STATE DYNAMICS OF ZOOPLANKTON IN THE GULF REGION OF TYUB-KARAGAN

Abstract

Composition, structure, quantitative indicators and seasonal dynamics of zooplankton were normal for this region. Similar seasonal dynamics of zooplankton quantitative indicators was noted in 2014. The average annual values of zooplankton population in 2015 did not change with respect to 2014. The biomass of zooplankton has decreased from 2014 to 2015 due to the less number of large jellyfish.

Keywords: The Caspian Sea, the Gulf of Tyub-Karagan, zooplankton

INTRODUCTION

The structure of the Tyub-Karagan has brought a hope of oil and gas availability according to results of the seismic works and engineering - geological surveys, but the results of the exploration drilling activities on the structure have refuted the projections of availability of hydrocarbon reserves [1-2].

In our opinion, the oil exploration on this structure will not be stopped, because the promising oil structures were opened in the north and south of the Caspian Sea structure, that's why it is necessary to survey the hydrobionts background state in this region.

In this regard, the natural resource users and Atyrau and Mangystau region Akimats continue executing those works.

Earlier we published the results of monitoring activities carried out in 2014 [1-2].

As in previous years, the main three species of zooplankton were found: rotifers, cladocerans and copepods, with copepods (48.87%) predominant in species composition and population, and other species (78%) in biomass.

SUBJECT AND METHODS OF RESEARCH

The Tyub-Karagan Gulf area was chosen as the subject of research. Zooplankton samples were taken from the surface layer of water by the Apstein net and fixed with 4% formalin. Then they were concentrated by settling method. The samples were processed in laboratory conditions according to generally accepted procedures [3 - 5]; the taxonomic composition, population (specimen per 1 m3) and biomass (mg per 1 m3) of zooplankton were determined.

RESULTS OF THE RESEARCH

As in 2014, the water samples for research were taken from 9 observation stations, three from the north, three from the east and three from the north-east sides. The species composition of zooplankton is given in Table 1.

Table 1. Species composition of zooplankton organisms per seasons in 2015.

The table shows that the copepods were predominant during winter period of the research, while the other species were predominant in summer and in autumn.

Tables 2 and 3 show the population and biomass of zooplankton in 2015, and Table 4 shows the comparative average population and biomass in 2014 and 2015.

Figures 1-4 show the diagram of average population and biomass in 2014 and 2015.

The average number of zooplankton in Tyub-Karagan Gulf increased from spring to summer and decreased by autumn and winter in 2015 [6]. The mean values of biomass increased from spring to autumn and decreased in winter. Copepods and rotifers dominated the numbers/population in spring and summer, copepods – in autumn and winter. The copepods mostly dominated the biomass, together with facultative planktons in spring, and together with the cladocerans in summer. The facultative planktons took the dominant position by biomass in autumn. The diversity of zooplankton in terms of the number of taxons and their uniformity was maximum in summer and in spring and decreased by autumn and winter. The composition, structure, quantitative indicators and seasonal dynamics of zooplankton were normal for this region. Similar seasonal dynamics of quantitative indicators of zooplankton was noted in 2014. The average annual values of zooplankton population in 2015 did not change with respect to 2014. The biomass of zooplankton has decreased from 2014 to 2015 due to the less number of large jellyfish.

Table 2. The population of main zooplankton groups per seasons of 2015.

W* - season

Table 3. The biomass of main zooplankton groups per seasons of 2015.

Table 4. Comparative quantitative indicators of zooplankton per seasons for 2014 and 2015

Proceeding from the above:

In connection with the above, the maximum population of zooplankton in the Tyub-Karagan Gulf was recorded in the summer in both 2014 and 2015, and the maximum biomass level was in autumn. The population was mostly dominated by  copepods, in summer – rotifers. In summer the biomass was generally dominated by facultative planktons, and among the latter – large jellyfish. In autumn, the dominant position on biomass was taken by copepods, in some parts of the water area – jellyfish.

The population of zooplankton in Tyub-Karagan Gulf remained at the same level as in 2014, or slightly increased

Reference books

1.        А. Кеnzhjegaliyev, А.А. Abylgazieva, А.К. Shаhmanova. Condition of zooplankton in Tyub-Karagan //American Scientific Journal № 6 (6) / 2016, с.4-6

2.        А. Кеnzhjegaliyev, А.А. Abylgazieva, А.К. Shаhmanova. Condition of hydrobionts in Tyub-Karagan bay// HERALD TarSU of a name of M.Kh. Dulati «Nature and problems of anthroposphere» international science journal - № 3, - 2016. -р.65-72

3.        Procedure of hydrobiology and fish industry research in Kazakhstan”s water reservoirs (plankton, zoobenthos), Almaty 2006, p.27

4.        Procedure of biogeosenose research in internal reservoirs-М.:Publisher «Nauka», 1975.- p. 240

5.        Method procedure of hydro biological analyses of surface water and bed silt L.: Publisher «Hydrometeoizdat», 1983.- p.78-86

6.        Мarine ecological research. Аnnual report. -2015. -р. 1295