Periphytic primary production during spring. A sink or source of oxygen in the littoral zone?

AbstractThe vertical distribution of gross primary production rates of periphyton communities was determined based on changes in the oxygen concentration. The gross primary production conformed to the colonization pattern of the epiphytic algae on submerged shoots of Phragmites australis. The algae produced the most on stem sections that grew from 0.2 to 0.5 m deep in the littoral zone. The PB rates, however, decreased on these middle sections of the stems due to increasing self-shading by the periphyton. Although high gross oxygen production rates were determined during the hours of incubation, an oxygen deficit was calculated for the full 24 hours periods on all days of the investigations at the time the algae peaks occurred during the spring