbial growth. We outline the history of the concept of Special Regions and inform on recent developments regarding the COSPAR policy, namely, the MEPAG SR-SAG2 review and the Academies and ESF joint committee report on Mars Special Regions. We present some new issues that necessitate the update of the current policy and provide suggestions for new definitions of Special Regions. We conclude with the current major scientific questions that remain unanswered regarding Mars Special Regions. Key Words: Planetary protection—Mars Special Regions—COSPAR policy. Astrobiology 16, 119–125.