Summary of Abstract Submission

Abstract Submission No. IO50-09-0074PresentationPoster

BENTHIC FORAMINIFERAL ASSEMBLAGES FROM SUNDARBANS: AN ASSESSMENT OF THREATS TO MANGROVES OF INDIAN OCEAN WITH RESPECT TO RISE IN SEA-LEVEL

Areen Sen*1, Punyasloke Bhadury1

1 Indian Institute of Science Education and Research Kolkata, India

ABSTRACT :

Indian Ocean region is almost exclusively bordered by fringing mangroves extending from South Africa to North-Western Australia and faces major threat from increase in Relative Sea Level (RSL). Sundarbans represents the world┐s largest contiguous patch of mangroves located along the Bay of Bengal, Indian Ocean region and only such habitat to support a substantial population of the famous Royal Bengal Tiger. Recent studies report RSL increase in Sundarbans as compared to global trends. Within the Indian part, the Eastern most sectors appear to be more under threat as compared to the Western sectors. Intertidal benthic foraminifera are widely used as indicator of RSL changes. The present study investigates the stability of intertidal benthic foraminiferal assemblages along with other major biomarkers from the previously unexplored Eastern sector of Indian Sundarbans for tracking RSL in this ecosystem. Sediment composition, Total Organic Carbon (TOC) and Carbon isotope signature (δC13) were also studied. Recent investigations have established the utility of δC13 as a major biomarker of changes in RSL. The study recorded an assemblage dominated by agglutinated foraminiferal species represented mainly by Jadammina macrescens, Trochammina inflata and Miliammina fusca congruent with global patterns. Observed TOC values ranged between 0.28 and 1.48 while δC13 ranged between -23.8 and -26.6 indicating terrestrial input of carbon mainly originating from C3 plants. Little deviation was observed between the δC13 values among samples collected over a gap of twenty months establishing its stability as a biomarker of environmental condition and suitability for RSL studies with respect to Sundarbans ecoregion.