Bioaccumulation of heavy metals in an aquatic insect (Baetis pavidus; Baetidae; Ephemeroptera) in the El Harrach Wadi (Algeria)

Abstract

Baetis pavidus is considered the larva of aquatic insects belonging to the order Ephemeroptera. These ephemeral larvae measure 1 cm on average, and adults have a very short imaginal life. These ephemerals are a widely used biomonitoring tool; they are good indicators of water quality. In this study, we investigated the spatial variability in the bioaccumulation of four metallic trace elements (Hg, Pb, Cu, and Zn) in Baetis pavidus as a function of environmental parameters in the El Harrach Wadi, which crosses Algiers, the capital of Algeria. The sampling was carried out monthly over 13 months, from May 2011 to May 2012; ten (10) stations were selected along the Wadi, distributed between altitudes of 11 and 220 m. A variance analysis (ANOVA I) was carried out to study the spatial variability in the bioaccumulation of the trace elements in Baetis pavidus to determine whether heavy metal levels were significantly different between study stations. Significant correlations were recorded between concentrations of heavy metals in the water and water physicochemical parameters. In this study, the bioaccumulation of Hg and Pb varied significantly from upstream to downstream, but there was no significant difference in the bioaccumulation of Cu and Zn. Redundancy analysis (RDA) showed that the bioaccumulation of copper, zinc, and lead depended on the temperature of the water, calcium, and nitrates. The concentrations of mercury, lead, copper, and zinc accumulated in Baetis pavidus based on the environmental parameters, confirming strong contamination of the El Harrach Wadi water system by these four metallic trace elements.