ANNALS OF AGRARIAN SCIENCE, vol. 11, no. 1, 2013 ИЗВЕСТИЯ АГРАРНОЙ НАУКИ, Том 11, Ном. 1, 2013
ЭКОЛОГИЧЕСКОЕ СЕЛЬСКОЕ ХОЗЯЙСТВО И ОХРАНА ПРИРОДЫ ECOLOGICAL AGRICULTURE AND NATURE CONSERVATION
QUALITATIVE STRUCTURAL FEATURES OF PHYTOPLANKTON COMMUNITY IN THE LAKE SEVAN AND ITS CATCHMENT BASIN
A.A. Hovsepyan, T.G. Khachikyan, L.R. Hambaryan, A.E. Martirosyan InstitutInstitutee of Hydroecology and Ichthyology of the ScientificScientific Center for Zoology and Hydroecology of the National Academy of Sciences of Armenia 7, P. Sevak str., Yerevan, 0014, Republic of Armenia; [email protected] ; [email protected]; lus [email protected]; [email protected] Received: 12.09.12; accepted: 23.11.12 Increasing pollution levels in Lake Sevan catchment basin is the main cause of anthropogenic eutrophication. It is generally known that the environmental state of the reservoir catchment area directly affects the processes occurring there. In order to characterize the current ecological status of Lake Sevan and its catchment basin, phytoplankton community composition has been investigated. Furthermore, the specific aim was to identify similarities in the qualitative composition of the algal community in Lake Sevan and its main tributaries according to Jaccard similarity index, and to show the possible influence of qualitative parameters of rivers on catchment basin to form floristic composition of phytoplankton community in Lake Sevan.
INTRODUCTION Lake Sevan is the largest freshwater reservoir in Transcaucasia and one of the largest high altitude lakes in the world. This lake is included in the list of Wetlands of International Importance according to the Convention on Wetlands of International Importance [1]. Lake Sevan plays an important role in the regulation of surface water and groundwater, to mitigate the effects of regional climate change and offers a promising source of drinking water. Large scale development of water resources such as energy conversion and irrational utilization started since 1930s of the last century, led to a decrease in lake level (20.2m) resulting in a profound change: lake eutrophication has occurred and had not any analogues [2 5]. As a consequence of the reduction in water mass of Lake Sevan, environmentally unsound economic intensive and extensive activities in the catchment area the latter increased the influence on the lake. One of the obvious signs of eutrophication in Lake Sevan was the seasonal succession of phytoplankton species: in pelagic plankton new species appeared, previously found only
1 in coastal areas and bays, while some species have been found in the lake for the first time [2, 6 11]. During different stages of lake investigation, changes in the role of phytoplankton species were observed periodically having displaced species of planktonic algae, which were characteristic of the lake natural period prior to level lowering. The purpose of the current work is to assess the species diversity of phytoplankton of Lake Sevan and its main tributaries as well as to identify similarities in the species composition of the planktonic algae in Minor Sevan and Gavaraget, Dzknaget rivers, and phytoplankton communities in Major Sevan and Masrik, Makenis, Arpa, Vardenis, Argichi, Lichk rivers.
OBJECTIVES AND METHODS The algological material was collected at two following stations: №4 Minor Sevan, №22 Major Sevan and 8 major tributaries. Water samples were collected, using a Ruttner bathometer with four main horizons of pelagial part (lake surface, 10 m, 20 m and bottom layer). Phytoplankton sampling at Lake Sevan was carried out during April, July, October and November, while phytoplankton samples from the tributaries were assessed from March to November. In general, 30 phytoplankton samples were analyzed taken from Lake Sevan and 70 samples taken from Masrik, Makenis, Arpa, Vardenis, Argichi and Gavaraget rivers, which flow into Major Sevan, and rivers Gavaraget and Dzgnaget flowing into Minor Sevan.
