Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

Abstract

Temporal variation in abundance and mean proloculus diameter of the benthic foraminiferal species Epistominella exigua has been reconstructed over the last approx. 50,000 yr BP, from a core collected from the distal Bay of Bengal fan, to assess its potential application in palaeoceanographic reconstruction studies. The downcore variation shows significant change in abundance of E. exigua during the last approx. 50,000 yr BP. In view of the present day abundance of this species from areas with strong seasonal organic matter supply, it is concluded that at approx. 7, approx. 22, approx. 33 and approx. 46 kyr BP, strong seasonality prevailed in the distal Bay of Bengal fan, probably indicating either strong or prolonged northeast monsoon or weakened south-west monsoon. For the first time, a strong correlation is observed in abundance and mean proloculus diameter of E. exigua. Based on coherent variation in mean proloculus diameter and abundance, it is postulated that mean proloculus diameter can also be used to infer increased seasonality in organic matter production, thus variation in strength or duration of monsoon. Thus, this study establishes that the down-core variation in the abundance and mean proloculus diameter of E. exigua can be used to infer past climatic variations from the distal Bay of Bengal fan.