Harmful ciliates and dominant population in cultured ponds of algae

With the methods of qualitative and quantitative analysis, the species composition and dominant population of harmful ciliates in algae cultured ponds were studied. Totally 33 species of ciliates, belonging to 3 classes, 9 orders and 27 genus, were found. The dominant ciliate species were Aspidisca steini and Aspidisca tridentata. During the algal cultivation, the number of harmful ciliate species and shown a trend from fewer to more and then to fewer, the most were 25. The change trend of harmful ciliate densities in the ponds was similar to that of algae, and increased with the increase of algal density. The highest densities of ciliates were 21.28 and 21.55 cell·cm~(-2) respectively in two ponds, and then the densities decreased slowly. A. steini and A. tridentata had their densities of 5.3-7.2 cell·cm~(-2) at most.