Influence of Bottom Water Parameters on the Distribution of Benthic Foraminifera from the Gulf of Mannar, Off Tiruchendur, Southeast Coast of India

Foraminifera are found in all marine environments, but they are very particular about the congenial environment for their reproduction, diversity and abundance. To understand the influence of bottom water parameters on the distribution of foraminifera from the shallow shelf region of Bay of Bengal, off Tiruchendur, Southeast Coast of Tamil Nadu, sediment and bottom water samples were collected at 27 stations, along three traverses viz. from off Veerapandianpattinam, off Tiruchendur and from off Alandurai, ranging in depths from 1.6m to 18.5m. The samples were collected during three seasons representing, summer (May 2016), pre monsoon (October 2016) and winter (January 2017) and thus the total samples amounted to 81. A total of 105 species of foraminifera have been identified from 47 genera, 32 families, 16 superfamilies and 4suborders. Among these 105 foraminiferal species, five were found to be widespread and abundant viz. Ammonia beccarii, A. tepida, Asterorotalia inflata, Nonioniodes boueanum and Quinqueloculina seminulam. Various bottom water parameters such as temperature, salinity, dissolved oxygen and pH were determined and correlated with the foraminiferal population. Temporally, higher temperature, salinity, dissolved oxygen and pH of bottom water observed during summer (May 2016) were congenial for higher population in the study area. Optimum conditions for the higher population and abundance of foraminifera are: Temperature: > 32.0°C, Dissolved oxygen: >6.0 mg/l, Salinity: >32 ppt and pH>8.1.