Abstract
Over 1 million km2 of seafloor experience permanent low-oxygen
conditions within oxygen minimum zones (OMZs). OMZs are predicted to
grow as a consequence of climate change, potentially affecting oceanic
biogeochemical cycles. The Arabian Sea OMZ impinges upon the western
Indian continental margin at bathyal depths (150 - 1500 m) producing a
strong depth dependent oxygen gradient at the sea floor. The influence
of the OMZ upon the short term processing of organic matter by sediment
ecosystems was investigated using in situ stable isotope pulse chase
experiments. These deployed doses of 13C:15N labeled organic matter onto
the sediment surface at four stations from across the OMZ (water depth
540 - 1100 m; [O2] = 0.35 - 15 μM). In order to prevent
experimentally anoxia, the mesocosms were not sealed. 13C and 15N labels
were traced into sediment, bacteria, fauna and 13C into sediment
porewater DIC and DOC. However, the DIC and DOC flux to the water column
could not be measured, limiting our capacity to obtain mass-balance for
C in each experimental mesocosm. Linear Inverse Modeling (LIM)
provides a method to obtain a mass-balanced model of carbon flow that
integrates stable-isotope tracer data with community biomass and
biogeochemical flux data from a range of sources. Here we present an
adaptation of the LIM methodology used to investigate how ecosystem
structure influenced carbon flow across the Indian margin OMZ. We
demonstrate how oxygen conditions affect food-web complexity, affecting
the linkages between the bacteria, foraminifera and metazoan fauna, and
their contributions to benthic respiration. The food-web models
demonstrate how changes in ecosystem complexity are associated with
oxygen availability across the OMZ and allow us to obtain a complete
carbon budget for the stationa where stable-isotope labelling
experiments were conducted.
Original language | English |
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Publication status | Published - 2013 |
Event | European Geoscience Union 2013 - Vienna, Austria Duration: 07 Apr 2013 → 13 Apr 2013 |
Conference
Conference | European Geoscience Union 2013 |
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Country/Territory | Austria |
City | Vienna |
Period | 07/04/2013 → 13/04/2013 |