Effects of Physicochemical Factors on Seasonal Variations of Phytoplankton in the Mond River Estuary of Bushehr Province, Persian Gulf, Iran
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BIODIVERSITAS ISSN: 1412-033X Volume 18, Number 1, January 2017 E-ISSN: 2085-4722 Pages: 229-237 DOI: 10.13057/biodiv/d180130 Effects of physicochemical factors on seasonal variations of phytoplankton in the Mond River Estuary of Bushehr Province, Persian Gulf, Iran MOJTABA POULADI1,♥, AMIR QADERMARZI1,♥♥, FATEMEH BAHARVAND2, AMIR VAZIRIZADEH3, ALIAKBAR HEDAYATII 1Department of Fisheries, Faculty of Fisheries and Environmental Sciences, Agriculture and Natural Resources University of Gorgan, Gorgan, Iran, Tel.: +98-9173742476, ♥email: [email protected], ♥♥email: [email protected] 2Faculty of Environment, Islamic Azad University, Arak Branch, Arak, Iran 3Department of Marine Biology and Fisheries, Persian Gulf Research Institute, Persian Gulf University, Bushehr, Iran Manuscript received: 7 December 2016. Revision accepted: 20 December 2016. Abstract. Pouladi M, Qadermarzi A, Baharvand F, Vazirizadeh A, Hedayati A. 2017. Effects of physicochemical factors on seasonal variations of phytoplankton in the Mond River Estuary of Bushehr Province, Persian Gulf, Iran. Biodiversitas 18: 229-237. The main purpose of present study was to investigate the abundance and biodiversity of phytoplankton from Mond estuary, Bushehr, Persian Gulf during different seasons and its relationships with environmental parameters and nutrients. Samples were taken in mid-season from spring 2012 to winter 2013 for oneyear period. The phytoplankton were contributed by the phyla Bacillariophyta, Dinophyta, Haptophyta, and Chlorophyta. The class Coscinodiscophyceae and Bacillariophyceae belonging to Bacillariophyta were the most diverse and dominant with 22 and 16 genera, respectively. The mean phytoplankton abundance were recorded in spring (12706.7±3586.9 cells L-1), in summer (10173.3±2560.08 cells L-1), in autumn (10600±2758.2 cells L-1) and in winter (7000±2401.6 cells L-1), respectively. Simpson and Shannon-Wiener biodiversity indices obtained showed in spring (0.93±0.007 and 3.8±0.2), in summer (0.92±0.008 and 3.64±0.2), in autumn (0.92±0.006 and 3.63±0.15) and in winter (0.89±0.013 and 3.07±0.24), respectively. The phytoplankton assemblages were most diverse and abundant at station-5 in all seasons. In addition, there were significant correlation (P<0.01) between phytoplankton abundance and diversity with pH, salinity, NO3, PO4 and temperature. Based on Principle Component Analysis (PCA), the most important factors that could describe most changes of abundance and diversity of phytoplankton in the Mond River estuary system were salinity, NO3, pH, PO4 and temperature, respectively. Results demonstrated that diatoms were the dominant population and salinity factor was more effective factor that affected the diversity and abundance of phytoplankton during study period in Mond River estuary. Keywords: Abundance, Bushehr, diversity, Mond River Estuary, phytoplankton, Persian Gulf INTRODUCTION phytoplankton and other organisms. The abundance of phytoplankton are biological indicators for evaluating Estuaries are dynamic transition zones between the water quality and the degree of eutrophication (Chaturvedi continental and the marine ecosystems that are et al. 1999; Ponmanickam et al. 2007; Shekhar et al. 2008). characterized by their high primary and secondary levels There have been very few studies on the seasonal and and ecological complexity (Attrill and Rundle 2002; Lam- annual variation of phytoplankton in Iranian estuaries, Hoai et al. 2006; Matos et al. 2011). In these transitional which indicate that the environmental management can be ecosystems, fluctuations in environmental variables have a limited by the relating to how the physical and chemical direct effect on the dynamics of biological populations, in factors influence the phytoplankton seasonal patterns in particular the plankton community (Marques et al. 2006; estuaries. In addition, few long-term observations on the Matos et al. 2011). Estuaries provide nursery habitat for phytoplankton assemblages have been carried out in the fish, birds and many other organisms (Calbet et al. 2001). Iranian waters of the Persian Gulf (Seraji and Daghoughi These ecosystems encompass one of the most productive 2000; Fallahi 2003; Fatemi et al. 2012; Isapour et al. 2012; ecosystems around the world (Day et al. 1989). In the Aein Jamshid et al. 2014; Shapoori and Golami 2014). estuarine planktonic biota, the phytoplankton deserves Saraji and Daghoughi (2000) observed 35-40 phytoplankton special attention due to their fundamental role in the genera in the coastal waters of west, central and east of primary production of coastal environment (Gross and Hormozgan; Fallahi (2003) observed diatoms were