V. Kumar¹, R. Vijayan^1,, T. Gangaimani², S. Jeevanandam³

To document the relationship between the substrate characteristics and benthic foraminiferal occurrence in the inner shelf of Gulf of Mannar, off Tiruchendur, sediment samples were collected and studied from 27 stations along three traverses, having depths ranging from 1.5 to 18.5 metres. Surface sediments were collected during May and October in the year 2016 representing summer and pre monsoon respectively and thus the total samples amounted to 54. The traverses are made between south off Veerapandianpatinam and off Alanthalai. During the study 105 foraminiferal species belonging to 40 genera, 29 families, 15 super families and 4 sub orders have been recorded. Among them, 5 have been identified as widespread and abundantly occurring living species since they are found in all the samples collected and studied. The distribution and diversity of foraminiferal fauna are correlated with the substrate characteristics. Their living and total population (living + dead) is relatively higher in the summer (May) than in pre monsoon (October). It has been observed that the living foraminiferal population shows an increase with respect to depth. Siltysand substrate, higher concentration of CaCo3 (< 25%) and moderate organic matter (1.0 – 2.3%) in the substrate are the congenial ecological condition favouring abundance of the living foraminiferal population in the inner shelf off Tiruchendur coast.

substrate characteristics, ecology, recent benthic foraminifera, gulf off Tiruchendur