Distributions and fates of oxygen in periphyton communities

Abstract

Direct measurements with oxygen microelectrodes demonstrated that the distribution of dissolved oxygen in periphyton communities varied on a diurnal basis and was markedly different among periphyton types. During illumination, photosynthesis in periphyton resulted in oxygen supersaturation in microzones that were subsaturated or anoxic during darkness. The fate of oxygen produced within periphyton depended on the relative rates of production and consumption, the diffusion characteristics of the periphyton, physical and chemical interactions with the substratum, and the transport rate across the boundary layer, which was affected significantly by water currents. During constant environmental conditions, steady-state oxygen distributions occurred within periphyton, but equilibrium with the surrounding water was rare.