• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.378-389
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• 2006

Seasonal changes of biomass and cell size of bacteria and protozoa, and factors affecting their distribution in Lake Paldang and Kyungan Stream were analyzed from April to December, 2005. Bacterial abundance at Paldang Dam and Kyungan Stream was similar, but it did not much increase during hot summer period. Protozoan carbon biomass was much greater at Kyungan Stream compared to Paldang Dam. HNAN generally accounted for the majority of total protozoan biomass, but ciliates made up the highest proportion in April and November at Paldang Dam and June at both sites. PNAN showed low biomass at both sites, but it was high during spring and fall season. Small-sized HNAN ($3{\sim}7\;{\mu}m$) numerically predominated the protozoan community at both sites. Average cell size of HNAN was bigger at Kyungan Stream where nutrients concentration was much higher than Paldang Dam. Average cell size of ciliates varied seasonally; it was relatively small during the summer. HNAN biomass significantly correlated with Chl-a concentration and ciliates biomass at Paldang Dam, indicating that HNAN increase might link to the ciliates increase. At Kyungan Stream, HNAN biomass showed a significant relationship with PNAN biomass, and Chl-a concentration was closely related with both of HNAN and PNAN biomass. Ciliate biomass showed significant relationship with nutrient (TN, TP) and particulate matter (SS) only at Kyungan Stream. At both sites, protozoan biomass was significantly correlated with bacterial biomass, and ciliates were additionally related flagellates. High biomass of microbial components and the close relationships among them suggest that the energy transfer through the microbial loop may important in the plankton food web of Lake Paldang ecosystem.