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Impact of Al-Rasheed Power Plant Effluents on Phytoplankton Biodiversity in Tigris River, Southern Baghdad

The objective of the current study was to evaluate the effects of Al-Rasheed Power Plant(RPP) effluents on biodiversity of phytoplankton. Samples were collected monthly from January to December 2012, at four sites that were selected on the Tigris River at Baghdad Province. Site 1 was located at the up of RPP, sites 3,4 were located at the down of RPP, while site 2 was located near RPP. The results shown that the total number of the phytoplankton range from 51.7 - 9146.89 cell * 103/L, which was recorded at site1 and 3, respectively, with average range from1486.68-2053.27 which was recorded at site 1and 4, respectively. According to the relative abundance index all species where rare, except Cyclotella sp. were less abundant species. The Species richness, Shannon Winner and uniformity index values were ranging from 3.71-21.12, 0.3-3.28 bit/Ind. and 0.13 -0.71 at site 2 and 3 respectively, whereas the average value for same index was from 12.42-15.15 at 2 and 1 site; 1.93- 2.34bit/Ind. at 2 and 3 site, and 0.52-0.62 at 2and 4 site, respectively. Generally the result showed a negative effect of thermal effluent on biodiversity and phytoplankton community. Also, the water of Tigris River was considered a poor diversity and polluted especially at site 2.


Introduction
Water pollution is a major problem, as all water resources are exposed to pollution because they are exposed to many human residues, industrial and agricultural uses, making the world increasingly interested in water resources and how to address the pollution that has occurred [1]. These ecosystems are suitable habitats for the growth of different species, since any change in their properties affects the growth and diversity of aquatic organisms and is greatly affected by plankton, especially phytoplankton, which are very sensitive to change in the aquatic environment, which affects their composition and thus affects the rest of the aquatic communities in the food chain [2; 3], as phytoplankton and aquatic plants are the basic base of the aquatic food web and any undesirable change in water properties negatively affects them and this indirectly affects on community structure of higher trophic levels [4], the quantity and quality of phytoplankton and its biological diversity have been shown to be adversely affected by liquid residues posed to aquatic systems, causing low biomass and total productivity [5; 6; 7; 8] One of the influencing factors in the survival and diversity of the phytoplankton community in the aquatic environment is warm water which considered to be a liquid thermal waste and significant impact in the water temperature [9]. Also Krishnakumar et al. [10] indicated that the life aquatic environment is threatened by any changes in the water characteristics resulting from exposure to severe heated water which affecting in primary products. Also the liquid of electric power plants effluents causing a change in physical and chemical properties such as viscosity, surface tension, gases solubility and nutrient, as well as they affect significantly on the aquatic biological system and on the all levels of the food chain. Starting from the change in the composition, total number, diversity and productivity of the phytoplankton community [11].
The impact of the power plant effluents on aquatic life has been studied by many researchers, including the study of these effects on bacteria [12; 13], phytoplankton [14; 15] and zooplankton [16] also, studies were emphases on the impact of electrical power plant effluents on biomass and productivity of phytoplankton that result from the rise in temperature [3; 17; 18] while Muhammad et al. [19] studied the effects of the power plant on the abundance and structure of the species, noting that the waste of power plants has adverse effects on the plankton community, showing a decrease in biomass and total productivity through the use of some bio indicators. Also Lo et al. [20] studied the effect of thermal effluents on the phytoplankton communities before, after and near the power plant effluents and they noted that a low of total number of phytoplankton near effluent site. Studies on the impact of Iraqi power stations are limited, including: Nashaat [21] conducted a study for impact of Al-Durah power plant effluents on physical, chemical and invertebrate biodiversity in the Tigris River, southern Baghdad. While Hassan et al. [22] study of impact of electric power plant effluents on the physical and chemical properties of water, the total density of phytoplankton and the composition of its species in the waters of the Shatt Al-Basra and the Shatt al-Arab on the effect of liquid effluents of the Hartha and the Nangibia power plants. However, Nashaat et al. [23] assesses the impact of Al-Rasheed power plant effluents on rotifera biodiversity at Tigris River, Southern Baghdad. While Muhammad et al. [19] studied the impact of Musayyib power plant effluents on the Euphrates River properties which shows a change in all water properties that return to its value before the power plant as we move away from the site of discharge as a result of dilution. Nashaat et al. [24] conducted a study on the impact of Al-Rasheed power plant effluents on cladocera fauna biodiversity in the Tigris River, Southern Baghdad, whereas Nashaat et al. [25] studied the impact of Al-Rasheed power plant effluents on biodiversity of benthic fauna in Tigris River. The impact of same power plant effluents on the occurrence and composition of Copepodes in Tigris River was conducted by Nashaat et al. [26], and on the some ecological characteristics of Tigris River [27], also Al-Azawii, et al. [28] assessing the effects of it on the quality of the Tigris River, by using the Canadian Water Quality Index (CCME WQI). From the literature cited above, It's appear limited work were done on the effects of the power plant (heat waste effluent) discharged into phytoplankton assemblage. Therefore, this project was undertaken to a study the impact of Al-Rasheed power plant (RPP) effluents on phytoplankton biodiversity in Tigris River.

Materials and Methods
To achieve such this study, samples were collected monthly for the duration from January to December 2012 of four sites were identified as follows ( Figure.  4-Site 4 (S4): was located about 2 Km after site 3.