EXPERIMENTAL SECTION Collection, preservation and processing of algae were implemented according to standard methods [12,13]. Identification of algal species specificity was done by using various determinants [14 18]. Jaccard’s index was used to determine algal communities’ similarity and it is given as follow: k = c/a + b • 100% where c the number of species common to both sites, aaa and bbb b the number of species found at each site [19, 20]. The saprobic value of indicator phytoplankton species was defined [21].
RESULTS AND ANALYSIS As it is already known, algal species composition might serve as integral indicator of cumulative effects of factors that characterize the ecological status of water bodies, trophic level and the degree of water pollution [22, 23]. According to 2011 data, a total of 157 taxa of planktonic algae below the rank of genus have been recorded in Lake Sevan and its main tributaries: 58% diatoms (Bacillariophyta), 21% green algae (Chlorophyta) and blue green algae (Cyanophyta) 16%.
2 The number of species of planktonic algae in the lake was 70: 38 (54%) diatoms, 21 (33%) green algae and 7 (11%) blue green algae. Solitary species were following: Dynophytes Peridinium sp., Phacus pleuronectes (O.F. Müller), Trachelemonas hispida (Perty), Stein Emend Defl. and T.volvocina (Ehrenberg) from Euglenophyta, which complemented the overall phytoplankton diversity (Table 1). More species were identified in Minor Sevan compared with the other part of the lake (60 in Minor Sevan, 47 in Major Sevan) that may be due to the relatively higher frequency sampling observations. In recent years, diatoms’ biodiversity had a tendency of increase within algal community of Lake Sevan [24]. On the other hand, in the 1930s green algae were qualitatively dominant, according to previous investigations [6, 9 11, 25 28]. Thus, Navicula (5), Cyclotella (4), Achnanthes (3), Fragilaria (3), Melosira (3), Nitzschia (3) were the most diverse genera among diatoms, while Ankistrodesmus (5) and Oocystis (3) in the green algae. Blue green algae Aphanizomenon flos aquae Ralfs. in plankton was not observed, which caused water bloom in the lake in July 2006. Representatives of the genus Anabaena were identified as solitary: A. flos aquae (Lingb.) Breb. and A. cylindrica Lemm., the growth of the first increased rapidly in certain parts of the lake during summer 2010, particularly near the Sea gull island the density of Anabaena in blooms spots was reaching several tens of millions of cells (in a liter of water ~ 2 million cells) [29]. The period of increasing Lake Sevan level is inherent in the emergence of phytoplankton species which were not reported by previous investigators and indicates the change in conditions of the lake. Thus, during the last few years a new member of the genus Cyclotella was found C.stelligera Cleve et Grunow, which in some seasons together with other species of Cyclotella (C. kuetzingiana Thw., C. comta (Ehr) kutz. Var. Comta and C. meneghiniana Kutzing) significantly contribute to the total phytoplankton biomass. Another representative of diatoms Ceratoneis arcus Ehr., is a frequently occurring species in the tributaries of Lake Sevan [30,31]. For the first time Ceratoneis has been discovered in 2005 in the pelagic zone of Lake Sevan and later dropped out the plankton and detected again. The genus Fragilaria included increases in abundance of two new species F. capucina Desm. and F. construens Desm. generally found in the coastal and catchment area of the lake. Earlier, F. crotonensis Kitton was playing an important role in phytoplankton during spring 1975 1981 [2, 7, 10] as well as during several years of the lake level secondary lowering period when it was included in the list of dominant species [11]. Also blue green algae Aphanothece stagnina (Spleng.) B. Peters et Geitl. appeared in 2009 and in March of the next year ousted from the community the other representative of this genus A. clathrata W. et. G.S. West f. clathrata, which was formerly the permanent representative of the blue greens in the lake. It should be noted the appearance of green algae Scenedesmus obtusus Meyen. Occasionally occurring in 2005, in November 2006 it became the dominant species of phytoplankton community. In Major Sevan S.obtusus was the dominant species in terms of algal biomass, accounting for 33.4% of the total biomass, although in another part of the lake it was the second subdominant species in terms of biomass (23.7%) after Coelastrum microporum Nag. (26.4%).
