Variations and controlling factors of the coccolith weight in the Western Pacific Warm Pool over the last 200 ka

Using a coccolith weight analytic software (Particle Analyser), we analyze most abundant coccolith species in a sediment core from the central Western Pacific Warm Pool (WPWP) and calculate coccolith size and weight variations over the last 200 ka. These variations are compared with the trends of sea surface temperature (SST), primary productivity (PP), sea surface salinity (SSS), and insolation. Our results demonstrate that the size and weight of the coccoliths varied in response to variations of these factors, and their average total weight is primarily related to the relative abundance of the dominant species GEO (Gephyrocapsa oceanica). The variation in weight of EMI (Emiliania huxleyi) and GEE (Gephyrocapsa ericsonii) are mainly influenced by nutrients, and the variation of GEM (G. muellerae conformis) and GEO (G. oceanica) weight are mainly influenced by SST. For all of the taxa weight, PP and SST present apparent precession or semi-precession cycles, we consider that the mono-coccolith weight of the Equatorial Western Pacific is primarily affected by precession drived thermocline and nutricline variation.