Aquatic biotopes are, due to their features, among the most disposed ecosystems to bioinvasion. Serbia waters are not an exception, with and increasing colonization by allochthnous organisms observed there during the last few decades. Non-indigenous aquatic species were found among plants, vertebrates and invertebrates. The aim of this work is to present the current status of aquatic ecosystems in Serbia in regard to biological invansions and to point up to the problem of introduction, presence and influence of aquatic non-indigenous species.

The Water Book maintenance is obligated. The electronic form of Water Book and following documents provides an insight into data from issued water acts, in a simple, systematic and arranged way, which enables easy and fast search, according to assigned key, of data extraction and report printing. Program package is provided by Republic Directorate for Water. The implementation of Water Book program is realised in the Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia - Republic Directorate for Water. Public water enterprises and communities that have technical capacities for program installation.

The paper deals with the essential of economic insurance within the whole economy procedure in the water management companies. As it is well known, the fundament of insurance is risk itself. The risk, by its appearance, power and intensity, has its impacts on processes, objects and activities in the water management. That is why is very important to know and apply knowledge, awareness and comprehension about risk management in the field of water management. Any sort of risks must be analyzed, planned, controlled, organized, prevented, repressed, averted and fixed in order to decrease detriments and disadvantages. The best way to preclude all predicted and unpredicted tribulations and costs is to go all-out for the rules of covenanted and unsolicited types of insurance. The paper also gives a brand - new approach to bypassing risks within management by the system of covenanted and unsolicited insurances.

Contents of labile (acid-soluble) sulfides were determined in the upper layer of bottom sediments at 80 stations on the Caucasian shelf of the Black Sea. Maximum values of this parameter occurred in black mud accumulated in zones of intense pollution in the Gelendzhik and Tsemess bays and in shelf areas adjacent to large health resort objects and to seaports. Contents of acid-soluble sulfides in sediments varied from 400 to 900 mg S/dm**3 of wet mud. In zones of moderate pollution they varied from 200 to 400 mg S/dm**3. Rate of sulfate reduction was 10-40 mg S/dm**3 of wet sediment per day. Obtained data show that accumulation of labile sulfides in the upper layer of shelf bottom sediments is directly related to anthropogenic pollution and is one of the most hazardous environmental aftereffects.