3 131 specific and intraspecific taxa belonging to 5 phylums of planktonic algae were identified in 2011 in the tributaries of Lake Sevan. Thus, diatoms were the most species rich group (83 species; 63%). Blue greens were the second most numerous forms (24 taxa; 18%), while the green algae were represented by 21 taxa. Two species of euglenoids and 1 species of yellow green algae were recorded (Table 1). The highest rate of species richness was observed in Masrik (71) and Lichk Rivers (63) as during the previous year, while the lowest diversity was distinguished in River Vardenis (30 species). The highest rate of diversity was inherent in genera Navicula (11), Nitzschia (11), Cymbella (8), Pinnularia (6), Gomphonema (5), Surirella (4), Fragilaria (4) and Achnanthes (4) from the diatoms, Oscillatoria (7), Phormidium (4) and Anabaena (3) from the blue green algae. The genera Scenedesmus (7) and Oocystis (3) among green algae represent the most diverse representatives. According to Khudoyan [32], prevalence of diatoms was typical for the phytoplankton of the main tributaries of Lake Sevan in the early 1990s that generally characterized reoplankton. Qualitatively the diatoms were the dominant phylum in those years (63): the second dominating taxa were green algae (42), while blue green algae were represented by nine species. The increase in diatoms diversity (83) and blue green algae (24) was observed, while green algae were relatively low (21) in 2011 compared to the previous period. Thus, increase in the diversity of blue green algae was primarily due to increased amounts of toxic species (e.g. genus Oscillatoria 7 species). In both parts of Lake Sevan and its main tributaries on the basis of geographical distribution of the phytoplankton community were dominated cosmopolitan species: in the second place were boreal species. Solitary species were also found inherent arcto alpine latitudes. Characteristics of geographical distribution of significant numbers of species have not been studied (44% of the total number of the phytoplankton community species) (Table 2). In the composition of planktonic algae of Lake Sevan and its major tributaries according to accepted saprobity scale, a large proportion fell to β mesosaprobic species. Particularly were distinguished the following observation points: Minor Sevan 32%, Major Sevan 25.5%, r. Gavaraget 45.0%, r. Vardenis 43.3%, r. Makenis 42.0%. The share (16.6% (r. Vardenis) to (44.6% Major Sevan)) of species not included in the list of saprobic organisms was also significant (Table 2). The proportion of α mesosaprobic species in the algal list was ranged from 3.7% (r. Argichi) to 11.8% (r. Arpa). In the phytoplankton community were species which saprobic value was not found out. Application of Jaccard’s coefficient revealed insignificant similarity between phytoplankton communities of lake and its tributaries that might serve as a sign of a weak influence of the rivers species composition on Lake Sevan to form its qualitative structure. According to Khudoyan [32], in the early 90's of the last century Jaccard’s coefficient also were not observed significant degree of similarity between phytoplankton community and algocenosis of Lake Sevan and its main tributaries.
4 CONCLUSION There is a trend of qualitative prevalence of diatoms expanding in Lake Sevan observed in the years of its level rise. This is probably contributing to changes in lake conditions as a result of raising its level. Replenishment of particular phytoplankton species is being observed which (I mean species) have not been previously recorded: some of those species during particular seasons had a dominant position in the community. Frequent reconstruction of dominant complex, changes in significance of different phylums and taxa of planktonic algae, periodical loss of some species inherent to Lake Sevan and their further integration in the community in different stages of research suggests the instability of the ecosystem. Phytoplankton of Lake Sevan main tributaries retains similarities in qualitative composition of algal species: the most taxonomically diverse group were diatoms. However, blue green algae were subdominant species in 2011, while green algae were on the second place during the early 1990s. The main tributaries flow into Lake Sevan species richness was found in Rivers Makenis and Lichk, while in River Vardenis the lowest amount of phytoplankton species was recorded. During 2011 species composition of planktonic algae revealed a significant proportion of species indicators variations in degrees of contamination including β mesosaprobic species. Phytoplankton communities of Lake Sevan and its main tributaries were characterized by the prevalence of cosmopolitan species. The second place took species that were inherent to boreal zones and the geographical distribution patterns have not been studied. Application of Jaccard’s coefficient revealed insignificant similarity of phytoplankton communities in the lake and its tributaries, which suggests that the dominant phytoplankton species of main tributaries of catchment basin at this stage have little influence on the formation of the qualitative composition of phytoplankton in Lake Sevan.
