The diversity and distribution of polychaete species under the families Nereididae, Syllidae and Eunicidae in sub-tidal fouling assemblage was studied by submerging wood as test substratum. Wooden panels were fitted onto a raft and submerged in Kudankulam coastal waters (south east coast of India) in pre-monsoon, monsoon and post-monsoon seasons from May 2003 to July 2005. Panels (in replicate) were retrieved from the raft at 15-day intervals. A total of 24 polychaete species belonging to the three families were identified from the test panels. Perinereis cultrifera, Platynereis dumerilii, Syllis variegata, Syllis truncata, and Eunice australis were the dominant species observed on the test panels. The abundance of major polychaete group was varied considerably between the panel series submerged in May 2003 (post-monsoon), November 2003 (monsoon) and July 2004 (pre-monsoon). The major difference in the polychaete community structure was the low abundance of both nereidids on pre-monsoon season panels and the eunicids on monsoon and post-monsoon season panels.

Barnacles are the common fouling organisms encountered in coastal waters around the world. In the present study, breeding biology of the intertidal barnacle Amphibalanus amphitrite (=Balanus amphitrite) was studied for a period of two years (July 2003 to June 2005) in the Kudankulam coastal waters. Results showed that A. amphitrite breeds throughout the year in the study area. A high percentage of individuals with free nauplii in the mantle cavity was observed during March 2004 (47.6%) and May 2004 (41.7%). Barnacles with fertilized eggs in the ovary were high during November 2004 (56%), March 2005 (46.7%) and April 2005 (42.8%). Overall, a peak breeding activity was observed during the March–May period. The breeding activity showed a significant positive correlation with surface water temperature and phytoplankton abundance.

The vertical distribution of fouling communities in Kudankulam coastal waters was studied for a period of one year (January to December 2005) by suspending wooden test panels at 1 m, 4 m and 7 m depths. Panels were submerged on short-term duration (15 days) and long-term basis (cumulative). The fouling organisms observed were barnacles, mussels, ascidians, polychaetes, amphipods and seaweeds. Recruitment was observed on the panels throughout the year with a considerable variation in relation to time and depth. On the short-term series, the fouling biomass varied from 0.218 to 1.23 g.dm−2 (dry wt) at 1 m, 0.23 to 4.72 g.dm−2 (dry wt) at 4 m and 0.241 to 5.66 g.dm−2 (dry wt) at 7 m depths. The biomass of the fouling community that colonized on the long-term panels ranged between 0.79 and 35 g.dm−2 (dry wt) at 1 m, 3.72 and 58.2 g.dm−2 (dry wt) at 4 m and 0.241 and 55.9 g.dm−2 (dry wt) at 7 m depths. At 1 m depth, macro-algae, ascidians (Botryllus tuberatus and Diplosoma sp.) and amphipods were the dominant species. Barnacles, tube worms and ascidians (Didemnum spp.) were abundant on the 4 m and 7 m depth panels. In general, the fouling community recruitment was higher at 4 m than 1 m and 7 m depths.