Gross 1996; Tiwari and Chauhan 2006; Tas and Gonulal dominant with 97 species in the waters of Bushehr in 2007; Saravanakumar et al. 2008). Increased human Persian Gulf; Isapour et al (2012) showed that diatoms activities, industrialization and urbanization have put lots were more abundant and specious at Khouzestan when of pressure on the estuarine habitat. These activities have compared with other groups at Bushehr and Hormozgan direct effect on the water quality, quantity and quality of areas; Shapoori and gholami (2014) observed that 230 BIODIVERSITAS 18 (1): 229-237, January 2017 Bacillariophyceae and Dinophyceae were the dominant phytoplankton abundance and diversity, and their groups of phytoplankton in the Kharg Island waters and ecological relationships with nutrients and water quality AeinJamshid et al (2014) observed that the high risk toxin parameters in the MR estuary, Bushehr, the northern part of producing Dinophyceae and Bacillariophyceae dominated Persian Gulf, Iran. at contributing to about 29.3% and 61.7% of the total phytoplankton, respectively. Mond estuary and river is the fifth river of Iran with MATERIALS AND METHODS 750 km estimated length. The Mond River (MR) originates from Fars Province and gets discharged in to the Persian Study area Gulf, passing through Jahrom, Firuzabaad in the Fars The study area was located in the Mond River estuary, province and Jam, Dashti and Dayyer in the Bushehr the southeastern part of Bushehr province, and north of province (Ahmadi et al. 2013). The MR basin is Persian Gulf, Iran (Figure 1). Along MR estuary, five ecologically important for migratory birds, wild life and sampling stations were determined based on environmental aquatic organisms, especially fish. Therefore, studying on gradients of flow dynamics and mixing of fresh and coastal the phytoplankton abundance, composition and diversity of waters, depth, tides, river flow and geo-morphological MR estuary is an important aspect for fishery management. features (Table 1). The main objective of this study was to determine the Figure 1. Sampling stations at the Mond River estuary, Persian Gulf, Iran POULADI et al. – Phytoplankton variations in the Mond River Estuary, Persian Gulf 231 Procedures diversity indices were calculated using Ecological Seasonal samplings were carried out in the middle of Methodology, version 6.0 (Krebs 2001). each season for one year period from May 2012 to February 2013.Water temperature and pH were recorded by Mercury thermometer and pH meter model WTW. Salinity RESULTS AND DISCUSSION was recorded with using Atago S/Mill refractometer. Dissolved oxygen was measured by YSI 51 Oxygenmeter During the present study, 4 phyla of phytoplankton (Model OH, USA) and transparency was obtained by communities were identified: Bacillariophyta, Dinophyta, Secchi depth plate .Water samples for measurement of Haptophyta, and Chlorophyta (Tables 2). Higher diversity nutrients were collected by Ruttner bottle (Hydro-Bios was observed from class Coscinodiscophyceae belonging Model) and were measured using HACH to phylum Bacillariophyta with 22 genera and 37 species, spectrophotometer (Model DR 4000). To investigate the and class Bacillariophyceae belong to phylum abundance and identification of phytoplankton Bacillariophyta with 16 genera and 18 species. assemblages, 3 liters of water were sampled with Ruttner Phytoplankton species including Coscinodiscus centralis, bottles and were immediately fixed using Lugol’s iodine Donkinia sp. and Pleurosigma cuspidatum belonging to the solution (10 ml per 200 ml of sample). These bottles were class Coscinodiscophyceae and phylum Bacillariophyta stored in a cool and dark place for transportation to the were observed during all seasons, but Skeletonema laboratory survey. Enumeration of phytoplankton were costatum, Odontella mobiliensis, Odontella sinensis, carried out using Sedgwick rafter chamber with the aid of Rhizosolenia bergonii, Rhizosoleina shurbsolei, inverted microscope (Model: CETI Belgium) and were Dactyliosolen fragilissimus, Chaetoceros compressus and identified using standard publications(Faust and Gulledge Chaetoceros peruvianus belonging to the class 2002; Newell and Newell 2004). Cosciodiscophyceae and Gyrosigma diminutum belonging The following formula was used to calculate the to the class Bacillariophyceae and phylum Bacillariophyta abundance of phytoplankton: showed lowest dispersion in MR estuary during the study period (Tables 2). The mean seasonal abundances of -1 phytoplankton are presented in Figure 2. Mean abundance C [cells L ] = -1 of phytoplankton were 12706.7±3586.9 cells L in spring, 10173.3±2560.08 cells L-1 in summer, 10600±2758.2 cells -l -l N= number of cells or units counted, A= area of field L in autumn and 7000±2401.6 cells L in winter, (mm2), D= depth of a field (Sedgwick-Rafter chamber respectively.