Spatio-temporal distribution of zooplankton inhabiting Nile River in Qena Governorate, Egypt using Geomatics approach

Abstract

Zooplankton play a crucial role in aquatic ecosystems by serving as a key food source for larger marine and freshwater organisms, thus supporting the food web. They also act as indicators of water quality and environmental changes, aiding in the assessment of ecosystem health. This study investigates the spatio-temporal variability of zooplankton populations inhabiting the Nile River and its tributaries in Qena governorate, Egypt using a geomatics approach. It also assesses and analyze the relationship between environmental variables and zooplankton distribution focusing on four major groups: Cladocera, Copepoda, Rotifera, and Ostracoda. Samples were collected monthly from September 2020 to August 2021 at 15 sites. Seasonal patterns revealed distinct variations in abundance among these groups. In total, 46 zooplankton species were collected; most of them belong to cladocerans (23 species) and copepods (12 species). Cladocera exhibited peak abundance in winter (4936 individuals) and autumn (2252 individuals), suggesting favorable conditions in these seasons. Copepoda showed increased abundance in winter (1359 individuals) and autumn (508 individuals), with a marked decline in spring. Rotifera were most abundant in winter (333 individuals), with minimal presence in summer and spring. Ostracoda maintained consistently low abundance throughout the year, with slight increases in autumn and spring. The analysis of zooplankton diversity indices showed that species richness was highest in summer (1.01) and lowest in winter (0.71). Species evenness peaked in autumn (9.79) and spring (7.88), while Simpson diversity and Shannon-Wiener diversity were highest in autumn and spring, reflecting a well-balanced and diverse community during these periods. Winter showed a noticeable decline in diversity and richness. Correlation and regression analyses revealed that temperature negatively impacts the abundance of Cladocera and Copepoda, while higher salinity (TDS and conductivity) tends to favor Cladocera and Copepoda. Turbidity and pH showed limited influence on zooplankton abundance. These findings highlight the significant role of environmental factors, particularly temperature and salinity, in shaping zooplankton communities inhabiting the Nile River and its canals in Qena, providing insights into the dynamics of aquatic ecosystems and the effects of seasonal and environmental changes.