Impact of some environmental parameters on phytoplankton diversity in the eastern Al-Hammer marsh / southern Iraq

: Biodiversity is one of the important biological factors in determining water quality and maintaining the ecological balance. In this study, there are 223 species of phytoplankton were identified, and they are as follows : 88 species of Bacillariophyta and were at 44%,70 species of Chlorophyta and they were at 29 %, 39 species of Cyanophyta and they were at 16 %, 12 species of Euglenozoa and they were at 4 %, four species of Miozoa and they were at 3 %, and, Phylum Charophyta and Ochrophyta were only eight and two species, respectively and both of them were at 2%. The common phytoplankton recorded in the sites studied include Nitzschia palea , Scenedesmus quadricauda , Oscillatoria princeps , and Peridinium bipes , These species recorded a significant positive correlation with Ec, Sio3, and WT. Phytoplankton including Gomphosphaeria semen - Vitis , Dicloster acuatus , Tetrastrum heteracanthum , and Dictyocha fibula , recorded a significant positive correlation with NO3, PO4, DO, and PH. Water temperature ranged between 14.200 -33.900 ºc in Al-Mansoury and Al-Sada respectively. Electrical conductivity ranged between 2.790 - 11.900 ms/cm in Al-Sada and Al-Mansoury respectively. PH ranged between7.750-8.600 in Al-Dawody and Al-Mansoury respectively. Dissolved Oxygen (DO) ranged between 5.950 -13.000 mg/l in Al-Dawody and Al-Mansoury respectively.WT recorded negative correlation with pH (r= - 0.591), NO3 -2 (r= - 0.463) and DO (r= - 0.603). Nitrate ranged between 0.570-12.200 µg /l in Al-and Al-Sada respectively. Phosphate ranged between 0.003-0.154 µg/l, in Al-Dawody and Al-Mansoury respectively. Silicate ranged between 51.200-198.600 µg /l in Al-Baraka and Al-Dawody respectively. Shannon - Weiner index (H`) ranged between 2.275-3.162 in Al-Dawody and Al-Mansoury respectively. Simpson index ranged between 0.856-0.950 in Al-Mansoury and Al-Sada respectively, while the Evenness index was 0.514-0.933 in Al-Dawody and Al-Baraka respectively. Shannon-Weiner index (H`) recorded a significant positive correlation with the Simpson index .


Introduction:
Aquatic ecosystems are the main sources of the continuance of life for most organisms that live in the aquatic system 1 . Phytoplankton is the primary producers and significant source of nutrients in an aquatic ecosystem as they involve in the biogeochemical cycles of several elements to supply heterotrophic organisms with organic material. They are the essential biological characteristic that regulates productivity and nutrient cycling within food webs and carbon usage, along with water quality in determining the water ecosystems' ecological state. Phytoplankton availability is 40% of the world's primary production, and it is the foundation of the aquatic food chain 2,3 . Due to minor changes in nutrients and their brief life cycle, Phytoplankton reacts swiftly to environmental changes 4,5 . Changes in hydro-climatic, biological, and chemical factors of the aquatic ecosystem have affected the distribution and abundance of Phytoplankton communities which indicate the water quality 6 . Since Phytoplankton communities are generally more sensitive to pollution, therefore, they are the best biotic indicators of pollution in the aquatic habitat 7 .
The study of the environment of the marshes was stopped for a long time due to the drying of the marshes 1990-2003, but after the rehabilitation of the Al-Hammer marsh there are not enough studies of the phytoplankton diversity in the Eastern Al-Hammer marsh, however, there are many studies covered physical and chemical factors and primary production. This study came to diagnose phytoplankton and the accompanying qualitative changes after drying and flooding, as in this study new species that are not registered in the Iraqi environment were recorded 8 . Some of these studies include limnological studies of traits of Al-Hammar marsh after restoration 9 , which studied 10 Al-Hammar marsh after the flood; studied 11 evaluating water quality of Al-Hammar marsh with the GIS technique; studied 12 using indicators based on satellite images to evaluate the restoration plan for Al-Hammar marsh. Studied 13 Carlson's Trophic State Index. Following a significant rise in salinity over the 2018 summer, studied 14 the Eastern Al-Hammar marsh's Water Quality Index (WQI) was used as an indication and studied 15 of the primary productivity of phytoplankton in the southern marshes of Iraq. There are recent studies in the other marshes of Iraq, and some studies showed the phytoplankton diversity in the different marshes of Iraq and 16, 17 studied phytoplankton diversity in Auda marsh and studied 18 the effect of physical and chemical factors in the water of the Chabayish marsh.
