POPULATION GROWTH AND PRODUCTIVITY OF THE CILIATED PROTOZOA COMMUNITY IN THE ENCLOSURES OF SALINE ALKALINE PONDS
ZHAO Wen DONG Shuang Lin ZHANG Zhao Qi LI De Shang (Ocean University of Qingdao,Qingdao?266003, Shandong, China)
We studied the population growth and productivity by the ciliated protozoa community in the enclosures with and without Silver carp (Hypophthalmichthys molitrix) of saline alkaline ponds productivity, during April September in 1998 The experimental enclosure was a land based enclosure with an area of 0 10 hm 2 in ponds. The enclosure was 20 m 2(4m×5m) in area, 2 0 m in height (1 5 m in water depth), and is made of plastic coated polyethylene woven cloth with a frame composed of wood and bumboo poles. During the experiment, water temperature of experimental enclosures were 22～32℃, conductivity ranged from 1?050～2?400 μs/cm, total alkalinity were 3 02～5 64 mmol/L. Population growth rate and generation times were obtained through in situ experiment. During the culture season, the generation time of major species of protozoa: Askenasia volvox, Ciclidium citrullus, Strobilidium gyrans, Prorodon viridis and Strombidinopsis sp. was 6 93～23 10, 6 30～18 73, 9 90, 9 90～14 75 and 7 62 hr,respectively; population growth rates were 0 030～0 100, 0 037～0 110, 0 070, 0 047～0 070 and 0 091/hr, respectively. The mean daily productivity of total planktonic ciliates in in situ experimental bottles of the enclosures with and without fish were 1 070 25 and 944 25 mg/m 3·d,respectively, during May August, the productivity of the both enclosures at the same times were 1 79 and 9 72 mg/m 3·d,and the ratio of daily P/B calculated by month were 2 50 and 2 03, respectively. The species composition, biomasses, productivity of planktonic ciliated protozoa were influenced by Silver carp and other environmental factors. It is concluded that the biomass and productivity of ciliated protozoa in the enclosures without fish were lower than those of the enclosure with Silver carp. The population growth of ciliated protozoa was subjected to water temperature and trophic status.