Dynamics of number and distribution of uneven-age individuals of Artemia in deep-water Bolshoe Yarove lake (Altaysky kray)

The cysts of Artemia brine shrimp are considered to be the best starting live food all over the world. There were revealed more than 90 "artemia lakes " on the territory of Altay where preparation of a valuable bioresource is possible. An increasing interest to shrimp cysts has caused development of security actions, including calculation of general stocks and fractions of withdrawal. A certain difficulty in forecasting is a definition of an "inhabited" zone of shrimps and cysts in deep-water reservoirs, including Bolshoe Yarovoe Lake of Altay territory where it is necessary to consider their vertical distribution. Therefore, the aim of the present research was to study distribution non-uniformity of Artemia cysts density on depths for revealing the most productive layer which is necessary for considering at the forecast of valuable bioresource possible collection volumes. The material of studying was hydrobiological data collected at Bolshoe Yarovoe Lake during 2009-2011 from April to October. The selection of hydrobiological samples was spent at permanent stations of supervision located in different parts of the lake. The samples selected from different horizons of a water column (2.0; 4.0; 6.0; 8.0). For the period of research 468 zooplankton samples were collected and processed. For a morphometric research there was used fixed material in quantity: 4750 copies of different-age individuals and 476 copies of adults. For an assessment of depth influence on cysts distribution there was used a one-factorial dispersive analysis. As a distribution aggregation parameter the relation of dispersion to an average value of number shrimps and cysts - parameter D was used. With uniform distribution D < 1 and with group distribution - D > 1. The evolution of 3-4 generations of shrimp was observed in the lake. Nauplii hatching of the first generation was observed in litoral zones, warmer and with the least salinity of water. The life cycle duration of the first generation made 60-69 days. In seasonal dynamics of Artemia common number and biomass the presence of one peak (2009-2010 - in July, 2011 - in June) is marked. In the result of the research non-uniform horizontal and vertical distribution of Artemia shrimp and cysts is revealed. The cysts are more likely to form a congestion possess. The aggregation horizontal parameter (D) of cysts changed from 1.5 up to 2096.4 ant the vertical one- from 4.0 up to 125.4. Distinctions in cysts distribution on depths have a reliable character (F^=5.63, atp=0.01). Their greatest density was marked at the depth of 0-4.0 m in June, 0-2.0 m - in July. During August - October there was observed stratification of cysts on depths, the greatest fraction of their number was at the depth of 0-2.0 m and 6.0-8.0 m, what specifies the process of cysts immersing into deep. Thus, the most productive layer is that of two meters.

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