Detritus as a potential food source for protozoans: utilization of fine particulate plant detritus by a heterotrophic flagellate, Chilomonas paramecium, and a ciliate, Tetrahymena pyriformis

We investigated the direct utilization of fine particulate detritus (dried and homogenized plant material in the size range of bacteria) as a food source for protozoans using axenic cultures of the cryptomonad, heterotrophic flagellate, Chilomonas paramecium, and the hymenostome ciliate, Tetrahymena pyriformis. When fed media containing only particulate detritus, these species revealed growth rates similar to those reported for field populations. The growth rates of Chilomonas fed exclusively particulate detritus were similar to those obtained on a bacterial diet. Considering the high percentage of detritus particles in the size range of bacteria in lakes, our results imply that direct utilization of detritus by protozoans may form an additional pathway of carbon in aquatic food webs that has generally been overlooked.