Abstract: To compare the impacts of mariculture modes on ciliate community structure and aquatic environment, an investigation was carried out to analyze the ciliate and the main indexes of water quality in a natural water (control) and the areas with different modes of mariculture, i.e. finfish, shellfish and seaweed (Gracilaria), in the Nan’ao coastal waters of Shantou City in South China. Surface water and sediment samples were collected from each site once every 3-4 days from April to June, 2014. Deposition flux of cysts was studied with sediment traps. A total of 17 species of ciliates were recorded at the four sites and the range of ciliate abundance was 75-150 ind·L^-1. The community structure of planktonic ciliates in seaweed cultivation area was rich and diverse compared to the fish, shellfish and control areas based on the ciliate abundance and species diversity. The highest densities of ciliate cysts were found in the sediment of the fishfarming area, with an average of 1.9×10⁴ cysts·d^-1·m^-2, compared to the other areas. The results indicated that there existed a great difference in the community structure of the ciliates in the waters and the cysts in the sediments among different mariculture sites, and the ciliate community structure was more stable in the seaweed cultivation area compared to the other mariculture areas.

Key words: daily precipitation, temporal-spatial difference, stochastic characteristics, information entropy, flood disaster, China.