Microbial respiration in the euphotic zone at Station ALOHA

• Measurements of the temporal and vertical variability of microbial community respiration (MCR) in the euphotic zone (0-200m) at Station ALOHA were made using the in vivo INT method to constrain oxygen and carbon cycling at this oceanic site. Mean (+/- 1 SE) MCR was higher in the upper (0-100m) (0.89 +/- 0.05mmol O-2 m(-3) d(-1)) than in the lower (100-200 m) portion of the euphotic zone (0.52 +/- 0.05mmol O-2 m(-3) d(-1)). Respiration in the 0.8 mu m size-fraction relative to respiration in the 0.2-0.8 mu m size-fraction was on average 1.4 +/- 0.1. Variability in MCR was observed on both daily and monthly time scales, suggesting that respiration is a dynamic process throughout the year at Station ALOHA. MCR in the 0.2-0.8 mu m size fraction was more variable than >0.8 mu m MCR. Despite significant vertical and temporal variability in MCR, the euphotic zone depth-integrated (0-200m) MCR was relatively constant (134.8 +/- 11.8 mmol O-2 m(-2) d(-1)) throughout the period of observation. Oxygen consumption via MCR always exceeded O-2 production extrapolated from C-14-primary production estimation, assuming a photosynthetic quotient of 1.13mol O-2 produced : mol CO2 fixed. MCR plus particulate carbon export from the euphotic zone for the period November 2011-October 2012 at Station ALOHA can be used to set a lower limit of similar to 45mol C m(-2) yr(-1) for gross primary production.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Akvatisk ekologi

Aquatic Ecology

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