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18БИОЛОГИЧЕСКИЕ НАУКИ
ROTIFERA OF THE WETLAND SUDOCHIE (SOUTH ARAL SEA REGION, UZBEKISTAN)
Saparov A.D.
Candidate of biological sciences, dean of faculty, Nukus State Pedagogical Institute, Seitov str., Nukus, 230105 Uzbekistan Kuzmetov A.R. Doctor of sciences, associate professor, Tashkent State Agrarian University, University str., 2, Tashkent 100140 Uzbekistan
Matmuratov M.A.
teacher,
Karakalpak State University, Abdirov str., Nukus, 230112 Uzbekistan Mirabdullayev I.M.
Doctor of sciences, professor, Tashkent State Agrarian University, University str., 2, Tashkent 100140 Uzbekistan
Annotation. The four main lakes of the wetland were studied. There are 38 species of Rotifera, including a new species for the fauna of Uzbekistan - Euchlanis incisa Carlin. During the 4-year environmental monitoring there was a severe drought, which led to a sharp increase in the mineralization of the lakes. The impact of this on the plankton community is considered.
Аннотация. Исследовали коловраток 4 основных озер ветланда. Отмечено 38 видов Rotifera, включая новый для фауны Узбекистана вид - Euchlanis incisa Carlin. В ходе 4-летнего экологического мониторинга наблюдалась сильная засуха, приведшая к резкому повышению минерализации озер. Рассмотрены последствия этого на сообщества планктонных коловраток.
Key words: rotifers, salinity, lakes, Wetland Sudochie, Aral Sea Region, Uzbekistan
Ключевые слова: коловратки, минерализация, озера, Ветланд Судочье, Приаралье, Узбекистан
Introduction
Former gulf of the Aral Sea (in the 19th century), located in northwestern Uzbekistan (fig. 1A), the Wetland Sudochie remains one of the best preserved ecological zones of the Amu Darya Delta, a place of conservation and maintenance of biological diversity in the region. It is one of the largest lake systems in Central Asia that is also important for fishing and hunting ondatra. This is a protected area: The State Ornithological Reserve "Sudochie." At the present stage, the wetland consists of a large number of small and four relatively large lakes, as well as from the surrounding areas (fig. 1B). The total area of the wetland is 46,500 hectares.
In 1999-2002, we conducted hydrobiological researches on the largest wetland lakes, Akushpa, Karateren, Begdulla-Aidyn and Bolshoe Sudochie during monitoring studies of the Global Environmental Facility (GEF) Project "Ecological monitoring of the Sudochie wetland". All lakes are shallow as well as almost all other waterbodies of the lower Amu Darya.
Rotifera is an important component of freshwater ecosystems. Rotifers are one of the most diverse groups in communities of aquatic ecosystems. They are one of the main links in the food chain of waterbodies and belong to the direct consumers of primary production. There is no doubt that there is an active participation of rotifers in many biological processes, especially those related to the productivity of water bodies [2].
In this article, we provide data on plankton rotifers of the 4 main lakes of the wetland Sudochie.
Fig. 1. Maps of Uzbekistan (A) and the Wetland Sudochie (B). * wetland Sudochie
General characteristic of the lakes
Lake Akushpa is situated in west part of the wetland, adjoining to the eastern edge of the Plateau Ustyurt. It is largest lake of the wetland which area in abounding in water years exceeds 12,000 hectares. Depth is 1.0-1.8 m. Approximately 40% of the area is covered by thickets of reed Phragmites australis (fig. 2A-C).
Lake Karateren rounds the Cape Urga of the Plateau Ustyurt (fig. 2D). Depth in central part reaches till 1.82.2 m, average depth is 1.0-1.2 m, area is ca. 475 hectares. The lake is surrounded by thickets of P. australis and cattail Typha angustifolia.
Lake Begdulla-Aidyn is situated in central part of the wetland. Depth is not more 1.4-1.5 m, average depth is 0.6-0.8 m, area is ca.1850 hectares.
Lake Bolshoe Sudochie is situated in south-eastern part of the wetland and has elongated shape. Maximal depths are not more than 1.2-1.4 m; the area is 5100 hectares. The basic reach of Bolshoe Sudochie Lake practically has no thickets of surface vegetation; however, the coast of the northern bay of this lake are covered with thickets of reed forming numerous islets of vegetation in this area, cattail associations dominate the other part of the coastal line.
Mineralization of water in the lake system varied by year and season (table 1). The main reason for the high mineralization of water in the lakes is the inflow of drainage water, with which it annually receives from 2,000 to 2,600 thousand tons of salt. Absence of water runoff from the lake system and the high intensity of evaporation (about 1200 mm per year) contribute to an annual increase in water mineralization by an average of 1 g/l. In 2001, the flow of water into the wetland by collectors almost completely stopped, which led to sharp increase in the mineralization of water in lakes, and the lake Bolshoe Sudochie in the summer completely dried up. The inflow of water in 2002 led to the filling of lakes with water and a significant decrease in mineralization. All this has had a dramatic impact on the biota of the lakes.
1999 2000
Fig. 2. Wetland Sudochie. A-C, Lake Akushpa in 1999-2001; D, Lake Karateren
Table 1
DYNAMIC OF MINERALIZATION OF THE LAKES (G/L) IN 2000-2002_
Lakes 2000 2001 2002
April June Octob. April June Octob. April June Octob.
