Physiological changes in the Cattle Egret, Bubulcus ibis, as a bioindicator of air pollution in New Damietta City, Egypt

Abstract

Different heavy metals accumulate in the environment due to intensive human activities, which adversely affect wildlife. Biota usually develops different biological responses to face such stress; analysis of these biological responses could be used as a biomarker of pollutants. The current study aimed to compare hematologic and biochemical parameters in cattle egret collected from industrial and rural sites in New Damietta City, Egypt, to assess the effect of heavy metal pollution. Selected heavy metals concentrations including copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), arsenic (As), and mercury (Hg) were measured for the two sampling sites in aerosols from ambient air, feathers, and blood samples. Some hematological, biochemical parameters and oxidative stress markers were measured in the blood using a non-invasive method. Sampling was done in summer and winter during 2015-2016. Heavy metal concentrations in aerosols from the industrial area were significantly higher than those from the rural site. The highest concentrations of all heavy metals in both sites were recorded in summer. Cattle egret from the industrial area showed a significantly decreased RBCs count and PCV level and increased WBCs count, total protein, albumin, triglycerides, uric acid, ammonia, creatinine, bilirubin, and cortisol levels. Moreover, birds from the industrial area suffered from environmental stress as indicated by elevations of MDA, GPx and catalase activity in industrial birds as compared to rural birds. In conclusion, birds from the industrial areas were adversely affected by the elevated concentrations of selected heavy metals, so it could be used as an effective bioindicator of environmental contamination.