The present study evaluated the diversity of epibenthic ciliates in the topsoil habitat of the Ayiramthengu mangrove ecosystem on the southwest coast of India. The study was carried out from June 2014 to May 2015. Ecological parameters like water temperature, pH, dissolved oxygen, conductivity, salinity, nitrate, phosphate and sulphate were also analyzed. The mangrove soil consisted of 84 species of ciliates belonging to 13 subclasses, namely Bicosidae, Cyrtophoria, Haptoria, Heterotrichea, Holotrichia, Nassophorea, Peniculia, Peritricha, Phyllopharyngea, Protocruziidia, Scuticociliatia, Spirotrichea and Suctoria. Among them, Spirotrichea occupied the dominant portion (43%) followed by Phyllopharyngea (24%) and Peniculia (9%). Chlamydodon mnemosyne was the most dominant ciliate (1989 no./cm2 ) followed by Paramecium brusaria (814 no./cm2). The effects of environmental parameters on the community structure of ciliates were evaluated. The maximum number of ciliates (2787 no./cm2 ) and maximum Shannon diversity index (1.692) were recorded in January. The minimum number of ciliates (1803 no./cm2 ) and minimum Shannon diversity were in May (1.477). Similarly, maximum species richness was recorded in May (25.79) and minimum in January (24.38). Canonical correspondence analysis explained the importance of dissolved oxygen, temperature, conductivity, salinity, sulphate, phosphate and nitrate in the distribution and abundance of ciliates. Availability of food, rate of precipitation and the variations in physicochemical characteristics of the mangrove were the factors that determined the distribution of epibenthic ciliates.

Ciliates, epibenthic organisms, Ayiramthengu, spirotrichea