Climate–ecology linkages influencing morphology and abundance of the <i>Globorotalia menardii</i> during the Late Quaternary, Bay of Bengal

A significant modulation and adaptive response are observed in Globorotalia menardii from the Bay of Bengal (BoB), reflecting its sensitivity to critical and environmentally stressful conditions. The extreme variations in relative abundance indicate a strong influence of temperature and stratification-driven productivity at the regional scale. The size parameters (maximum diameter (D1), intermediate diameter (D2), and keel thickness) of the species reflect its response to climate and ecological changes over the ~3,4000 years BP. Abundance peaks during warm intervals, such as the Bølling–Allerød (B/A), Holocene, and Medieval Warm Period (MWP), and declines during colder phases, including the Last Glacial Maximum (LGM) and Heinrich events, consistent with the species’ thermophilic nature. The size parameters also increase during warm periods, though their variability suggests stronger control by nutrient availability than by temperature alone. Depth-wise morphological patterns reveal robust, symmetrical, and well-developed tests in the younger intervals, contrasting with irregular and underdeveloped forms in the deeper core samples, reflecting ecological stress. Correlation analysis indicates strong positive interrelationships among the test D1, D2 and keel thickness, signifying proportional morphological development, while abundance shows a moderate negative correlation with core depth. These findings demonstrate that both climatic phases and depositional depth regulate the ecological and morphological expressions of G. menardii , underscoring its reliability as a palaeoceanographic proxy for reconstructing past oceanographic variability in the BoB.