Celestine Nwojiji^{1, 2,}, Fabienne Marret¹

Biological Trait Analysis (BTA) has been used to examine the effect of high ocean productivity on the ecological functioning and foraminiferal preservation at the PETM section of ODP site 1215A, Northeast Pacific Ocean. The faunal composition of the studied section indicated a foraminiferal assemblage associated with severe ecological disturbance due to the dominance of opportunistic taxa such as Abyssamina quadrata, Nuttallides truempyi, Tappanina selmensis, P.pleurostomelloides, Quadrimorphina profunda, Bulimina midwayensis and Bulimina tuxpamensis. Over 20 species of benthic foraminifera went into extinction during the PETM at ODP site 1215A. The results from the foraminifera trait analyses suggest that taxa with elongate and bi/triserial tests were the most resilient to the acidification of the ocean as most these taxa increased in abundance during the CIE while taxa with complex apertures and coarse-perforation tend to most vulnerable. Ocean acidification resulting from high productivity also led to the loss of ornamentation in benthic foraminifera as shown by high prevalence of taxa with no ornament. There was no order in the nmMDS ordination of both taxonomic and trait composition of the recovered foraminifera suggesting continual environmental perturbation across the studied section. The scanning electron microscope (SEM) image of some recovered foraminifera revealed evidence of dissolution/etching, extreme recrystallization and secondary calcite cementation on the test. The amount of coccoliths incorporated on the test of some deep infauna species requires further investigation to understand if some foraminiferal taxa construct their test in the dual process of secreting hyaline calcite and incorporation of coccolith plates by agglutinating processes in the later stage of their life history.

foraminifera, PETM, biological trait analysis, palaeoecology, palaeoceanography, Pacific Ocean