Spatial Variation in Phytoplankton Diversity in the Sabarmati River At
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Kumar et al., Annals of Environmental Science / 2012 Vol 6, 13-28 SPATIAL VARIATION IN of phytoplankton. The calculated Palmer’s values of sites 1 to 3 were 16, 35 and 41 respectively. Shannon- PHYTOPLANKTON DIVERSITY Weaver species diversity index (H’) values for the IN THE SABARMATI RIVER AT three sites were S1: 2.04; S2:1.41; and S3: 1.16. The Nygaard’s indices value showed oligotrophic nature of AHMEDABAD, GUJARAT, INDIA the water at S-1, while a eutrophic nature of fresh 1,* 1 water was observed at S-2 and S-3. Rita. N. Kumar, Rajal Solanki and Nirmal 2 J.I. Kumar Keywords: Phytoplankton, Sabarmati River, Diversity Index, water pollution 1 Department of Biological & Environmental Sciences, N.V. Patel College of Pure & Applied Sciences, Vallabh Vidyanagar. 1. INTRODUCTION 2 P.G. Department of Environmental Science and Technology, Institute of Science & Technology for Phytoplankton abundance in a water body reflects the Advanced Studies & Research (ISTAR), Vallabh average ecological condition and, therefore, it may be Vidyanagar – 388 120, Gujarat, India. used as an indicator of water quality [1,2]. In natural waters such as oceans, lakes, rivers and swamps, the Received February 7, 2012; in final form May 21, greatest amount of biological production is due to the 2012; accepted May 23, 2012 smallest organisms, namely the plankton. These microscopic plants comprise communities that drift aimlessly with tides and currents, yet they incorporate ABSTRACT and transfer large amounts of energy that they pass on to higher trophic levels. Thus communities of Biological assessment is a useful alternative for rating plankton, as distinct from those of swamp, forest, or the ecological quality of aquatic ecosystems since grassland, support other communities of aquatic biological communities integrate the environmental species and man [3]. effects of water chemistry. Phytoplankton are assem- Population pressure, urbanization, industrializ- blages of heterogeneous microscopic algal forms ation and increased agricultural activity have whose movement is more or less dependent upon significantly contributed to the pollution and toxicity water currents. To know the nature of species of aquatic ecosystems. Pollutants bring about a change composition of phytoplankton and their significance, not only in the physical and chemical quality of water the present observations were made for a period of but also modify the biotic components, resulting in the twelve months in the Sabarmati River, Ahmedabad, elimination of some probably valuable species. India from three selected sites, i.e. upstream (site 1), Chemical analyses of water provide a good indication midstream (site 2) and downstream (site 3). The study of the quality of aquatic systems, but they do not revealed the occurrence of 48 species of phyto- integrate ecological factors such as altered riparian plankton; among these, 21 species of Chlorophyceae, vegetation or altered flow regimes and, therefore, do 13 species of Bacillariophyceae, 11 species of Cyano- not necessarily reflect the ecological state of the phyceae and 3 species of Euglenophyceae were system [4]. Biological assessment is a useful altern- recorded. The algal flora of polluted water bodies ative for assigning the ecological quality of aquatic showed the dominance of blue green algae and ecosystems since biological communities integrate the diatoms like Oscillatoria, Anabaena, Microcystis, environmental effects of water chemistry in addition Navicula, Nitzschia, Synedra, Gomphonema through- to the physical and geomorphological characteristics out the investigation. Many green algae like Eudorina, of rivers and lakes [5]. Scenedesmus, Stigeoclonium and Ankistrodesmus also The Sabarmati River is one of the four major occurred abundantly and frequently. Various indices rivers that traverse the alluvial plains of Gujarat. It rises in the Aravalli hills at a North latitude of 24 o40’ such as Palmer’s, Nygaard’s and Shannon’s biotic o indices have been used for the assessment of diversity and East longitude of 73 20’ in Rajasthan State at an elevation of 762 meters above mean sea level. The river is known to be under contamination menace by * Corresponding author phone +91 98259 24687; e-mail: [email protected]; [email protected]; wastes derived from industrial sources, sewage and www.rnkumar.co.in; www.ritankumar.co.in. agricultural activities that alter the physico-chemical www.aes.northeastern.edu, ISSN 1939-2621 13 Kumar et al., Annals of Environmental Science / 2012 Vol 6, 13-28 and biological properties and ecology of the biotic Sites 2 and 3. It includes river dredging, construction environment. Therefore, the present study is an of retaining walls, ghats, promenades, etc. These attempt to record the changes in the community activities result in the influx of soil, cement and other structure of phytoplankton in the Sabarmati River, a particulate matter in the river, which affects the backbone of Ahmedabad city, from upstream to quality of the water and in turn leads to alteration in downstream in response to the changing physico- the plankton community. The water samples for chemical environment. physico-chemical and plankton analysis were collected on a monthly basis for the calendar year 2010-11. 