The occurrence and diversity of epibionts on pneumatophore and an artificial substratum were evaluated simultaneously for 120 days at the Ayiramthengu mangrove area of the Kerala coast. A total of 46 genera were recorded, including ciliates, flagellates, algae, diatoms, rotifers, nematodes and copepods. Among these forms, 14 genera were specific to the pneumatophore whereas, ten genera were confined to the artificial substratum. The major groups recorded in terms of diversity and abundance were diatoms belonging to 21 genera. Cocconeis, Pleurosigma, Navicula, Nitzschia, Gyrosigma, Biddulphia, Cymbella and Melosira were the common genus recorded from both the substrate. Coscinodiscus, Cyclotella, Campylodiscus, Bacillaria, Diploneis, Licmophora, Striatella and Amphora were recorded only from pneumatophores, whereas Cyclostephanus, Puncticulata, Pinnularia, Lindavia, Encyonopsis were found only on the artificial substratum. The ciliates and rotifers also showed a similar type of substrate specificity. Out of the total 11 Ciliates, Vorticella, Pyxicola, Vaginicola, Zoothamnium, Thuricola and Cothurnia were common and found on both substrata. The ciliates Stentor, Epistylis and Tetrahymina were recorded only from pneumatophores while Frontonia and Ephelota were found on the artificial substratum. In general, the density of epibionts on pneumatophore varied from 65 to 615 no./cm2 while the density of epibionts on artificial substratum ranged from 25 to 805 no./ cm2 . The Shannon diversity index, species richness and evenness varied from 2.018 to 2.077, 0.141 to 0.125 and 0.940 to 0.997, respectively and the values were always higher on pneumatophore than on the artificial substratum. It was duly evident that the most dominant genera were Vorticella followed by Cocconeis, Pleurosigma and Navicula. The study revealed substratum preference of the epibionts.

Epibionts, pneumatophore, artificial substratum, substratum preference, mangrove