Distribution Patterns of Inner Shelf Benthic Foraminifera and Their Relationship to Climatic Conditions in Northeastern Tamil Nadu, India

Abstract

The present study, involving investigations of recent foraminifera from the sediments of the inner shelf off Nagapattinam on the southeast coast of India, was undertaken to document the composition, distribution, and ecology of the foraminifera and their relationship to the climatic conditions of the study area. Thirty sediment samples were collected from depths ranging from 3.4 to 30.8 m during the fieldwork conducted in July 2001 and various ecological parameters were determined. Sediment samples from the sediment-water interface yielded 151 benthic foraminifera species and varieties belonging to 82 genera, 42 families, 21 superfamilies, and 5 suborders, which have been described and illustrated in this study. The spatial and temporal variations of total (“live” + dead) foraminifera populations were analysed. The study shows significant total populations in the collected samples. This was attributed to higher temperatures resulting in higher salinities during this period. Both species and genus diversity increase with increasing depth. In the context of the Indian Ocean tsunami, the pronounced changes in the nearshore continental region will certainly provide a different picture, and the present results would provide a reliable database for comparative post-tsunami studies. The results show a clear relationship between foraminifera and local climatic conditions.