Protozoa associated with leaf litter degradation in Coringa mangrove forest, Kakinada Bay, east coast of India

Observations (1995-'96) on mangrove leaf litter revealed a variety of microorganisms dominated by bacteria (5 types), 12 species of flagellates, 2 sarcodines, 17 ciliates, 2 suctorids and 2 sessile ciliates besides several diatoms, nematodes and nauplii. Overall, bacteria outnumbered (4.59 x 105 no. g(-1) dry weight) all others constituting 80-90% of the population followed by flagellates (4.8%), ciliates (4.4%) and, sessile ciliates (0.2%). Chromulina sp., Spumella socialis and Euglena acus (flagellates), Cyclidium sp., Prorodon sp., Euplotoides aediculatus and Zoothamnium sp. (ciliates) were relatively dominant (mean density 4,331 individuals l(-1)) in the litter collected from Avicennia plot. Flagellates, Astasia sp., Heteronema sp. and Paranema sp. and, ciliates, Prorodon sp., Holosticha sp. and E. aediculatus were, however, more common in Excoecaria (mean density 3719 individuals l(-1)). In situ experiments on leaf decay showed that the entire process lasted 12-18 days in summer and 26-32 days during monsoon. Bacteria were the first to settle, followed by nanoflagellates (2-20 mum), microciliates (20-100 mum), macrociliates (100-200 mum) and sessile ciliates. Nematodes indicated culmination. Bacterial (mean) biomass registered highest value (6.43 x 10(-3) mgC g(-1)) within 24 hours but decreased (3.1 x 10(-6) mgC g(-1)) by day-3 to 5. Mean flagellate biomass peaked (32.6 mgC g(-1)) by day-2 and microciliates (92 mgC g(-1)) by day-5 in summer and (47 mgC g(-1)) by day-24 during monsoon. Macrociliates registered highest biomass (168.4 mgC g(-1)) by day-6 in summer but lagged behind until day-26 to day-30 (154 mgC g(-1)) during monsoon. A distinct prey predator relationship, direct dependence of ciliate species on nanoflagellate and bacterial populations as well as, a well marked microbial community succession were evident.