High dark inorganic carbon fixation rates by specific microbial groups in the Atlantic off the Galician coast (NW Iberian margin)

Author(s)
Elisa Guerrero-Feijoo, Eva Sintes, Gerhard J. Herndl, Marta M. Varela
Abstract

Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production throughout the water column, however, more prominently in the bathypelagic waters. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) allowed us to identify several microbial groups involved in dark DIC uptake. The contribution of SAR406 (Marinimicrobia), SAR324 (Deltaproteobacteria) and Alteromonas (Gammaproteobacteria) to the dark DIC fixation was significantly higher than that of SAR202 (Chloroflexi) and Thaumarchaeota, in agreement with their contribution to microbial abundance. Q-PCR on the gene encoding for the ammonia monooxygenase subunit A (amoA) from the putatively high versus low ammonia concentration ecotypes revealed their depth-stratified distribution pattern. Taken together, our results indicate that chemoautotrophy is widespread among microbes in the dark ocean, particularly in bathypelagic waters. This chemolithoautotrophic biomass production in the dark ocean, depleted in bio-available organic matter, might play a substantial role in sustaining the dark ocean's food web.

Organisation(s)
Functional and Evolutionary Ecology
External organisation(s)
IEO - Centro Oceanográfico A Coruña, Royal Netherlands Institute for Sea Research, Utrecht University
Journal
Environmental Microbiology
Volume
20
Pages
602-611
No. of pages
10
ISSN
1462-2912
DOI
https://doi.org/10.1111/1462-2920.13984
Publication date
02-2018
Peer reviewed
Yes
Austrian Fields of Science 2012
Marine biology
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/high-dark-inorganic-carbon-fixation-rates-by-specific-microbial-groups-in-the-atlantic-off-the-galician-coast-nw-iberian-margin(d69a5c2d-a135-4bea-bb13-d2149de74cb1).html