Modern and Holocene sublittoral ostracod assemblages (Crustacea) from the Caspian Sea: A unique brackish, deep-water environment

We present a reconnaissance study of sublittoral ostracods from a number of Caspian Sea core-tops collected during a joint French–Russian scientific cruise in 1994 (cores from between 13 and 875 m water depth). The modern ostracods show little depth restriction and this reflects the hydrography of the Caspian Sea which maintains relatively constant conditions (> 5 °C, 13‰ salinity) below 50 m throughout the year. We also present the ostracod faunal record from a 10 m core of laminated sediments, recovered from the Central Caspian Basin (at a water depth of 475 m), which we believe shows repetitive, quasi-cyclic changes in bottom-water conditions over approximately the last 14–15,000 years with a major change at about the late Glacial to Holocene transition. The faunal record from this core illustrates the potential of these sediments for reconstructing environmental changes in the Caspian region during the late Quaternary to Holocene. The continuous occurrence of in situ benthic meiofauna throughout the core also indicates that the bottom-water must have remained ventilated throughout this period although variability in the faunal assemblages may reflect long and short-term changes in the strength of ventilation.