Abstract The South Asian monsoon system significantly impacts the Bay of Bengal (BoB) and is crucial for studying the region’s paleoceanography and paleoclimate. The present study investigates radiolarian assemblages from a sediment core (SK 329/1) spanning the last 44 kyr BP retrieved from the northern tip of the Ninetyeast Ridge, the southern BoB. The radiolarian abundance and diversity were analysed as proxies to reconstruct past oceanographic and monsoonal conditions, as well as paleoproductivity, revealing significant climatic events such as the Younger Dryas (YD), the Heinrich events (H4–H1), the Last Glacial Maximum (LGM), and the Bølling–Allerød (B/A) interstadial. The present study reveals distinct temporal shifts in radiolarian assemblages, with spumellarians dominating warm, nutrient-poor interglacials and nassellarians thriving in cold, nutrient-rich glacial phases. The abundance of species such as Acrosphaera spinosa and Acanthosphaera actinota during the LGM and the Heinrich events reflects enhanced paleoproductivity driven by intensified upwelling and cooler sea surface temperatures (SSTs). Conversely, the warm-water species like Dictyocoryne truncatum and Spongaster tetras tetras flourished during the Holocene, indicating warm, low-salinity conditions. This study highlights the sensitivity of radiolarian communities in the Bay of Bengal to monsoon-driven variations, oceanic productivity and climate-induced environmental changes of the region. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> Shifts in radiolarian assemblages over the past 44 kyr BP in the southern Bay of Bengal reflect paleoceanographic changes associated with glacial and interglacial phases. </ItemContent> <ItemContent> Acrosphaera spinosa and Acanthosphaera actinota suggest increased paleoproductivity during the Last Glacial Maximum (LGM) and the Heinrich events, driven by upwelling and cooler sea surface temperatures. </ItemContent> <ItemContent> The dominance of warm-water species (Dictyocoryne truncatum and Spongaster tetras tetras) during the Holocene indicates warm, low-salinity conditions influenced by intensified monsoonal activity. </ItemContent> <ItemContent> The temporal distribution of radiolarians corresponds with major global climate events, including the Heinrich events (H1–H4), the Bølling–Allerød (B/A) interstadial, and the Last Glacial Maximum (LGM). </ItemContent> <ItemContent> This study highlights the sensitivity of radiolarian communities in the Bay of Bengal to monsoon-driven variations, providing key insights into the relationship between regional monsoon systems and global climate dynamics. </ItemContent> </UnorderedList>

Paleoceanographic and climatic shifts in the southern Bay of Bengal over 44,000 years: Insights from radiolarians

期刊论文
发表日期：

2025年9月27日

查看全文

Kavya Aravind,
N R Nisha,
A K V Haifa,
Rajveer Sharma,
F Lujain

摘要

Abstract

The South Asian monsoon system significantly impacts the Bay of Bengal (BoB) and is crucial for studying the region’s paleoceanography and paleoclimate. The present study investigates radiolarian assemblages from a sediment core (SK 329/1) spanning the last 44 kyr BP retrieved from the northern tip of the Ninetyeast Ridge, the southern BoB. The radiolarian abundance and diversity were analysed as proxies to reconstruct past oceanographic and monsoonal conditions, as well as paleoproductivity, revealing significant climatic events such as the Younger Dryas (YD), the Heinrich events (H4–H1), the Last Glacial Maximum (LGM), and the Bølling–Allerød (B/A) interstadial. The present study reveals distinct temporal shifts in radiolarian assemblages, with spumellarians dominating warm, nutrient-poor interglacials and nassellarians thriving in cold, nutrient-rich glacial phases. The abundance of species such as Acrosphaera spinosa and Acanthosphaera actinota during the LGM and the Heinrich events reflects enhanced paleoproductivity driven by intensified upwelling and cooler sea surface temperatures (SSTs). Conversely, the warm-water species like Dictyocoryne truncatum and Spongaster tetras tetras flourished during the Holocene, indicating warm, low-salinity conditions. This study highlights the sensitivity of radiolarian communities in the Bay of Bengal to monsoon-driven variations, oceanic productivity and climate-induced environmental changes of the region.

Research highlights

Shifts in radiolarian assemblages over the past 44 kyr BP in the southern Bay of Bengal reflect paleoceanographic changes associated with glacial and interglacial phases.

Acrosphaera spinosa and Acanthosphaera actinota suggest increased paleoproductivity during the Last Glacial Maximum (LGM) and the Heinrich events, driven by upwelling and cooler sea surface temperatures.

The dominance of warm-water species (Dictyocoryne truncatum and Spongaster tetras tetras) during the Holocene indicates warm, low-salinity conditions influenced by intensified monsoonal activity.

The temporal distribution of radiolarians corresponds with major global climate events, including the Heinrich events (H1–H4), the Bølling–Allerød (B/A) interstadial, and the Last Glacial Maximum (LGM).

This study highlights the sensitivity of radiolarian communities in the Bay of Bengal to monsoon-driven variations, providing key insights into the relationship between regional monsoon systems and global climate dynamics.