Akushpa 15-25 25-35 25-45 25-40 40-50 50 40-50 10-20 10-20
Karateren 7 8 12 8 15 50 25-35 5 8
Begdulla-Aidyn 3 6 8 8 40 50 10 5 5
Bolshoe Sudochie 3 6 12 8 dried dried 10-20 5-10 5
Material and methods
The objects of research are plankton rotifers, which were studied by standard methods [4-6]. The quantitative samples were collected by a 10-liter bucket and filtered 100 liters of water through a conical net of capron sieve no. 76. Quality samples were collected by stretching the plankton net. Samples were selected in pelagiali, in the thickets of macrophytes and on coastal shallow waters and fixed by formalin (fig. 3).
Fig. 3. Collecting samples
The quantitative treatment was carried out under the stereomicroscope MBS-7, using Bogorov camera and a stamp-pipette. Individual body weights were calculated using allometric growth formulas that link body length and weight [6, 7].
Results
A total of 76 taxa plankton animals were observed during the monitoring period - 1 species of ciliates, 1 species of turbellaria, 1 species of annelide, 38 species of rotifers (table 2), and 36 species of crustaceans. This is noticeably more than was known for Lake Sudochie in previous periods of study. For example, in 1933 there were 50 species of plankton animals, and in 1970-1986 - 48 species. The greater diversity of zooplankton is mainly due to more detailed research during the project.
Seven species of Rotifera are new to the fauna of the South Aral Sea Region: Testudinella elliptica (Ehrenberg), Euchlanis incisa Carlin, Cephalodella sp., Lecane plesia (Myers), L. stenroosi (Meissner), L. thalera (Harring et Myers), Lophocharis kutikovae Mirabdullaev. A new species for the fauna of Uzbekistan is E. incisa.
SPECIES COMPOSITION OF ROTIFERA IN LAKES OF THE WETLAND
Lakes Begdulla- Aidyn Bolshoe Sudochie Karateren Akushpa
Species \ Years 0 о о <N о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2
Asplanchna sieboldi (Leidig) - - - + - - - - - - - -
Bdelloidea gen. sp. + - + - - + - + + - - -
Brachionus angularis Gosse + - + + - + + - - - - -
B. calyciflorus Pallas +
B. plicatilis Müller + + + + + + + + + + + +
B. quadridentatus Hermann + + + - - + + + + - + +
B. rotundiformis Tschugunoff + - + + - + - - + + - -
B. rubens Ehrenberg +
B. urceus (Linnaeus) + - + - - + + - - - - -
Cephalodella sp. - - - - - - + - - - - -
Colurella obtusa (Gosse) + - - - - - + - - - - -
Euchlanis dilatata (Ehrenberg) + - + - - + + - + - - -
E. incisa Carlin - - - - - - - - + - - -
Filinia longiseta (Ehrenberg) + - - + - + - - - - - -
Hexarthra oxyuris (Zernov) + - + + - + + - + + + +
Keratella quadrata (Müller) + + + + + + + + + + - -
K. tropica (Apstein 1907) + - - + - - + - - - - -
K. valga (Ehrenberg) + - + + - - + + + - - -
Lecane bulla (Gosse) - - + + - - + - - - - -
L. closterocerca (Schmarda) - - - - - - - - + - - -
L. lamellate (Daday) - - + - - + - - - - - -
L. luna (Müller) - - + - - + + - + - - -
L. cf. punctate Murray + - + - - + + - - - - -
L. plesia Myers - - - + - - - - - - - -
L. stenroosi Meissner + - - - - - + - - - - -
L. thalera (Harring et Myers)
Lepadella patella (Müller) - - - - - - + - - - - -
Lophocharis kutikovae Mirabdullaev - - - - - - + - - - - -
Notholca acuminata (Ehrenb.) + + + - - + + - + + - -
N. squamula (Müller) - - - - - - - - + - - -
Polyarthra vulgaris Carlin - - + + - +
Proalides sp. - - + +
Synchaeta sp. + - + + - + + - - + - -
Testudinella elliptica (Ehrb.) + + +
T. patina (Hermann) - - + - - + + + + - - -
Trichocerca sp. + - - + - + - - - - - -
Trichotria pocillum (Müller) + - + - - + + - - - - -
Tripleuchlanis plicata (Levan.) +
Total species 21 4 20 15 2 19 21 6 14 7 4 4
Species \ Years 0 о о 2 о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2 0 о о 2 о о 2 2 о о 2
Lakes Begdulla- Aidyn Bolshoe Sudochie Karateren Akushpa
The sharp increase in mineralization caused by the 2001 drought (table 1) led to a sharp decline in the diversity of rotifers (table 2). It recovered (with the exception of Lake Akushpa) in 2002, when inflow of water into the lakes was much more.
In taxonomic respect, the most diverse were rotifers. During the salinization of the lakes, the proportion of rotifers and cladocera in the diversity of zooplankton was constantly decreasing, and the proportion of copepods increased (table 3). In 2002, due to the desalination of lakes, the original taxonomic structure of the wetland zooplankton was largely restored.
TAXONOMIC STRUCTURE OF ZOOPLANKTON OF THE WETLAND SUDOCHIE (PART OF _NUMBER OF SPECIES IN GENERAL DIVERSITY OF ZOOPLANKTON, %)_
Taxa 2000 2001 2002
April June October April June October April June October
Rotifera 33 60 19 38 23 25 36 48 53
Cladocera 22 10 12 0 0 0 0 10 15
Copepoda 18 30 56 48 69 75 45 38 30
The index of the saprobity of the lakes Karateren, Begdulla-Aidyn and Large Sudochie fluctuated in the range of 1.5-1.8, which corresponds to the р-mesosaprobic zone (moderate organic pollution). For Lake Akushpa, a reliable assessment of the range could not be obtained due to the lack of data on the indicator value of most halophilic organisms.
References
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