Influence of soil and water physicochemical parameters on the biodiversity of nematodes and soil microarthropods near drainage canals in El Beheira Governorate, Egypt

The Nile Delta faces a critical challenge of environmental degradation due to the pollution of its soil and water from industrial and agricultural effluents. This study investigated the influence of soil and water physicochemical parameters, including heavy metal concentrations, on the biodiversity of nematodes and soil microarthropods near drainage canals in Egypt's El Beheira Governorate. Water and soil samples were collected from five sites in Kafr El-Dawar, El Delingat, Abo Hommos, El Mahmodia, and Nobaria and analyzed for macronutrients, pH, electric conductivity, and heavy metals (Zn, Cr, Al, Cd, Pb). The extracted nematode and microarthropod communities were identified and evaluated using diversity indices. The results revealed significant spatial variations in environmental conditions, with several water samples exceeding WHO/FAO safety limits for Cr, Cd, and Pb, while soil metal levels remained within safe thresholds. Multivariate analyses demonstrated that factors like salinity (EC, Na, Cl), pH, organic matter, and specific heavy metals were significant drivers of community structure. Sites with higher contamination, like Nobaria and El Mahmodia exhibited lower faunal diversity and dominance by tolerant species, while less polluted sites supported richer, more balanced communities. The findings conclusively demonstrate that nematode and microarthropod communities are highly sensitive bioindicators, effectively reflecting anthropogenic pollution stress and providing a valuable tool for monitoring ecological health in agricultural drainage ecosystems.