Deep-sea ostracod faunal dynamics in a marginal sea: Biotic response to oxygen variability and mid-Pleistocene global changes

Deep-sea benthic ostracod assemblages covering the last two million years were investigated in IODP Site U1426 (at 903 m water depth) in the southern Sea of Japan. Results show that (1) orbital-scale faunal variability have been influenced by eustatic sea level fluctuations and oxygen variability, and (2) secular-scale faunal transitions are likely associated with the Mid-Brunhes Event (MBE, ~0.43 Ma) and the onset of the Tsushima Warm Current (TWC, ~1.7 Ma). Krithe, Robertsonites, and Acanthocythereis are the three most abundant genera throughout the core, accounting for 78.5 % of total specimens. Multiple Regression Tree analysis indicated that the TWC, the MBE, and oxygen content are the significant controlling factors of ostracod dominance. Changes in assemblages exhibit decline and recovery patterns corresponding to orbital scale cyclicity of sea level changes. In the Sea of Japan marginal ocean setting, this cyclicity shows a close relationship with bottom-water oxygen variability...