Distribution of planktonic Foraminifera in waters of the submarine coral banks in southeast Arabian Sea during winter

Abstract

Twentyfive species of planktonic Foraminifera are recorded from 36 plankton tows collected from waters of the submerged coral banks-Bassas de Pedro, Sesostris and Cora Divh-located at northern end of the Laccadive group of islands in southeastern Arabian Sea. High standing stocks of these organisms are found in plankton tows north of 13-degrees-N where upwelling indicator species namely Globigerina bulloides and Neogloboquadrina dutertrei are observed. Most of the spinose species show higher concentrations in 0-10 m than in 0-200 m tows. Although they form a major component of the fauna, non-spinose species show an increase in relative abundance in December as compared with studies of other winter months in the Arabian Sea and are represented chiefly by those of Globorotalia and Globigerinita. Distribution of species in plankton tows reveals that Globigerinoides ruber, G. sacculifer and Globigerinita glutinata are the most dominant forms, while less dominant species being Globigerinella aequilateralis and Globorotalia tumida. Foraminiferal fauna in general depicts closer affinity with that of equatorial waters of the world and is typical of a tropical reef region under peak winter conditions.