Bacterioplankton and phytoplankton production in a large patagonian reservoir (República Argentina)

Abstract

Relationships between the secondary production of bacterioplankton and the primary production of phytoplankton in the Ezequiel Ramos Mexia Reservoir were examined. Monthly surveys, parallel measurements on consecutive days, and measurements at different times during the same day were undertaken to determine factors that might influence the relationships between the two sets of productivity measurements. The vertical and seasonal distribution of bacterial production appeared to be strongly related to primary production, with temperature as an important component of this trend. The bacterial production in the water column was equivalent to between 2 and 45% of the phytoplankton production over a period of one year. In a diel study, bacterial secondary production rates fluctuated, with maximum values during the night and early morning. There was no temporal coincidence between algal primary production and bacterial secondary production in daily surveys. It was therefore concluded that isolated measurements of productivity reflect events only at the particular time at which they are obtained. The relationship between algae and bacteria is extremely complex and must be carefully evaluated. The nature of the relationship could be underevaluated if the only measurements taken into consideration were made during the daylight period.