This work aimed to study the phytoplankton diversity in the Eastern Al-Hammer marsh as well as aquatic environmental factors after it flooded in 2003, whereby the traits of its ecosystem have changed.

Materials and Methods: Study area
In southern Iraq, there are a lot of marshes, permanent ones and seasonal ones, but the significant marshes are that three marshes act as Iraq's wetlands: Marsh of Al-Hammar, Hawizeh marsh, and the central marshes 19 . The Iraqi marshes have changed significantly during the past 40 years for many reasons, such as drying and constructing dams, etc., which resulted in changing several of its traits, flooded areas, environmental system, and biological diversity composition 20 .
East Al-Hammer marsh Fig. 1 acts as part of the South Al-marshes. It stretches for more than 33 kilometers, with the maximum deep water extent of 1.00 -6.00 meters, depending on the tide. During the conditions in the 1990s, the marsh was exposed to desiccating. The marsh flooded in 2003 and recovered its vegetation and wildlife to varying degrees 31 . The study was continued from December 2019 to November 2020, Phytoplankton was collected from four different sites by net (Al-Sada, Al-Mansoury, Al-Dawody, and Al-Baraka), Al-Sada site (N″ 30˚37.24.2 E″ 47˚40. 07.7) is a far 6 km away from the Karma Bridge. The depth is approximately 6 m, it contains animals, birds, and Crustaceans, as well as various fishing operations, fishing Fish, shrimp, and birds that were recently damaged due to the progression of the saline tongue. Al-Mansoury site (N″30˚40.31.4 E″47˚37. 22.9') is a distance from the site. Al-Sada is about 2 km away, and it is less area than the Al-Baraka site, but it is deeper than that and characterized this area is elongated in shape and called channel marsh, which contains branches and fish farms on the edges. It is one of the large marshes that are called Openness marsh. Al-Dawody site (N″ 30˚41.30.5 E″ 47˚35. 52.1 )'is a narrow water channel of less depth, the height of the muddy land on two sides, the presence of many aquatic plants and the presence several different birds on the site Al-Baraka site (N″ 30˚41.47.8' E″ 47˚32. 59. 6) is an open and shallow area. The depth does not exceed three meters; it reaches its depth of 0.5m on the Islands. It is a far 13 km from the first station and much aquatic life, fish, shrimp, and many types of birds, reptiles, and mammals are inhabited it. Field and laboratory study water temperature (ºC), electrical conductivity (EC) and pH were measured monthly using TRI METER (PH/EC-983) and DO determine by using an Oxygen meter (WTW). Nitrate, phosphate and silica were calculated based on 21 . The phytoplankton samples for this study were collected using a net of the size of about 20µm, we throw the net into the water and pulled it at a proper speed for 15 minutes, then collect the contents in the polyethylene bottle is clean and fixation in the field using formalin solution with a concentration of % 4 . For microscope research and species identification, all organic material in diatom and silico-flagellate frustules must be oxidized and removed so that the valve structure can be observed. The frustules were cleaned in this study by boiling them in hydrogen peroxide. The 10 mL diatom suspension was heated for 30-45 minutes in 20 mL 30 % H2O2 or until the suspension became transparent 22 10 ml. The diatom suspension was allowed to settle at room temperature before being washed four times with distilled water and filtered using Whatman No. 1 filter paper to eliminate all organic contaminants permanent slides were made using Naphrax®. Algae morphology was screened (400x magnification). The Haemocytometer technique was used to count the non-diatom algae 23 . One drop of the sample was placed on a glass slide, covered with a glass cover slip, and viewed under a microscope with magnification 40x. using a microscope digital camera (SCMOS03000KPA) and cell dimension (diameter, length, and width) of investigated algae, and algae were diagnosed based on the results 24-26 .

