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.

 

Species composition	Number of species
	W	Sp.	Sum.	A
Rotifers	2	3	3	-
Cladocerans	-	-	5	-
Copepods	5	4	6	5
Others	2	5	8	5
Total taxons	10	12	23	10

 

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.

 

Stations	specimen/m3
	Rotifers				Cladoceran				Copepod				Others				Total
	W*	Sp	S	A	W	S p	S	A	W	Sp	S	A	W	Sp	S	A	W	Sp	S	A
1	108	591	8080	0	0	0	466	0	97	761	10807	3443	17	358	5161	908	222	1710	24513	4351
2	10	320	50	0	0	0	80	0	0	910	5383	3615	0	390	1760	3376	10	1620	7273	6991
3	352	205	23201	0	0	0	1576	0	341	74	18879	4239	34	11	8797	938	727	290	52453	5177
4	83	241	9559	0	0	0	621	0	77	121	22034	12694	11	52	3648	1435	171	414	35862	14129

 

5	72	557	18678	0	0	0	598	0	260	285	28885	4867	116	57	6052	382	448	899	54213	5249
6	155	619	22004	0	0	0	1160	0	354	223	17082	43462	22	15	4528	5812	530	858	44773	49274
7	38	173	10534	0	0	0	918	0	108	178	28870	5797	19	25	7962	1000	165	376	48285	6797
8	118	347	10156		0	0	767		276	147	12186		49	12	2977		443	506	26087
9	207	323	27708	0	0	0	4557	0	319	95	15151	49273	112	35	7823	8033	638	453	55240	57306
Averag e	127	375	14441	0	0	0	1194	0	203	310	17697	15924	42	106	5412	2736	373	792	38744	18659

W* - season

 

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

 

Stations	mg/m3
	Rotifers				Cladoceran				Copepod				Others				Total
	W*	Sp	S	A	W	Sp	S	A	W	Sp	S	A	W	Sp	S	A	W	Sp	S	A
1	0,14	0,49	6,47	0,00	0,00	0,00	30,48	0,00	3,12	1,29	13,94	30,10	0,11	0,71	14,51	2,95	3,37	2,48	65,41	33,06
2	0,02	0,34	0,03	0,00	0,00	0,00	3,64	0,00	0,00	1,55	13,50	10,50	0,00	2,92	2,65	9,05	0,02	4,81	19,82	19,55
3	0,43	0,18	19,67	0,00	0,00	0,00	66,96	0,00	11,48	0,18	41,63	14,99	0,47	0,01	27,18	3,21	12,38	0,37	155,44	18,20
4	0,10	0,20	7,68	0,00	0,00	0,00	39,23	0,00	1,75	0,49	43,65	72,50	0,01	0,39	17,99	5,44	1,86	1,08	108,55	77,93
5	0,07	0,53	17,06	0,00	0,00	0,00	47,38	0,00	7,08	0,78	51,49	14,00	1,58	0,45	26,33	2,66	8,73	1,76	142,26	16,66
6	0,18	0,60	18,35	0,00	0,00	0,00	32,24	0,00	10,59	0,35	45,92	168,53	0,12	0,07	9,44	779,09	10,89	1,03	105,96	947,62
7	0,05	0,15	7,82	0,00	0,00	0,00	31,03	0,00	3,51	0,56	63,97	20,18	0,15	0,44	15,67	1800,86	3,72	1,15	118,49	1821,0 4
8	0,14	0,30	9,46		0,00	0,00	32,15		10,38	0,45	15,39		0,13	0,18	12,21		10,65	0,93	69,20
9	0,24	0,24	20,48	0,00	0,00	0,00	119,64	0,00	4,08	0,19	43,46	202,20	2,68	0,36	40,18	1352,57	7,00	0,80	223,76	1554,7 7
Average	0,15	0,34	11,89	0,00	0,00	0,00	44,75	0,00	5,78	0,65	37,00	66,63	0,58	0,61	18,46	494,48	6,51	1,60	112,10	561,10

 

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

 

	Rotifers					Cladoceran				Copepod				Others				Total
	W	Sp	S		A	W	Sp	S	A	W	Sp	S	A	W	Sp	S	A	W	Sp	S	A
population, specimen/m3
2014	191	7571		60	437	0	0	5866	0	292	1029	25094	1547	11	78	13980	1066	493	8679	45000	3051
2015	127	375		1444 1	0	0	0	1194	0	203	310	17697	15924	42	106	5412	2736	373	792	38744	18659
Biomass, mg/m3
2014	0,19	7,25		0,06	0,25	0,00	0,00	194,59	0,00	3,27	0,97	85,05	5,74	0,70	18,85	72,21	998,10	4,17	27,07	351,92	1004,09
2015	0,15	0,34		11,89	0,00	0,00	0,00	44,75	0,00	5,78	0,65	37,00	66,63	0,58	0,61	18,46	494,48	6,51	1,60	112,10	561,10

These figures show that the copepods were predominant (49 and 58 percent accordingly) by population/numbers in 2014 and 2015. If the second place in 2014 goes to other kinds (26%), then the second place in 2015 goes to rotifers (26%), while the cladocerans were less than the others in both 2014 and 2015 (10% and 2% accordingly).



If the copepods were predominant in population, then other species of zooplankton dominated the biomass in both 2014 and 2015 (79 and 75 percent accordingly). The second place on biomass was taken by cladocerans (14%) in 2014, then they moved to the third place in 2015, by giving way to copepods (16%). And rotifers turned out to be the last (0.4 and 2 percent accordingly).

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