Implications of finding Peraclis spp. in the Holocene sediments of the northeastern Arabian Sea

Abstract

This first report on the occurrence of Peraclis depressa and Peraclis rissoides from the Arabian Sea, attempts to understand their ecological niche. While pteropods make an excellent proxy for palaeoclimatic reconstruction, Peraclis species have always been overlooked due to their low abundance and have not been explored as potential proxies. In the north-eastern Arabian Sea, the downcore abundances of Peraclis spp. seem to record all the climatic variations especially those of Indian Summer Monsoon, over the early to late Holocene, responding earlier than the foraminiferal assemblage. The signatures of Peraclis species suggest that the 8.2 ka event was a gradual cooling event, rather than an abrupt one. They also serve as an explicit record of the Holocene Climate Optima from the northern Indian Ocean. The downcore signatures of Peraclis are well reflected by the δ13C and δ18O records derived from Globigerinoides ruber in the same core. It has been observed that the Peraclis species are intolerant to high nutrients and prefer cold temperatures. The data suggests P. depressa is more sensitive to temperature variations than P. reticulata and intolerant to high salinity.