Figure 1. A map of sample collection sites from East Al-Hammer marsh, South of Iraq
Shannon -Weiner diversity index (H`): 27 index value was calculated by using the formula.* H` =-pilnpi Where, 'pi' equal ni/N ni: is the number of individuals in each species N: the total number of individuals in the sample Simpson's diversity index(D): 28 This index represents the abundance ratio of individual species to that of total* abundance values. It was calculated using the following formula D = 1/ pi 2 pi: is the preparation of the species to total abundance value.

Results and Discussion:
Values of physical-chemical parameters showed variations in the current study among four sites over ten months. WT ranged from 14.200 °c in Al-Mansoury during January and 33.900 °c in Al-Sada during July, while ranging between 15.100-32.900°c in Al-Baraka and Al-Dawody respectively.WT recorded no Significant differences in all sites p >0.05. some species appeared in the hot months such as Nitzschia palea, and Oscillatoria princeps, and some species appeared in the cold months such as Gomphosphaeria semen-vitis, Dicloster acuatus because WT is important for the physiology, behavior, distribution, survival, growth, and reproduction processes 31,32 . The solubility of gases and salts in water is influenced by temperature, this is a confirmed negative correlation between WT and DO (r= -0.603) which is a significant component. Higher Electrical conductivity values of 11.900 ms/cm were observed in Al-Mansoury during May and a lower value of 2.790 ms/cm was observed in Al-Sada during November while ranging between 2.990 -11.400 ms/cm in Al-Baraka and Al-Dawody respectively due to decreased water discharges from Tigris and Euphrates and water entry from Arabian gulf across Shatt Al-Arab 33,34 . EC recorded Significant differences in all sites p < 0.05, most diatom species recorded in the current study adapted to be found in saline and brackish water 35 .EC showed significant negative correlation with NO3 (r= -0.328) this agree with [33][34][35][36] Table 1. Higher pH values of 8.600 were observed in Al-Mansoury during January and a lower value of 7.750 was observed in Al-Dawody during July while ranging between 7.840 -8.530 in Al-Sada and Al-Baraka respectively. Increasing in pH may be the increase in the density of phytoplankton, the increase in the process of photosynthesis for algae and aquatic plants, and an increase in the consumption of carbon dioxide according to to 6,37 . This confirmed a significant positive correlation between PH and DO (r=0.630). Higher Dissolved Oxygen values13.000 mg/l were observed in Al-Mansoury during January and a lower value of 5.95 mg/l was observed in Al-Dawody during July while ranging between 7.540 -11.800 mg/l in Al-Sada and Al-Baraka respectively, the low values for (DO) in the hot months return to high temperatures and salinity 38 as well as an increase in activity organisms (bacteria) that decompose organic matter and consume oxygen, higher values for (DO) may be to increased photosynthesis rates by phytoplankton and aquatic plants, as well as a larger surface water area that allows for better mixing and oxygen compensation from the atmosphere 38 , the current study agreed with the studies 36,39 .
The maximum reactive Nitrate was 14.730 µg /l in Al-Sada in December, and the slightest in Al-Dawody 0.570 µg /l in August while ranging between 0.800 -11.740 µg /l in Al-Baraka and Al-Mansoury respectively. NO3 recorded Significant differences in all sites p < 0.05 .The maximum reactive phosphate was 0.154 µg /l in Al-Dawody in January slightest in Al-Mansoury 0.003 µg /l in May while ranging between 0.004 -0.141 µg /l in Al-Sada and Al-Baraka respectively, whereas the maximum reactive silicate 198.60 µg /l in Al-Baraka in July and lowest in Al-Dawody 51.200 µg /l in February while ranged between 61.6 -174.6 µg /l in Al-Mansoury and Al-Sada respectively, Sio3 showed a significant positive correlation with Wt (r=0.630). Po4 and sio3 recorded no Significant differences in all sites p >0.05 these results agreed with 36 . In addition to the release of silica from sediments or the decomposition of diatom cells 40 , these nutrients are rapidly eaten by the aquatic plants growing in the marsh. Phosphate (PO4) and nitrate NO3 concentrations were low 10 . Phytoplankton production is influenced by nitrogen, phosphorus, and inorganic phosphate. They respond quickly to the environment, disagreeing due to delicate nutrient alterations and their short life cycle 41,42 . The growth of phytoplankton lowers the levels of micronutrients in the surface layers, such as nitrates, phosphates, and silicates, and limits primary production. This, too, is largely influenced by local weather conditions and topography 43 .
