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doi:10.2204/iodp.proc.317.209.2015

Introduction

Ostracodes from New Zealand and its surrounding seas have been investigated since the nineteenth century (e.g., Brady, 1866, 1880, 1898). Most of the research is systematic descriptions (Hornibrook, 1952; Swanson, 1969, 1980; Ayress, 1990, 1993, 1995; Ayress and Swanson, 1991; Milhau, 1993; Swanson and Ayress, 1999; Guise, 2001), assemblages and their distribution in the modern seas and bays (Swanson, 1979a, 1979b; Hayward, 1981, 1982; Ayress et al., 1997; Eager, 1999; Morley and Hayward, 2007, 2012), and paleoenvironments during the Miocene (Milhau, 1991) and the late Quaternary (Swanson and van der Lingen, 1997; Hayward et al., 2008). On the other hand, few fossil ostracode data for the Pliocene and early and middle Pleistocene have been reported in and around New Zealand.

Integrated Ocean Drilling Program (IODP) Expedition 317 cored at three shelf sites (U1351, U1353, and U1354) and one slope site (U1352) at water depths between 85 and 344 m (Fig. F1), aiming to understand the relationship between eustatic sea level changes and sequence stratigraphy. At Site U1354, 89% of the Pliocene–Holocene strata were recovered between 0 and 173.9 meters below seafloor (mbsf), and they contain numerous fossil ostracodes. Fossil shallow-marine ostracode assemblages are useful as paleodepth indicators because the habitat of each ostracode species is controlled by environmental factors such as pressure, temperature, and salinity relating to water depth. In this report, we describe temporal changes in dominant fossil ostracodes, the number of specimens per gram, species diversity, and equitability in Pliocene and Pleistocene sediment cores from Holes U1354B and U1354C.

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