Life strategy and phosphorus relations of the cyanobacterium Gloeotrichia echinulata in an oligotrophic Precambrian Shield lake

Experiments to measure phosphorus uptake by the cyanobacterium Gloeotrichia echinulata (J. E. SMITH) RICHTER from lake sediments and from epilimnetic water show that phosphorus accumulated from the sediments by benthic coloni es plays an important role in the development of planktonic populations, wh ereas uptake from epilimnetic water by vegetative colonies is insignificant . During the spring and summer of 1996, the cellular phosphorus quota of bo th benthic and epilimnetic Gloeotrichia colonies was monitored in the oligo trophic Peninsula Lake, central Ontario, Canada, in order to detect signs o f luxury uptake and subsequent utilisation during growth. Assays were also used to measure the rate of phosphorus uptake from the sediment and from la ke water. G. echinulata, which overwinters in the form of the benthic akine te packets, is capable of obtaining phosphorus directly from the sediments following germination in early summer, and subsequent growth in the epilimn ion is based almost entirely on accumulated reserves.