PT Journal
AU Kiesel, J
   Bienhold, C
   Wenzhöfer, F
   Link, H
TI Variability in Benthic Ecosystem Functioning in Arctic Shelf and Deep-Sea Sediments: Assessments by Benthic Oxygen Uptake Rates and Environmental Drivers
SO Frontiers in Marine Science
PU Frontiers Media SA
DI 10.3389/fmars.2020.00426
WP https://macau.uni-kiel.de/receive/macau_mods_00000711
LA en
DE sediment oxygen uptake; organic matter; central Arctic Ocean; shelf; deep-sea; pan-Arctic; Laptev Sea; Beaufort Sea
SN 2296-7745
AB Remineralization of organic matter at the seafloor is an important ecosystem function, as
it drives carbon and nutrient cycling, supplying nutrients for photosynthetic production,
but also controls carbon burial within the sediment. In the Arctic Ocean, changes
in primary production due to rapid sea-ice decline and thinning affect the export
of organic matter to the seafloor and thus, benthic ecosystem functioning. Due to
the remoteness and difficult accessibility of the Arctic Ocean, we still lack baseline
knowledge about patterns of benthic remineralization rates and their drivers in both
shelf and deep-sea sediments. Particularly comparative studies across regions are
scarce. Here, we address this knowledge gap by contrasting benthic diffusive and
total oxygen uptake rates (DOU and TOU), both established proxies of the benthic
remineralization function, between shelf and deep-sea habitats of the Barents Sea and
the central Arctic Ocean, sampled during a RV Polarstern expedition in 2015. DOU and
TOU were measured using ex situ porewater oxygen microprofiles and sediment core
incubations, respectively. In addition, contextual parameters including organic matter
availability and microbial cell numbers were determined as environmental predictors.
Pan-Arctic regional comparisons were obtained by extending our analyses to previously
published data from the Laptev and Beaufort Seas. Our results show that (1) benthic
oxygen uptake rates and most environmental predictors varied significantly between
shelf and deep-sea habitats; (2) the availability of detrital organic matter is the main
driver for patterns in total as well as diffusive respiration, while bacterial abundances
were highly variable and only a weak predictor of differences in TOU and DOU; (3)
regional differences in oxygen uptake across shelf and deep-sea sediments were mainly
related to organic matter availability and may reflect varying primary production regimes
and distances to the nearest shelf. Our findings suggest that the expected decline in
sea-ice cover and the subsequent increase in export of organic matter to the seafloor
may particularly enhance remineralization in the deep seas of the Arctic Ocean, altering
benthic ecosystem functioning in future climate scenarios.
PI Lausanne
ER