The Bay of Bengal is a unique region influenced by the Asian monsoon. We present a record of past ocean productivity and carbonate flux based on the fossil remains of calcifying algae over the last 279 000 years from a core in the northern Bay of Bengal. We used AI microscopy to count and measure plankton fossils and identify species. Results show that coccolith export, including of the species Florisphaera profunda, is highest when the monsoon is weak and the water column is more mixed.