## 4 Assessment of the Results  
### Quantitative Assessment of the Environmental Safety Level of the Kazakh Part of the Caspian Sea  
The quality and quantity of water resources flowing into the Caspian Sea from river streams directly affect the water quality in the Caspian Sea. Both shallow water in the Kazakh part and water most close to the mouth of the rivers are especially vulnerable. This is associated with the pollution of water resources from river basins, threaten the existence of the unique and fragile ecosystem of the shallow waters of the Caspian Sea, which may also disappear due to the emerging trend of Caspian Sea level regression. In this regard, it is not possible to assess the impact of the water resources quality on the ecological stability and conditions of the ichthyofauna in without systematic and comprehensive studies of the entire Caspian Sea water area. Nevertheless, today a decrease in the biodiversity of lacustrine life of the Caspian Sea is evident, for example, _Aciperseridae_ by more than an order of magnitude, and _Pusa caspica_ by 4 times comparing with the recorded maximum population (from 1930-2010) [89, 90, 111]. Environmental sustainability (environmental safety--ES) and biodiversity of the ecosystem of the Northern Caspian Sea directly depend on the quantity and quality of the incoming water from the main river basins of Volga and Ural. An equally significant contribution to the pollution of the water body of the Caspian Sea comes from the production and development of hydrocarbons directly on the shelf itself. Under these conditions bioindication methods that perfectly reflect the ecological quality of the organisms' habitat are an effective tool of comprehensive international studiesof the ecological conditions of the Caspian Sea and its feeding streams in combination with water quality analyses. Monitoring methods for determining the quality of the aquatic environment based on bioindication methods are quite common and are occasionally used for various water bodies as an environmental assessment, or to confirm their disastrous conditions. Bioindication first of all, is an assessment tool reflecting anthropogenic or experiencing anthropogenic influences of environmental factors based on changes in the quantitative (or qualitative) characteristics of biological objects and systems [112; 113]. It is well known that living organisms react very dynamically to various toxic compounds. Thus, they can be used as indicators of the environment. Bioindication allows an integral assessment based on the quality conditions of the aquatic ecosystem and the biota inhabiting it in various water bodies and areas. Bioindication at the same time is a very valuable informative complex, in combination with statistical methods. It can be used simple and convenient for the monitoring of different environmental compartments, such as river and lake systems, soils and the atmosphere. Not all organisms can serve as indicators. Therefore, the issues of compiling a list of indicators that are most applicable for the study of specific pollution in a particular environment are being discussed [114]. This was shown in the work on ecological mapping of river and Caspian Sea pollutions based on this method [115]. For decades Polish scientists have successfully used mosses as an indicator of the atmospheric environment when studying pollution by heavy metals at the national, regional and local levels [116]. Studying the quality of the aquatic environment of the Northern Caspian Sea, scientists [117] came to the conclusion, that as objects of bioindication preferable mass-widespread species (not \"rare\" and not \"disappearing\") are suitable, because for them long-term results and regular observations are available. According to these data, the best bioinformatics of the lacustrine ichthyofauna are massive representatives of the suborder Gobioidei from the genus Neogobius: _Neogobius fluviatilis_, _Neogobius gymnotrachelus_, _Neogobius iljini_ and _Neogobius melanostomus_.