REFERENCES 1. On line: http://www.ramsar.org/pdf/lib/ramsar manual4rus.pdf 2. Legovich H. 1979. Blooms of the lake Sevan. In: Ecology of Hydrobionts of Lake Sevan // Publ. House AS ASSR, Yerevan, pp.51–74 (in Russian). 3. Oganesyan R. and Parparov A. Ecological Aspects of Lake Sevan Problems. In: Production Processes in Lake Sevan // Publ. House AS ASSR, Yerevan,1983, pp. 145 170 (in Russian). 4. Oganesyan R. Lake Sevan Yesterday, Today… // Yerevan, 1994, 478 pp. (in Armenian). 5. Parparov A. Some Trends of Changes on Characteristics of Production and Destruction Processes of lake Sevan. In: Limnology of Mountain Water Bodies // Yerevan, 1984, pp. 227–228 (in Russian).
5 6. Meshkova T. Current Status of Plankton of Lake Sevan (in Connection with the Descent of the Latter) // Proceed. of Sevan Hydrob. Station, 17, Yerevan, 1962, pp.15 88 (in Russian). 7. Parparov A. Primary Production and Chlorophyll a Content in Phytoplankton of Lake Sevan // Ecology of Lake Sevan hydrobionts, 17, 1979, Yerevan, pp. 89 99 (in Russian). 8. Legovich N. Changes in the Qualitative Composition of the Phytoplankton of Lake Sevan under the Influence of its Level Descent // Biological J. of Armenia, 21 (12), 1968, pp. 31–42 (in Russian). 9. Kazaryan A. Materials for Investigation Phytoplankton in lake Sevan // Ecology of hydrobionts of lake Sevan, 17, Yerevan, 1979, pp. 75 89(in Armenian). 10. Mnatsakanyan A. Changes in Species Composition and Biomass of Phytoplankton in Lake Sevan. In: Limnology of High Mountain Lakes // Yerevan, 1984, pp.172–173 (in Armenian). 11. Hambaryan L . Phytoplankton Succession During the Period of Level Re lowering of Lake Sevan // PhD thesis abstract, Yerevan, 2001, 21 pp. (in Armenian). 12. Abakumov V. Manual on the Methods for Hydrobiological Analysis of Surface Water and Bottom Sediments // “Hydrometeoizdat”, Leningrad, 1983, pp. 79–91 (in Russian). 13. Sudnitsina D. Algae Ecology of Pskov Region // Training manual, Moscow, 2005, 892 pp. (in Russian). 14. Proshkina–Lavrenko A., Makarova I. Algae of the Caspian Sea // “Nauka”, Leningrad, 1968, 346 pp. (in Russian). 15. Tsarenko P. A Guide to Chlorococcus Algae of the Ukrainian SSR // “Naukova Dumka”, Kiev, 1990, 206 pp. (in Russian). 16. Kiselev I., Zinova A., Kursanov L. A Determinant of Lower Plants. Algae, 2 // Moscow. 1953, 280 pp. (in Russian). 17. Heinz Streble , Das Leben im Wassertropfen // “Kosmos”, Stuttgard, 2001, 566 pp. 18. Han Maosen Shu Yunfang Atlas of Freshwater Biota in China // “China Ocean Press”, Beijing, 1995, 129 pp. 19. Makrushin A. Biological Analysis of Water Quality // “Nauka”, Leningrad, 1974, 59 pp. (in Russian). 20. Dulepov V., Leskova O., Majorov I. Systematic Ecology On line: http://abc.vvsu.ru/Books/sistemnaja_ekologija_up/page0031.asp., pp.31 35. 21. Barinova S., Medvedeva L . Atlas of the Algal Indicators of Saprobity (Russian Far East) // “Dalnauka”, Vladivostok, 1996, 365 pp. (in Russian). 22. Vasileva Kralina I . Composition and Dynamics of Algae of Yakutsk and its Surroundings (Middle Flow of r.Lena) // Algology, v.7, № 1, 1997, pp.30 34 (in Russian). 23. Startseva N. Phytoplankton Community Composition and Structure of Floodplain Lakes in Several Cultural landscapes’ (Example: Nizhnij Novgorod city) // Biology of Internal Waters, 2, 2001, pp.70 76 (in Russian).
