Dr. W. H. Yongue, Jr., B. R. Niederlehner, and P. V. McCormick assisted in the development of the functional group classification and in gathering original data. Dr. M. S. Henebry assisted in experiments conducted in northern Michigan. Sampling in Virginia streams was done by K. E. Trapp. Portions of this work were supported by the Buckeye Cellulose Corporation and by a grant from the University of Michigan Biological Station. N. B. Pratt drew the figures and assisted in the data collection and compilation. Special thanks go to Darla Donald for editorial assistance and to Betty Higginbotham and to Angie Miller for typing this manuscript.
Article first published online: 30 APR 2007
The Journal of Protozoology
Volume 32, Issue 3, pages 415–423, August 1985
How to Cite
PRATT, J. R. and CAIRNS, J. (1985), Functional Groups in the Protozoa: Roles in Differing Ecosystems,. The Journal of Protozoology, 32: 415–423. doi: 10.1111/j.1550-7408.1985.tb04037.x
Presented as part of a symposium, “Protozoan Roles in Ecosystems,” held during the 37th Annual Meeting of the Society of Protozoologists, University of Georgia, Athens, GA, in August 1984.
- Issue published online: 30 APR 2007
- Article first published online: 30 APR 2007
Feeding habits of freshwater protozoa were used to group species into functional, trophic groups. Community structure in differing ecosystems was examined in relation to the number of species occurring in the functional group categories. Six wetland ecosystems and a large river ecosystem were studied. Changes in community structure during the colonization of artificial substrates were also examined. Changes during colonization were studied in a mesotrophic lake, in low-order streams, and in laboratory microecosystems. In the latter case, the response of colonizing communities to a heavy metal toxicant was studied. All communities studied were dominated by bactivorous-detritivorous species and, to a lesser extent, by photosynthetic species. The chief functional role of substrate-associated protozoans appears to be the processing of dead organic matter and its associated bacterial flora. Functional groups utilizing resources other than detrital or mineral nutrients (saprotrophs, algivores, omnivores, and predators) were always minor community components. Colonizing communities were often dominated by photosynthetic species during early colonization stages but were again dominated by bactivorous-detritivorous species at species equilibrium. Low levels of toxicant (Cd) reduced numbers of both photosynthetic and bactivorous-detritivorous species. Higher toxicant levels virtually eliminated photosynthetic species and reduced bacterial detritivores by over one-half. Roles of protozoan species in ecosystems are closely tied to the processing of detritus and the recycling of mineral nutrients. Enumeration of individuals in functional categories is proposed as a simplified method for studying the abundance and activity of protozoa in ecosystems. Examination of changes in functional group composition and the relationship of functional group abundances to rates of carbon processing are suggested for studies of the importance of protozoa to the flow of energy and materials in ecosystems.