Changes in the composition of a tropical marine fouling community at a power plant discharge

Abstract

The settlement rates of macrofouling organisms and the structure of marine fouling communities at the seawater intake and cooling water discharge of Madras Atomic Power Station, India were studied for a period of 2 years. The fouling community at the intake was composed of diverse groups of marine organisms. Of the 139 species observed at the intake, barnacles, mussels, hydroids, bryozoans, ascidians, echinoderms and sponges were major components. The fouling community at the discharge was much less diverse. Approximately 25% fewer species were observed and the fouling community was dominated by macroalgae including Enteromorpha intestinalis. Bryozoans, hydroids, sponges and echinoderms were absent at the discharge site. Hydrobiological features were compared. The discharge site was characterised by elevated temperatures, increased suspended matter and decreased chl a and dissolved oxygen. Analysis of zooplankton samples showed increases in bivalve, barnacle, and polychaete larvae at the discharge site compared to the intake due to release from the fouling community within the power plant cooling system. Differences in the fouling communities can be attributed to physico‐chemical disturbances in the cooling waters and to conditions that favour the colonization and growth of macroalgae at the discharge site.