Ecological studies of three West Algerian rivers: The Habra reservoir and the Mactaa canal.

Abstract

Limnological studies of Habra Watershed were carried out on aquatic bodies of the coastal north-west Algeria. The Habra-Sigg (Habra Watershed) forms a large basin in which two sampling sites were chosen, the Mactaa Canal, a canal with connections to the sea and the Habra Reservoir. Samples were taken monthly for two years (1986-1988). Air temperatures were ranged from 14°C to 31°C and water temperatures from 10°C to 30°C. Fluctuations at Mactaa Canal were more than those of Habra Reservoir regarding hydrogen ion concentration (6.8-8.1), oxygen percentage saturation (54-125), biological oxygen demand (0.8-11.8mg l-1), total residue (3.39-25.3 mg l-1), volatile matter (1.03-16.95 mg l-1), chloride (1.35-10.40g l-1), ammonium-nitrogen (5.2-26.3 μg l-1) and silicate-silicon (1.8-5.1mg l-1), whereas fluctuations were similar for current velocity (CV), water turbidity (50-95mgl-1), electrical conductivity (2.6-10.22mScm-2), dissolved oxygen (4.8-11.8 mg l-1), suspended solids (20.4-84.5mg l-1), dissolved organic matter (3.53-21.76 PV(4h)mg l-1), fixed total residue (2.65-12.49 mgl-1), nitrite-nitrogen (0.07-1.03 mg l-1), nitrate-nitrogen (3.1-8.6 mgl-1) and phosphate-phosphorus (1.1-7.2mg l-1). Magnesium hardness at Habra Reservoir (1.70 mg l-1 as CaCO3) and at Mactaa Canal (1.57 mg l-1 as CaCO3). Calcium hardness and total hardness values were similar at both sites (0.7 and 2.4 mg l-1 as CaCO3 respectively).