6 24. Hovsepyan A. Some Features of Phytoplankton Growth in Lake Sevan in 2010 // Materials of Intern. Scientific Conference, Rotov na Donu, 2012, pp.177 180 (in Russian). 25. Vladimirova K. Phytoplankton of Lake Sevan // Proceedings of Sevan Hydrobiol. Station, v. 9, Yerevan, 1947, pp. 69 145 (in Russian). 26. Stroykina V. Phytoplankton of Lake Sevan Pelagic Water // Proceed. of Sevan Hydrobiol. Station, v. XIII. 1952, Yerevan, pp. 171 212 (in Russiian). 27. Nikulina V., Mnatsakanyan T. Phytoplankton of Lake Sevan During 1979 1981. In: Experimental and field Investigations of Hydrobionts of Lake Sevan. // Yerevan, 1984, pp. 18 43 (in Russian). 28. Mikaelyan A. Allogenic Succession in the Phytoplankton Community of Lake Sevan // PhD Thesis Abstract, Yerevan, 1996, 30 pp. (in Russian). 29. Hovsepyan A., Hambaryan L., Gusev E . Algal Communities of Lake Sevan. In: Ecology of Lake Sevan in the Period of Increase of its Level // Makhachkala ,2010, pp. 90 104 (in Russian). 30. Hovsepyan A., Gulanyan V., Hambaryan L. Investigation of Phytoplankton Community of Lake Sevan Main Tributaries // Bioogical J. of Armenia, 3 4, Yerevan, 2011, pp. 59 66 (in Armenian). 31. Khachikyan T., Hambaryan L., Hovhannisyan R. and Mkrtchyan Zh . Seasonal Dynamics of Phytoplankton Community of Lake Sevan Main Tributaries // Biological J. of Armenia, 63 (4), Yerevan, 2011, pp. 78 82 (in Armenian). 32. Khudoyan A . Phytoplankton of the Main Tributaries of Lake Sevan // PhD thesis, Moscow, 1994, 121 pp. (in Russian).
ОСОБЕННОСТИ КАЧЕСТВЕННОЙ СТРУКТУРЫ ФИТОПЛАНКТОННОГО СООБЩЕСТВА ОЗЕРА СЕВАН И ЕГО ВОДОСБОРНОГО БАССЕЙНА
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Одной из причин антропогенного эвтрофирования озера Севан является увеличение загрязнения водосборного бассейна. Для характеристики современного экологического состояния озера Севан и его водосборного бассейна были проведены исследования фитопланктонного сообщества с целью выявить сходство в качественном составе водорослей в основных притоках и в самом озере по индексу сходства Жаккара, а также показать возможное влияние качественных показателей рек водосборного бассейна на формирование флористического состава фитопланктона в озере.
