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Seasonal and spatial patterns of oxygen production, respiration and root-rhizome release in Potamogeton perfoliatus L. and Zostera marina L.
Journal article   Peer reviewed

Seasonal and spatial patterns of oxygen production, respiration and root-rhizome release in Potamogeton perfoliatus L. and Zostera marina L.

J. M. Caffrey and W. M. Kemp
Aquatic Botany, Vol.40, pp.109-128
40
1991
DOI: https://doi.org/10.1016/0304-3770(91)90090-R
Web of Science ID: WOS:A1991FP89900002

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Abstract

Oxygen release to the rhizosphere was measured in situ with O₂ microelectrodes and in hydroponic, split-compartment chambers. Light-dark experiments revealed that O₂ release from the rhizomes of Potamogeton perfoliatus L. was directly dependent on photosynthesis and that O₂ concentrations in sediments near the rhizomes started to decrease within 2 min after plants were darkened. Using Fick's first law of diffusion, the calculated net O₂ flux in P. perfoliatus was approximately 120 μmol g⁻¹ dry weight h⁻¹, similar to fluxes calculated from hydroponic measurements. Root-rhizome O₂ release, photosynthesis and respiration were measured for P. perfoliatus and Zostera marina L., with split-compartment hydroponic chambers in spring, summer and fall. For Z. marina, variability of root-rhizome O₂ release, photosynthesis and respiration were observed between different sites within an eelgrass bed. The highest rates of O₂ release from roots and rhizomes occurred in spring for both species and declined during the summer. For P. perfoliatus, the shortest plants (< 10 cm stem length) had the highest O₂ release, about 43 μmol g⁻¹ dry weight h⁻¹. Root-rhizome O₂ release was significantly related to photosynthesis only for P. perfoliatus. Oxidation of the rhizosphere depended on root-rhizome O₂ release and biomass, which changed seasonally. Although weight-specific release rates were higher for P. perfoliatus than Z. marina, the potential oxidation of the rhizosphere was similar for both species (approximately 4–6 mmol O₂ m⁻² h⁻¹) because of relatively high Z. marina root and rhizome biomass.

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