Journal of the Marine Biological Association of India

Volume 45 Issue 1

Community structure and succession of brackishwater rotifers in relation to ecological parameters

G. Gopakumar and V. Jayaprakas

The rotifer community structure and succession in relation to ecological parameters was investigated at three brackish water habitats of Kerala - a low saline habitat (Veli Lake), a medium saline habitat (Kadinamkulam Lake) and a high saline habitat (Ashtamudi Lake). The ecological parameters of the waters studied in relation to rotifer community were surface water temperature, salinity dissolved oxygen,pH, phosphate, nitrite, nitrate, silicate and chlorophyll a. The main factors determining the community typology of rotifers in these habitats were temperature, salinity and trophic status of waters. The general abundance of rotifers during pre-monsoon season when the temperature was comparatively high, indicated the high temperature preference of rotifers. The key factor for the poor species diversity of rotifers in brackishwater habitats was the wide variation in salinity due to the opening and closure of barmouths. At Kadinamkulam and Ashtamudi lakes, the major species of rotifers recorded were Brachionus plicatilis and B. rotundformis. In contrast, the low saline habitat of Veli Lake harbours the maximum species diversity of rotifers. The eutrophic nature of Veli Lake as revealed by high algal densities and elevated concentration of nutrients resulted in rotifer blooms of different species almost throughout the year. Blooms were recorded mainly for the brachionids namely B. calycflorus B,. mudafus, B . anplaris, B.facatus, B. plicafilis and B. rotundfomis. Dramatic succession of different species was also recorded at Veli Lake.

Date : 30-06-2003