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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 2162

Leslie A. Carlough and Judy L. Meyer; Protozoans in two southeastern blackwater rivers and their importance to trophic transfer. Limnol.Oceanogr. 34(1):163-177, 1989

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Protozoan population densities in the sixth-order Ogeechee River and fourth-order Black Creek ranged from 6x10E4 to 11x10E6 flagellates liter-1 and 0 to 1.5x10E5 ciliates liter-1 over a 12-month period. These number approximate those reported for various marine and freshwater habitats. A microcosm study with Ogeechee River water showed a density increase from 4x10E5 to 9x10E6 flagellates liter-1 and 7x10E3 to 4x10E5 ciliates liter-1 in 2 days, representing an estimated net protozoan production of 600 µgC liter-1 day-1. This production was mainly attributed to bacterial growth on DOC and subsequent grazing by the protozoans. Although problems always accompany container studies, this indicates an immense potential for protozoan production in the river. Daily transport of protozoan carbon ranged from 1.08 to 1,360 g, and annual estimated transport down-stream was 60 t of protozoan carbon in the Ogeechee River. Densities of filter-feeding macroinvertebrates are very high in this river. Many of the filter-feeding species are known of feed primarily on amorphous material in the seston, within which protozoans constitute about 4% by carbon content. Since protozoans can be assimilated at relatively high efficiency (~50%), they appear to be a trophic link between the metazoans and otherwise unavailable carbon sources in blackwater rivers.