The feeding rates and efficiencies of a marine ciliate, Strombidium sp., grown under chemostat steady-state conditions

Abstract

A marine ciliate of the genus Strombidium isolated from a marine rock-pool, was grown bacteriafree in a chemostat continuous culture system and fed on the alga Pavlova (Monochrysis) lutheri Droop, which was also grown in continuous culture. The growth rate of the ciliate was maintained constant whilst the growth rate of the alga was varied, the latter producing little change in its energy content. The specific filtration and ingestion rates of Strombidium were measured and found, in both cases, to vary inversely as a function of the concentration of available algae. The filtration rate showed a range from 2 to 35 μl · ciliate −1 · day −1 whilst the ingestion rate varied from 0.8 to 3.4 J · ciliate −1 · day −1. The efficiency of ingestion remained constant throughout the experiment with a mean of > 91%, the overall growth efficiency also remained constant but with a mean of only 6.5%. The rates and efficiencies are compared with the results obtained by other workers.