@article{D'HondtSpivackPockalnyetal.2009, author = {D'Hondt, Steven and Spivack, Arthur J. and Pockalny, Robert and Ferdelman, Timothy G. and Fischer, Jan P. and Kallmeyer, Jens and Abrams, Lewis J. and Smith, David C. and Graham, Dennis and Hasiuk, Franciszek and Schrum, Heather and Stancin, Andrea M.}, title = {Subseafloor sedimentary life in the South Pacific Gyre}, issn = {0027-8424}, doi = {10.1073/pnas.0811793106}, year = {2009}, abstract = {The low-productivity South Pacific Gyre (SPG) is Earth's largest oceanic province. Its sediment accumulates extraordinarily slowly (0.1-1 m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H-2 by radiolysis of water is a significant electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in oxidation/reduction equivalents) than in previously explored anaerobic subseafloor communities. Respiration rates and cell concentrations in subseafloor sediment throughout almost half of the world ocean may approach those in SPG sediment.}, language = {en} } @article{KallmeyerPockalnyD'Hondt2009, author = {Kallmeyer, Jens and Pockalny, Rob and D'Hondt, Steven}, title = {Quantifying global subseafloor microbial abundance : method and implications}, issn = {0016-7037}, doi = {10.1016/j.gca.2009.05.009}, year = {2009}, language = {en} } @article{RoyKallmeyerAdhikarietal.2012, author = {Roy, Hans and Kallmeyer, Jens and Adhikari, Rishi Ram and Pockalny, Robert and Jorgensen, Bo Barker and D'Hondt, Steven}, title = {Aerobic microbial respiration in 86-million-year-old deep-sea red clay}, series = {Science}, volume = {336}, journal = {Science}, number = {6083}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.1219424}, pages = {922 -- 925}, year = {2012}, abstract = {Microbial communities can subsist at depth in marine sediments without fresh supply of organic matter for millions of years. At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor. We found that the oxygen respiration rates dropped from 10 micromoles of O-2 liter(-1) year(-1) near the sediment-water interface to 0.001 micromoles of O-2 liter(-1) year(-1) at 30-meter depth within 86 million-year-old sediment. The cell-specific respiration rate decreased with depth but stabilized at around 10(-3) femtomoles of O-2 cell(-1) day(-1) 10 meters below the seafloor. This result indicated that the community size is controlled by the rate of carbon oxidation and thereby by the low available energy flux.}, language = {en} } @article{KallmeyerPockalnyAdhikarietal.2012, author = {Kallmeyer, Jens and Pockalny, Robert and Adhikari, Rishi Ram and Smith, David C. and D'Hondt, Steven}, title = {Global distribution of microbial abundance and biomass in subseafloor sediment}, series = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {109}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {40}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.1203849109}, pages = {16213 -- 16216}, year = {2012}, abstract = {The global geographic distribution of subseafloor sedimentary microbes and the cause(s) of that distribution are largely unexplored. Here, we show that total microbial cell abundance in subseafloor sediment varies between sites by ca. five orders of magnitude. This variation is strongly correlated with mean sedimentation rate and distance from land. Based on these correlations, we estimate global subseafloor sedimentary microbial abundance to be 2.9 center dot 10(29) cells [corresponding to 4.1 petagram (Pg) C and similar to 0.6\% of Earth's total living biomass]. This estimate of subseafloor sedimentary microbial abundance is roughly equal to previous estimates of total microbial abundance in seawater and total microbial abundance in soil. It is much lower than previous estimates of subseafloor sedimentary microbial abundance. In consequence, we estimate Earth's total number of microbes and total living biomass to be, respectively, 50-78\% and 10-45\% lower than previous estimates.}, language = {en} } @misc{AdhikariGlombitzaNickeletal.2016, author = {Adhikari, Rishi Ram and Glombitza, Clemens and Nickel, Julia C. and Anderson, Chloe H. and Dunlea, Ann G. and Spivack, Arthur J. and Murray, Richard W. and D'Hondt, Steven and Kallmeyer, Jens}, title = {Hydrogen utilization potential in subsurface sediments}, series = {Frontiers in microbiology}, journal = {Frontiers in microbiology}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407678}, pages = {16}, year = {2016}, abstract = {Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H(2)ases to successively higher concentrations of H-2 in successively deeper zones.}, language = {en} } @article{RadchukReedTeplitskyetal.2019, author = {Radchuk, Viktoriia and Reed, Thomas and Teplitsky, Celine and van de Pol, Martijn and Charmantier, Anne and Hassall, Christopher and Adamik, Peter and Adriaensen, Frank and Ahola, Markus P. and Arcese, Peter and Miguel Aviles, Jesus and Balbontin, Javier and Berg, Karl S. and Borras, Antoni and Burthe, Sarah and Clobert, Jean and Dehnhard, Nina and de Lope, Florentino and Dhondt, Andre A. and Dingemanse, Niels J. and Doi, Hideyuki and Eeva, Tapio and Fickel, J{\"o}rns and Filella, Iolanda and Fossoy, Frode and Goodenough, Anne E. and Hall, Stephen J. G. and Hansson, Bengt and Harris, Michael and Hasselquist, Dennis and Hickler, Thomas and Jasmin Radha, Jasmin and Kharouba, Heather and Gabriel Martinez, Juan and Mihoub, Jean-Baptiste and Mills, James A. and Molina-Morales, Mercedes and Moksnes, Arne and Ozgul, Arpat and Parejo, Deseada and Pilard, Philippe and Poisbleau, Maud and Rousset, Francois and R{\"o}del, Mark-Oliver and Scott, David and Carlos Senar, Juan and Stefanescu, Constanti and Stokke, Bard G. and Kusano, Tamotsu and Tarka, Maja and Tarwater, Corey E. and Thonicke, Kirsten and Thorley, Jack and Wilting, Andreas and Tryjanowski, Piotr and Merila, Juha and Sheldon, Ben C. and Moller, Anders Pape and Matthysen, Erik and Janzen, Fredric and Dobson, F. Stephen and Visser, Marcel E. and Beissinger, Steven R. and Courtiol, Alexandre and Kramer-Schadt, Stephanie}, title = {Adaptive responses of animals to climate change are most likely insufficient}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/s41467-019-10924-4}, pages = {14}, year = {2019}, abstract = {Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.}, language = {en} }