Extracellular production in relation to growth of four planktonic algae and of phytoplankton populations from Lake Ontario

In four species of planktonic algae both carbon fixation and excretion on an ash-free dry weight basis increase with relative growth rate (K) of the culture measured in log 10 units. In natural populations percentage excretion values are positively correlated with K values; however, environmental factors may be of relatively greater importance and determine the extent of excretion.