Caspian Sea
The Caspian Sea, like the Black Sea, Namak Lake, and Lake Urmia, is a remnant of the ancient Paratethys Sea. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions, and is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.
Caspian seal
Several recent cases of large numbers of Caspian seals dying due to canine distemper virus have been reported, in 1997, 2000, and 2001. In April 2000, a mass die-off of Caspian seals was first reported near the mouth of the Ural River in Kazakhstan. It spread south to the Mangistau region, and by the end of May, more than 10,000 seals had died along the Kazakhstan coast. High death rates were also recorded in May and June along the Apsheron peninsula of Azerbaijan and the Turkmenistan coast.