MEPS 186:9-18 (1999)  -  doi:10.3354/meps186009

Benthic in situ respiration in the upwelling area off central Chile

Ronnie Nøhr Glud*, Jens Kristian Gundersen**, Ola Holby***

Max Planck Institute for Marine Microbiology, Microsensor Research Group, Celsiusstraße 1, 28359 Bremen, Germany
Present addresses:
*Marine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark. E-mail:
**National Environmental Research Institute, Vejlsøvej 25, 8600 Silkeborg, Denmark
***Högskolan Dalarna, Röda Vägen 3, 78188 Borlänge, Sweden

ABSTRACT: Benthic O2 uptake rates and O2 microprofiles were measured in the upwelling area off central Chile. Measurements were performed both in situ and in the laboratory on recovered sediment cores. Comparison between the 2 data sets confirmed retrieval and handling artifacts inferred from previous studies. Onboard measurements indicated that the effects were mainly associated with core warming during recovery. Fauna mediated O2 uptake was significant even at abyssal depths and generally in situ O2 uptake rates were higher and showed stronger attenuation with water depth than previous measurements performed in the NE Pacific. However, O2 uptake rates and O2 penetration depths were very similar to measurements performed in the SE Atlantic, and the compiled data sets were approximated by simple exponential equations relating the measurements to water depth. By comparing our total O2 in situ uptake rates to simultaneous measurements of primary production (PP) and new production (NP) of the overlying water column, it was calculated that the benthic mineralization accounted for 13 to 66% of the PP and for 28 to 92% of the NP at water depths shallower than 1000 m. At water depths from 1000 to 4000 m, the benthic mineralization equaled 2 to 11% of the PP and 22 to 38% of the NP. The benthic mineralization thereby accounted for a significant turnover of organic material even at the abyssal stations. The presented data add to the limited number of in situ deep sea mineralization measurements from the southern hemisphere.

KEY WORDS: Benthic mineralization · Oxygen · Landers · In situ · Microsensors

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