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Effects of sinking velocities and microbial respiration rates on the attenuation of particulate carbon fluxes through the mesopelagic zone


McDonnell, AMP and Boyd, PW and Buesseler, KO, Effects of sinking velocities and microbial respiration rates on the attenuation of particulate carbon fluxes through the mesopelagic zone, Global Biogeochemical Cycles, 29, (2) pp. 175-193. ISSN 0886-6236 (2015) [Refereed Article]


Copyright Statement

Copyright 2015 American Geophysical Union

DOI: doi:10.1002/2014GB004935


The attenuation of sinking particle fluxes through the mesopelagic zone is an important process that controls the sequestration of carbon and the distribution of other elements throughout the oceans. Case studies at two contrasting sites, the oligotrophic regime of the Bermuda Atlantic Time-series Study (BATS) and the mesotrophic waters of the west Antarctic Peninsula (WAP) sector of the Southern Ocean, revealed large differences in the rates of particle-attached microbial respiration and the average sinking velocities of marine particles, two parameters that affect the transfer efficiency of particulate matter from the base of the euphotic zone into the deep ocean. Rapid average sinking velocities of 270  150 m d−1 were observed along the WAP, whereas the average velocity was 49  25 m d−1 at the BATS site. Respiration rates of particle-attached microbes were measured using novel RESPIRE (REspiration of Sinking Particles In the subsuRface ocEan) sediment traps that first intercepts sinking particles then incubates them in situ. RESPIRE experiments yielded flux-normalized respiration rates of 0.4  0.1 day−1 at BATS when excluding an outlier of 1.52 day−1, while these rates were undetectable along the WAP (0.01  0.02 day−1). At BATS, flux-normalized respiration rates decreased exponentially with respect to depth below the euphotic zone with a 75% reduction between the 150 and 500 m depths. These findings provide quantitative and mechanistic insights into the processes that control the transfer efficiency of particle flux through the mesopelagic and its variability throughout the global oceans.

Item Details

Item Type:Refereed Article
Keywords:microbial respiration, particle sinking velocity, respiration rates, biological pump, Southern Ocean
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Boyd, PW (Professor Philip Boyd)
ID Code:107026
Year Published:2015
Web of Science® Times Cited:52
Deposited By:IMAS Research and Education Centre
Deposited On:2016-03-02
Last Modified:2017-11-01
Downloads:177 View Download Statistics

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