Updated bathymetric chart of the East Aral Sea

The Aral Sea is located in an arid region with much sand and salt deposits in the surrounding barren open land. Hence, significant displacements of sediments into the lakebed by the action of wind, water, gravity, or snow are likely. The bathymetry of the lake was last observed in the 1960s, and within the last half century, the structure of the lakebed has changed. Based on satellite observations of the temporal changes of shoreline (Landsat optical remote sensing) and water level (multi-mission satellite altimetry) over more than one decade an updated bathymetric chart for the East Basin of the Aral Sea has been generated. During this time, the geometry of the shallow East Basin experienced strong fluctuations due to the occurrence of periods of drying and strong inflow. By the year 2014 the East Basin fell dry. The dynamic behavior of the basin allowed for estimating the lake's bathymetry from a series of satellite-based information. The river mouth made its impression in the present East Aral Sea, because its shrinking led to the inflow of much sediment into the lake's interior. In addition, salt deposits along the shorelines increased the corresponding elevation, a phenomenon that is more pronounced in the reduced lakebed because of increased salinity. It must be noted that height estimates from satellite altimetry were only possible down to a minimum elevation of 27 m above sea level due to a lack of reliable altimetry data over the largely reduced water surface. In order to construct a complete bathymetric chart of the lakebed of the East Aral Sea heights below 27 m were obtained solely from Landsat optical images following the SRB (Selected Region Boundary) approach as described by Singh et al. (2015).

Calcareous dinoflagellate cysts analysis of sediment cores from the Equatorial South Atlantic Ocean

An overview is presented of the current state of knowledge on paleo-ecological aspects of calcareous dinoflagellate resting cysts. Apart from literature-based information, a discussion of new results is also provided from Equatorial Atlantic surface plankton samples, surface sediment samples and Late Quaternary sediments from two gravity cores. With the aid of redundancy analysis statistics, variations in the calcareous cyst content of both cores are correlated to variations in total organic carbon (TOC). On a global scale, the calcareous cyst distribution in bottom sediments varies with latitude and inshore-offshore gradients. In the Equatorial Atlantic Ocean, enhanced calcareous cyst production can be observed in regions and time intervals with stratified, oligotrophic conditions in the upper water masses.