caa a22 4500 605517614 CHVBK 20210128100720.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s10533-015-0113-4 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0113-4 Effects of experimental warming and carbon addition on nitrate reduction and respiration in coastal sediments [Elektronische Daten] [Lindsay Brin, Anne Giblin, Jeremy Rich] Climate change may have differing effects on microbial processes that control coastal N availability. We conducted a microcosm experiment to explore effects of warming and carbon availability on nitrate reduction pathways in marine sediments. Sieved continental shelf sediments were incubated for 12weeks under aerated seawater amended with nitrate (~50μM), at winter (4°C) or summer (17°C) temperatures, with or without biweekly particulate organic C additions. Treatments increased diffusive oxygen consumption as expected, with somewhat higher effects of C addition compared to warming. Combined warming and C addition had the strongest effect on nitrate flux across the sediment water interface, with a complete switch early in the experiment from influx to sustained efflux. Supporting this result, vial incubations with added 15N-nitrate indicated that C addition stimulated potential rates of dissimilatory nitrate reduction to ammonium (DNRA), but not denitrification. Overall capacity for both denitrification and DNRA was reduced in warmed treatments, possibly reflecting C losses due to increased respiration with warming. Anammox potential rates were much lower than DNRA or denitrification, and were slightly negatively affected by warming or C addition. Overall, results indicate that warming and C addition increased ammonium production through remineralization and possibly DNRA. This stimulated nitrate production through nitrification, but without a comparable increase in nitrate consumption through denitrification. The response to C of potential DNRA rates over denitrification, along with a switch to nitrate efflux, raises the possibility that DNRA is an important and previously overlooked source of internal N cycling in shelf sediments. Springer International Publishing Switzerland, 2015 Anammox nationallicence Climate change nationallicence Continental shelf nationallicence Denitrification nationallicence Dissimilatory nitrate reduction to ammonium nationallicence Warming nationallicence Brin Lindsay Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, 02912, Providence, RI, USA aut Giblin Anne Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, 02543, Woods Hole, MA, USA aut Rich Jeremy Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, 02912, Providence, RI, USA aut Biogeochemistry Springer International Publishing 125/1(2015-08-01), 81-95 0168-2563 125:1<81 2015 125 10533 https://doi.org/10.1007/s10533-015-0113-4 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0113-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Brin Lindsay Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, 02912, Providence, RI, USA aut NATIONALLICENCE 700 1- Giblin Anne Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, 02543, Woods Hole, MA, USA aut NATIONALLICENCE 700 1- Rich Jeremy Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, 02912, Providence, RI, USA aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 125/1(2015-08-01), 81-95 0168-2563 125:1<81 2015 125 10533