Phytoplankton identified approximately 223 taxa belonging to 93 genera, Bacillariophyta represented the highest percentage 44% belonging to 88 taxa,41 genera, they respond quickly to changes in the environment 44 the common genera Nitzschia 13 species and was one of common genera found at all sites due to the large range of environmental tolerance 45   The second group, Chlorophyta 29 %, belongs to 70 taxa, and 27 genera. The common genera are Scenedesmus 17 species; Cosmarium seven species, Oocystis and Tetraedron, found with six species for both, Pediastrum five species Crucigenia and Ankistrodesmus, found with four species for both, The other groups were Cyanophyta 16 % belonging to 39 species 15 genera, common genera that Oscillatoria eight species. Chroococcus six species, Merismopedia and Gomphosphaeria found with four species for both, Anabaenopsis and Spirulina found with two species for both and recorded only one species for Komvophoron minutum, Pseudanabaena galeata. Euglenozoa 4% belonging to 12 species three, common genera that Euglena eight species and was from the common species, Phacus three species and recorded only one species for Lepocinclis glabr, Miozoa(3%)belonging to four species three genera, common genera that Peridinium two species., recorded only one species for, Glenodinium armatum, Noctiluca scintillans Table. 2.
The correlation between the common species and environmental parameters at all sites was studied using (CCA) N. palea distributed evenly in sites of the current study and has a strong positive correlation between EC, silicate, and WT. On the other hand, this species shows a strong negative correlation with NO3, PO4, and pH because a plateful of Silicate makes diatoms take NO3 and PO4 at a much faster rate to build their cellular materials 51 Fig 3. S.quadricauda has a strong positive correlation with NO3 and EC because can be grown in a great range of brackish or saline water 52 . O. princeps has a strong positive correlation with PO4 and PH, and a moderate positive correlation with NO3 because these factors are responsible for the growth 53 . On the other hand, this species includes a strong negative correlation with EC.

E.
Proxima recorded a significant positive correlation with PH and WT agreement with 18 . P. bipes distributed evenly in sites of the current study and showed a significant positive correlation with pH, NO3, and PO4 and showed a negative correlation with WT and EC. This indicates that the WT, pH, EC, nutrient nitrogen and phosphor play a pivotal role in the productivity and community structure of phytoplankton 6,54 . phytoplankton recorded during intermittent periods include Gomphosphaeria semen-vitis, Dicloster acuatus, Tetrastrum heteracanthum, and Dictyocha fibula have a strong positive correlation with NO3and PO4 because these nutrients limiting factors for the growth of phytoplankton. On the other hand, these species include a strong negative correlation with WT and EC, WT is important for the physiology, behavior, distribution, survival, growth, and reproduction processes 31,32 . The Shannon diversity indicator is widely used to determine diversity that considers both the number and evenness of species in a community. It is a number that ranges from 0 to 4. The Shannon index (H`) for phytoplankton was found to be the highest in Al-Dawody in May at 3.162 and indicates (less pollution) and lowest in Al-Mansoury in October at 2.275 indicate (more pollution) according to 55  The marsh has suffered from drying. As a result, the characteristics of its ecosystem have changed, and all its organisms have been affected, including algae. Other researchers noticed the phytoplankton species composition reaction to reflooding 17 . After 2003, uncontrolled releases of Tigris and Euphrates River waters partially recovered some old marsh areas in southern Iraq, but restoration in others is failing due to the excessive soil and water salt concentrations 57 .