Samples Collection
Monthly, water samples were collected from the four sites for a whole year from the center of the river at a depth of 30 cm from the surface by 1L polyethylene bottles for the quantitative study of phytoplankton, as the method described by Hadi [29], then the sample was preserved with Lugol solution and concentrated by the  31]. and was examined under a compound microscope (40X for Nondiatom and 100X for Diatom) finally the species was diagnosed depending on the following diagnostic keys [29, 32; 33; 34; 35] then the results expressed as cell*10 3 /L. While biodiversity indicators are calculated according to the mathematical formulas as described below, which are presented in the following references 1-Relative abundance Index: depending on Tyler [36].

Results and Discussion
The results showed that the highest value of the total phytoplankton number was recorded at site 1 during August, which was 9146.89 cells/L * 10 3 and the lowest number was recorded at station 2, which was 51.7 cell/L*10 3 during November, with averages of 1940.49, 1486.68, 1542.9 and 2053.27 cell/ L was recorded for the four study sites respectively (Table 1 and Figure 2). It was noticed two peaks of the total phytoplankton number, the first in the spring and the second in the autumn, according to the differences in the total number of phytoplankton which may be due to the change in the physical and chemical factors of water that may occur as a result of the change in the water level and RPP effluents [41], or may be to the suitable temperatures at spring and autumn for growth, reproduction and blooming of phytoplankton during this season [42].
The study also recorded a highest number at site 1 and the lowest at site 2 which correspond to the findings of Lo et al. [20] this may be due to the impact of the RPP effluents, Moreover, it was also noticed that this value was returned gradually to the reference values when we stay away from the RPP effluents as a result of dilution, this is consistent with Hassan et al. [22].  Figure 2. Variation of total phytoplankton number. Concerning on a Relative abundance Index and constancy index (Tables 2) it was showed that Cycllotalla ocellata was recorded less abundant (La) while the other species were rare(R) to appear in all stations, which indicates a sensitivity of these species for all changes in water properties caused by the RPP effluents.
According to the constancy index most of the species were accidently and few were accessory species except Cyclotella meneghinia, C. ocellata, Cocconeis spp., Diatoma, Navicula spp. and Nitzschia palea that considered a constant species at all the studied sits which might be able of all these constant species to be overcome against that extreme conditions. More constant and persistent species are characterized by a wide range of tolerances for change in environmental conditions [43]. This was noted by Kadem [44] Kassim et al. [45]. Table 2. Relative abundance and constancy frequencies index of phytoplankton species identified in the study area.
Moving to species richness index, It was recorded the highest value of the species richness index was 21.12 at site 3 and at least 3.71 at site 2 with averages of 15.15, 12.42, 13.98 and 13.49 for the four sites respectively (Table 1and Figure 3). It was observed from the results that there was a variation in the values of this index between sites and seasons, which may be due mainly to the variation in the total number of phytoplankton during the duration of the study, abundance and the degree of water pollution [46] especially at site 2, and also depend on the change by RPP in the water temperature degree, which is one of the factors influencing in the increasing or decreasing of the number of phytoplankton and the lack of primary productivity [47]. Regarding Shannon-Weiner Diversity Index, results for phytoplankton diversity hit its peak at 3.28 bit/Ind. at site 3,whaeras, the lowest of which was 0.3 bit/Ind. that recorded at site 2, with average of this index was 2.14, 1.93, 2.27 and 2.34 bit/Ind. at all sites, respectively (Table 1and Figure 4).  Figure 4. Variation of phytoplankton Shanon-Weiner Diversity Index . The Shannon-Weiner Index is a guide to water quality and pollution. When its value is less than one, it indicates severe environmental pressures, as follows [48]:-More than 3 bit/Ind. indicates a high biodiversity and clean water, 3-1bit/Ind. indicates a moderate pollution, less than 1 bit/Ind. indicates a highly polluted environment that causes death or migration of sensitive species. So it was revealed that from Shannon-Weiner index results that Tigris River water is moderately polluted except second site, which was highly pollution especially in August and this may be the result of the impact of the RPP effluents. Our results match with Dimitrova et al. [49] which indicated that lack of diversity is associated with increased pollution, also confirmed by Salmen and Nassar [50] whom indicated that increase in organic pollution due to the supply of sewage and the impact of human and industrial residues causes a lack of biological diversity. However, this result was in line with the study of Muhammad et al. [19].
Moving to the Species Uniformity Index (Evenness), site 2 have shown the lowest values in the phytoplankton species uniformity index, which were 0.13, while the highest values was 0.79, which were recorded at site 3, also all sites was recorded averages of this index was 0.54, zero, 50, 0.62 and 0.62 respectively (Table 1 and Figure 5). It's noted from the Uniformity Index results that these species are under high environmental pressure, because the values did not exceed 0.5 especially at site 2 which it located near RPP during different months. Thus, these species are considered non-uniform in its appearance and its distribution across the species [51]. Low Uniformity Index values demonstrate that dominance of few species with high densities due to the environmental pressure as Green [52] suggested. The values of this indicator range from 0-1; as low values to one or more, species have a strong impact on the ecosystem, while higher values indicate equal abundance of each species [51] whereas the proximity of individual density to each other  [53], However, the results of this study were similar to the results of Kadem [44], which recorded values ranging from 0.8-0.2 4.Conclusions: it is clear from the findings of the study that the RPP effluents affected negatively on the phytoplankton community of Tigris River and its biodiversity, by causing a decreasing in total numbers and a lack of biodiversity, also the river water is moderately to highly polluted, especially at the second site, which located directly on the influence of RPP effluents and decreases gradually it affect at third and fourth site as a result of the dilution process.