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Table 1. The taxonomic composition of algae of Lake Sevan and its main tributaries
Phylum Class Order Family Genus Species
Bacillariophyta 2 4 12 28 93 Chlorophyta 2 6 14 16 33 Cyanophyta 2 3 7 10 25 Euglenophyta 1 1 1 2 5 Xantophyta 1 1 1 1 1 Total 8 15 34 57 157
8 Table 2. Ecological and geographical characteristics of phytoplankton in Lake Sevan and its major tributaries [21]
чи Characteristics of
species r.Agra r. Lichk r. Lichk r. Masrik r. Masrik r.Makenis r.Makenis r. Vardenis r.Vardenis r. r. Agrichi R. Dzknaget Dzknaget R. Major Sevan Sevan Major Minor Sevan Minor Sevan r.. Gavaraget
N n N n N n N n N n N n N n N n N n N n Geographical location Cosmopolites 28 46.6 21 44.6 18 45 18 42.9 22 3.0 21 35.6 16 47.1 12 40.0 20 37.0 20 42.9 Arcto-alpine 1 1.6 2 4.3 2 5 2 4.8 4 5.6 4 6.8 1 2.9 3 10.0 3 5.6 3 4.8 Boreals 8 13.3 5 10.6 6 15 6 14.2 14 19.7 12 20.3 6 17.6 4 13.3 7 13.0 13 20.6 Less studied 23 38.3 19 40.4 14 35 16 38.0 31 4.7 22 37.3 11 32.4 11 36.7 24 44.4 27 42.9
Saprobity Xenosaprobs 1 1.7 1 2.1 2 5 1 2.4 2 2.8 2 3.5 1 2.9 2 6.6 2 3.7 1 1.6 Xeno-oligosaprobs 1 1.7 - - 1 2.5 1 2.4 3 4.2 2 3.5 1 2.9 1 3.3 2 3.7 2 3.2 Xeno-β- - - 1 2.1 ------mesosaprobes Oligosaprobes 2 3.3 1 2.1 1 2.5 1 2.4 2 2.8 - - 2 5.8 2 6.6 3 5.6 2 3.2 Oligo-β- 4 6.6 5 10.6 3 7.5 3 7.1 6 8.4 6 10.5 3 8.8 3 10.0 4 7.4 6 9.5 mesosaprobes β-mesosaprobes 20 33.3 12 25.5 18 45.0 17 40.5 26 36.6 24 42.0 12 35.2 13 43.3 19 35.2 21 33.3 β-о-mesosaprobes 1 1.7 2 4.2 1 2.5 1 2.4 1 1.4 1 1.7 2 5.8 - - 1 1.9 2 3.2 β-α-mesosaprobes 1 1.7 1 2.1 2 5.0 - - 5 7.0 1 1.7 1 2.9 - - 2 3.7 2 3.2 α-β mesosaprobes ------1 1.6 α-mesosaprobes 3 5 3 6.4 3 7.5 2 4.8 7 9.8 6 10.5 4 11.8 3 10.0 2 3.7 7 11.1 Evrisaprobes 1 1.7 - - 1 2.5 1 2.4 1 1.4 - - - - 1 3.3 1 1.9 2 3.2 Less studied 26 43.3 21 44.6 8 20.0 15 35.7 18 25.3 15 26.3 8 23.5 5 16.6 18 33.3 17 27.0
N – number of species, n - % from the total amount of species
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Table 3. The generality of phytoplankton species of Lake Sevan and its main tributaries according to Jaccard index
Spe- Small r.Gavara r.Dzkna- Big r.Masrik r.Make r.Arpa r.Varde r.Argi r.Lichk cies Sevan get get Sevan nis nis chi
N 60 40 43 47 71 59 34 30 54 63 c - 19 19 - 18 18 16 14 18 21 k - 19.0 18.4 - 15.3 17.9 19.8 18.1 17.8 19.0
N – total amount of species, c – number of species , which are common to both sites , k – Jaccard’s coefficient .
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