Enigmatic Marine Ecosystem Metabolism Measured by Direct Diel ΣCO2 and O2 Flux in Conjunction with DOC Release and Uptake

Authors

Kenneth M. Johnson, University of Rhode Island
Curtis M. Burney, University of Rhode IslandFollow
John McN. Sieburth, University of Rhode Island

Document Type

Article

Publication Title

Marine Biology

ISSN

0025-3162

Publication Date

11-1981

Abstract

In an attempt to evaluate ΣCO₂ changes as an index of net ecosystem metabolism, ΣCO₂ and dissolved organic carbon (DOC) by infrared (IR) analysis and O₂ by the Winkler method were followed over 12 diel cycles in a salt marsh, a simulated estuarine ecosystem, and the mixed layer of the northwestern Caribbean Sea. Each ecosystem exhibited replicable diel cycles, net production during the photoperiod, and a significant inverse correlation between ΣCO₂ and O₂ changes. Daily rates of system production and respiration calculated from ΣCO₂, however, exceeded those from O₂ by 1.5 to 3.5 fold in nearshore waters and by 2 to 6 fold in the open ocean. Net total system apparent production based on O₂ and ΣCO₂, respectively, were 2 345 and 3 604 mg C m^-3d^-1 for the salt marsh, 348 and 625 mg C m^-3d^-1 for the estuarine ecosystem, and 53 and 306 mg C m^-3d^-1 for the oceanic ecosystem, both parameters exceeding 14C data in the literature for similar environments by one to two orders of magnitude. The IR ΣCO₂ productivity estimates are compatible with the diel cycles in DOC. In the marsh and Caribbean Sea, maxinium DOC concentrations were usually observed in the evening following a gradual accumulation during the photoperiod, while minimal values occurred in the early morning. In all ecosystems the average net release of DOC lagged CO₂ uptake and O₂ production and represented 22.7 and 43.3% of the carbon fixed as estimated from CO₂ uptake and O₂ production, respectively. If the consistently higher ΣCO2 measurements are not a systematic error nor due to atmospheric diffusion, then diel variation in O₂ and CO₂ may not always be quantitatively coupled due in part to habitat-dependent factors such as the nonphotosynthetic incorporation of CO₂ and chemosynthetic removal of O₂.

DOI

10.1007/BF00397067

Volume

65

Issue

1

First Page

49

Last Page

60

Comments

©Springer-Verlag 1981

Additional Comments

NSF grant #s:OCE-7681779, OCE-7826388; EPA Grant:R-80-607-202

NSUWorks Citation

Kenneth M. Johnson, Curtis M. Burney, and John McN. Sieburth. 1981. Enigmatic Marine Ecosystem Metabolism Measured by Direct Diel ΣCO2 and O2 Flux in Conjunction with DOC Release and Uptake .Marine Biology , (1) : 49 -60. https://nsuworks.nova.edu/occ_facarticles/637.