For the first time given the ecological and zoogeographical assessment of biological diversity of the Caspian sea, which allow to predict the processes occurring in bottom ecosystems, and to assess the possible consequences, caused by both natural factors and human activities.

Work performed under the GEF / UNEP "Self-assessment of the needs of national potential to manage the global environment" (2009). We present the problems and offer measures for conservation of biodiversity in Dagestan Republic.

The question of establishing the levels of selenium accumulation in fish Marine has consistently attracted the attention of researchers. This is due, no doubt, with a surprisingly high concentrations of trace elements in fishmuscle mass compared with terrestrial animals and the wide spread lack of public consumption of selenium in most countries of the world. By the ability to accumulate selenium species investigated can be arranged in series: carp < rudd < pike Kutum < perch < carp < mullet < silverside < pike < roach < sprat common < gobies < sprat anchovy << sturgeon. It is known that the main source of selenium to fish is the food, although there is some element passes through the gills during respiration. Comparing the results with data accumulation of selenium muscle tissue of fish from different regions of the world indicates the absence of express selenodefitsita in the Caspian Sea.