Abstract
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.
Highlights
Shatt Al-Arab River is affected by the tidal phenomenon, so it is considered a critical transitional zone
Another reason is the deterioration of water quality due to exposure to industrial, agricultural waste, and sewage, which leads to the decay of the aquatic environment, and the entry, spread of invasive and alien species, all these problems produced a change in the composition of fish populations [4,5,6,7]
P. abu is considered a native species for a long-time in this area 18
Summary
Shatt Al-Arab River is affected by the tidal phenomenon, so it is considered a critical transitional zone. The decrease of flow from the Tigris and Euphrates rivers is the most important one, that is because the hydrological ventures, developed in neighboring nations and control of water sources coming across borders, led to the penetration of salt water wedge from the bay to the rivulet stream. Another reason is the deterioration of water quality due to exposure to industrial, agricultural waste, and sewage, which leads to the decay of the aquatic environment, and the entry, spread of invasive and alien species, all these problems produced a change in the composition of fish populations [4,5,6,7]. The principal dangers to biodiversity are the ecological variances, contamination, natural changes, and overexploit of the stocks, besides obtrusive species [8,9,10]
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