Effect of pollution on macrobenthic invertebrates in some localities along the River Nile at Great Cairo, Egypt

The impact of heavy metals on macrobenthic invertebrates in five stations along the River Nile at Great Cairo (from Helwan to El-Qanater El-Khiria) was studied during the period from May, 2013 to February, 2014. Physico-chemical characteristics and heavy metals (iron, manganese, zinc, copper and cadmium) were analyzed in water. The highest average number (2305 org./m²) of macrobenthic invertebrates was recorded during spring, while the lowest (642 org./m²) was recorded during summer. Annelida, Mollusca and Arthropoda were the most dominant groups being 62 %, 34 % and 4 % respectively. Twenty two species and taxa were recorded; Mollusca (13 species) and Annelida (7 species) Arthropoda (2 species). All the heavy metal concentrations were within the permissible limits except at Helwan and Hawamdia due to the effect of discharged industrial wastes. The highest positive correlation was recorded between Arthropoda and iron zinc, while iron recorded a negative correlation with Mollusca and Annelida. The principal component analysis (PCA) showed that the most dominant annelid Limnodrilus spp. had a positive correlation with cadmium and negative correlation with all other heavy metals. This indicates that this species can resist the high concentrations of cadmium.