Ecology Of Planktonic Ciliates In Shrimp Cultural Water And Studies On Acute Toxicities Of Three Kinds Of Medicine To Ciliates

Composition and variation of planktonic ciliated protozoa were investigated (May to October 2002) in a closed culture-water for Penaeus japonicus near Qingdao. Nine of main environmental as well as biological factors were also sampled, analyzed and presented.Results demonstrate that all the environmental variables including water temperature, salinity, turbidity, pH, chlorophyll a, ammonia-nitrogen, nitrate-nitrogen, nitrite- nitrogen and active phosphorus are higher than those in open water. Among those, conspicuous changes can be detected only in chlorophyll a, ammonia-nitrogen and active phosphorus. Our data exhibit as well that the species number of ciliates reaches its peak in summer, so does the Shannon-Wiener diversity index. However, the abundance and biomass are in a trough in August. Simple correlation analyses indicate that almost all the parameters of ciliates, including species number, abundance, biomass and Shannon-Wiener diversity index are not significantly correlated to the environmental factors, except the correlation between species number and active phosphorus (r =0.51, p<0.05).About 30 ciliates taxa, belonging to 3 classes, 7 orders and 24 genera were identified during the survey. Examination of the structure of ciliates community shows that Prostomatida are the most dominant in abundance, and Oligotrichida take the second place. About 10% of the abundance are Cyrtophorida.Acute toxicities of potassium permanganate, formalin, and Lugol's iodine solution to commonly occurred marine ciliates Diophrys oligothrix, Pleuronema coronation and Euplotes vannus were measured. Linear regression analysis of the results highlighted the close relationships between doses of the medicines and mortalities of the organisms, thus providing a capability to predict toxicity effects from the dose. Toxic effects of the medicines on the ciliates were described in the present paper, and the median lethal concentrations (LCso values) of two hours and twelve hours were given.