2. MATERIALS AND METHODS 2.3. Physico-chemical analysis 2.1. Study area The water quality parameters such as temperature, pH Ahmedabad is located at 23.03°N and 72.58°E at an and Dissolved Oxygen (DO) were measured in situ. average elevation of 53 meters above mean sea level Temperature was measured with a mercury-filled and spans an area of 310 km ². The Sabarmati River glass thermometer, pH with an EiE Instrument ATC enters Ahmedabad near Hansol and passes through the model 132E pH meter and DO by the Winkler center of the city with a stretch of approximately 20- method. Other parameters, namely alkalinity, chloride, 25 km from north to south. phosphate, sulfate and nitrate were measured in the laboratory with standard methods for the examination of water and wastewater [6,7]. 2.4. Phytoplankton Analysis The phytoplankton samples were collected using a 20µ mesh size planktonic net from approx. 1 m depth of the water column and were preserved in 4% formalin for further analysis. The water samples were allowed to sediment for microscopic identification of plankton. For quantitative analysis, one drop of sample was taken on a clean glass slide and phyto- plankton were counted by Lackey’s drop count method, in which the coverslip was placed over a drop of water on the slide and the whole of the coverslip was examined by parallel overlapping strips to count all the organisms in the drop. About 20 strips were examined in each drop. The number of subsamples to Figure 1 Site map of the study area be taken depended on examining 2 to 3 successive subsamples without any addition of unencountered 2.2. Sabarmati River species when compared to the already examined subsamples [6]. The results obtained are expressed as Three sites, namely Site-1 upstream - Indira Bridge number of organisms per Liter of sample. The (23 o5’26”N and 72 o37’47”E), Site-2 midstream- o o phytoplanktons analyzed were assigned to major Gandhi Bridge (23 2’24”N and 72 34’24”E) and Site- groups, namely green algae (Chlorophyta), blue green 3 downstream - Sardar Patel Bridge (23 o0’40”N and o algae (Cyanophyta), diatoms (Bacillariophyta) and 72 34’27”E) have been selected for the present work Euglenophyta. (Figure 1). The identification of phytoplankta was carried out Site 1 is situated outside the main city near with the help of standard books and monographs [8- Kotarpur Village and is surrounded by agricultural 10]. Biodiversity indices were calculated using fields, whereas Sites 2 and 3 are situated in the main Palmer’s algal index [11], Nygaard’s trophic state city area and are approximately 4.5 km and 9 km indices [12] and the Shannon-Weaver diversity index away from Site 1, respectively. The work on the to know the diversity of phytoplankton and pollution Sabarmati River Front Development is at a fast pace at status of the Sabarmati River. 14 www.aes.northeastern.edu, ISSN 1939-2621 Kumar et al., Annals of Environmental Science / 2012 Vol 6, 13-28 Correlation coefficients (r) were calculated for early rain [15]. The elevated levels of nitrogen can phytoplankton density in relation to hydrochemical cause eutrophication, which is observed in many parameters using the Ky Plot Beta 2.0 version. shallow patches near the river bank [16]. Construction of reservoirs and dams also contributes to eutrophication as they decrease the flow velocities 3. RESULTS within a river [17]. The correlation coefficient of physico-chemical 3.1. Water Quality Parameters parameters and phytoplankton is summarized in Table 2. Analysis of the important parameters with the The average hydrochemical properties of water are phytoplankton density showed a positive correlation given in Table 1. The surface water temperature of of temperature with Cyanophyceae (r = 0.957), Sites 1-3 ranged between 18 oC to 24oC. The Bacillariophyceae (r = 0.904) and Euglenophyceae (r temperature showed a gradual increase from the = 0.496), and DO with Cyanophyceae (r = 0.394) and month of March till the onset of the monsoon season Bacilariophyceae (r = 0.799). However, DO showed in July and gradually decreased from the rainy season negative correlation with Euglenophyceae (r = -0.96). to the post-monsoon months. The DO and pH of the Oxidation of organic matter brings down the water showed a highly positive correlation in river concentration of DO in water. Euglenophytes water (r = 0.860). The DO in the river water showed proliferate in environments poor in oxygen [18]. marked variation at different sites. The DO value at Furthermore, sulfate showed a positive correlation upstream S-1 ranged from 5 mg L -1 to 7.7 mg L -1 in with Cyanophyceae (r = 0.371) and Euglenophyceae (r the months of July and January, respectively.