Purpose
Using a combination of the geographical information system (GIS) and the Canadian water quality index (WQI), the current study sought to provide a long-term general assessment of the water ...quality of the Shatt Al-Arab River (SAAR), focusing on its suitability for living organisms. Likewise, SPSS statistics was used to develop a nonlinear WQI regression model for the study area.
Design/methodology/approach
The study required four decades of data collection on some environmental characteristics of river water. After that, calculate the WQI and conduct the spatial analysis. Eight variables in total, including water temperature, dissolved oxygen, potential hydrogen ions, electrical conductivity (EC), biological oxygen demand, turbidity, nitrate and phosphate, were chosen to calculate the WQI.
Findings
Throughout the study periods, the WQI values varied from 55.2 to 79.83, falling into the categories of four (marginal) and three (fair), with the sixth period (2007–2008) showing the most decline. The present research demonstrated that the high concentration of phosphates, the high EC values, and minor changes in the other environmental factors are the major causes of the decline in water quality. The variations in ecological variables' overlap are a senior contributor to changes in water quality in general. Notably, using GIS in conjunction with the WQI has shown to be very effective in reducing the time and effort spent on investigating water quality while obtaining precise findings and information at the lowest possible expense. Calibration and validation of the developed model showed that this model had a perfect estimate of the WQI value. Due to its flexibility and impartiality, this study recommends using the proposed model to estimate and predict the WQI in the study area.
Originality/value
Even though the water quality of the SAAR has been the subject of numerous studies, this is the only long-term investigation that has been done to evaluate and predict its water quality.
The present study has examined the spatiotemporal varieties of the demographics of the Shatt Al-Arab River fishes and their relation to some ecological components. The aim is to forecast these groups ...in the unexplored parts of the waterway with an emphasis on environmental indices of diversity. Three sites in the river were selected as an observation and study of these species, which lasted from March 2019 to February 2020, the study dealt with factors affecting fishes, as Water Temperature (WT), Dissolved Oxygen (DO), Potential Hydrogen Ion (pH), Salinity (Sal), and Transparency (Tra). Gill nets, cast nets, hooks, and hand nets were adopted to collecting fish. The results indicated that the fish population comprises 60 species representing 13 orders, 28 families, all species belonged to Osteichthyes except for one (Carcharhinus leucas) which belonged to Chondrichthyes. Cyprinidae is the prevalent family embraced by nine species. WT (12.1- 33.4°C) has a considerable influence on the total number of species and individuals to the north of the watercourse. However, salinity (0.9- 8.7 mg/L) was regarded as the essential impact on the composition, distribution, and abundance of species in the rest sites. Planiliza abu was the most abundant species attaining 20.21%, followed by Oreochromis aureus (16.41%), and Carassius auratus ranked (15.92%), the dominance (D3) value was 52.54%. The results of the current study showed that most of the diversity index values are considered a moderate status. On the other hand, the majority of the richness index values are viewed as semi disturbed status in all stations, while most of the values recorded of the evenness index are deemed as semi-balanced status. The application of GIS technique by using the ordinary kriging method showed high efficiency in the Shatt Al-Arab River. Therefore, this technique can be employed in environmental studies of fishes.
The larvae of Coptodon zillii were surveyed in Shatt Al-Arab River and East Hammar marsh from January 2015 to December 2015. A total of 127 C. zillii larvae were collected from three stations. The ...highest number of C. zillii larvae was 78 recorded at station 1 in East Hammar marsh (Mansoury), comprised 61.41% of the total fish larvae collected, and the lowest number (23) was from station 3 in Shatt Al-Arab River near Abu Al-Khaseeb, comprised 18.11% of the total fish larvae collected. C. zillii larvae were found in the study regions from April to October. The peak of abundance was 22.8 larvae/10m² during July at station 1. The lower abundance of larvae was 0.7 larvae/10m² in June at station 2 at the confluence of the Garmat Ali River with Shatt Al-Arab River. Water temperatures in the three sampling stations were similar and ranged from 12°C in December to 32 °C in July. Salinity in station 1 ranged from 1.2‰ in August to 2‰ in June while in station 2 it ranged from 1.03‰ in October to 2.8‰ in July and in the station 3 ranged from 2.7‰ in April to 6.1‰ in December during the study period. Positive correlation was shown between water temperature and salinity in all stations with the number and abundance of C. zillii larvae. The results indicated that the Shatt Al-Arab River and East Hammar marsh are spawning grounds for this species.
Objective: To study spatial and temporal variability of fish assemblage in the Shatt Al-Arab River. Methods: This study was conducted from December 2011 to November 2012. Water temperature, salinity, ...dissolved oxygen and transparency were measured from three sites in the river. Several fishing methods were adopted to collect fish including gill nets, cast net, electro-fishing and hook and lines. Associations between the distribution of fish species and the environmental variables were quantified by using canonical correspondence analysis. Results: The results showed that the fish assemblage consisted of 58 species representing 46 genera and 27 families belong to Osteichthyes except one (Carcharhinus leucas) relate to Chondrichthyes. Number of species increased in summer and autumn months and sharply decreased in winter. Tenualosa ilisha was the most abundant species comprising 27.4% of the catch, followed by Carassius auratus (23.7%) and Liza klunzingeri (10.6%). The dominance (D sub(3)) value for the main three abundant species was 61.7%. Nine species were caught for the first times from the river include eight marine. The overall values of diversity index ranged from 0.67 in March to 2.57 in October, richness index from 2.64 in January to 3.71 in September and evenness index from 0.22 in March to 0.73 in August. Conclusions: Spatially, the fish assemblages of Shatt Al-Arab River can be divided into three ecological fish guilds, namely, common species, seasonal species and occasional species.
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