Zooplankton induced decrease in inorganic phosphorus uptake by plankton in an oligotrophic lake

Samples collected from Flathead lake, Montana, showed excretion rates of phosphates by single Daphnia thorata below detection levels (5 pmol per animal.minute) in 20 ml of lake water over 10 minutes. When D. thorata was added to lake water, communitywide microbial uptake of phosphates were reduced on 2 occasions. However, D. thorata increased uptake of organisms less than 1 um and decreased uptake by large phytoplankton.