Late Holocene changes in hypoxia off the west coast of India: Micropalaeontological evidences

A study has been carried out to understand benthic foraminiferal and sedimentary organic matter characteristics under low dissolved oxygen conditions off the central west coast of India. Based on the strong correlation between the present-day abundance of rectilinear bi- and triserial benthic foraminifera (RBF) and low dissolved oxygen conditions in the northeastern Arabian Sea, the geologic extent of low oxygen zone off the central west coast of India, is inferred from a core collected from the shallow water region. Persistently high relative abundance of RBF, large proportion of amorphous organic matter and protoperidinioid dinocysts throughout the time-span covered by the core that goes well beyond the beginning of human intervention, indicate that the eutrophication of coastal water and subsequent development of low dissolved oxygen conditions is a natural phenomenon that has been in existence even before anthropogenic influence.