Foraminifera are successful inhabitants of every aquatic environment from deep oceans to brackish water lagoons, estuaries, and even rarely in freshwater habitats. Sediment samples collected from 3 stations in the Adimalathura Estuary (between latitudes 800’-8024’N and longitudes 77001’–77003’E) exposed to pollution from domestic wastes and coconut husk retting were analysed for a period of one year on monthly basis to study the assemblages of foraminifera. The study has shown that Elphidium advenumis to be the most dominant and most widely distributed foraminifera species of the estuary. Textularia agglutinans, Rotalia becarii and Elphidium crispum are the other abundant species of the fauna. The fauna in general is dominated by the species of Nonionidae followed by Rotalidae. The Shannon-Wiener diversity index (H’) annually ranged from 0 to 1.9225, the Margalef species richness index (d) from 0 to 1.1696, Pielou’s equitability index (e) from 0 to 0.9543 and Simpson’s index of dominance (C) from 0.1822 to 1. The index values in general were least during the southwest monsoon which coincided with a fall in the density of benthic foraminifera. 

Benthic foraminifera, Species diversity, Estuary, Southwest coast of India