Using Immobilized Algae (Scenendesmus quadricauda) to Reduce Copper Element Toxicity in Common Carp Fish (Cyprinus carpio)

The study assessed the efficiency of immobilized algae (Scenedesmus quadricauda (Turpin) Brébisson) in treating copper toxicity in common carp fish. Acute toxicity of copper towards carp fish was determined. Fish were exposed in aqueous tanks to different heavy metal concentrations (10, 15, 25, and 35 ppm) for 96 h to examine their response. The lethal concentration (LC50) of copper for common carp over 96 h was found to be 1.4 ppm, with fish mortality increasing gradually with higher metal concentrations. Subsequently, half of the LC50 concentration (0.7 ppm) was used as a chronic toxicity concentration, and fish were treated for 21 days to assess copper accumulation in their gills and muscles. Copper concentration in gills on day 5 of the experiment was 16.89 ± 2.2 mg.kg-1 (Mean ± S.D), a significant increase from in muscles, which recorded 10.72 ± 1.1 mg.kg-1 (Mean ± S.D). On day 21, the copper concentration decreased significantly in both gills (4.73 ± 0.5 mg.kg-1) and muscles (8.4 ± 4.5 mg.kg-1) compared to the control group (significant LSD 0.05). But the copper and algae group recorded on day 21 of the experiment (a significant decrease LSD 0.05) in both the gills (mg.kg-1) Mean± S.D) (4.73±0.5) and the muscles (mg.kg-1) Mean± S.D) (8.4±4.5) compared to the copper group. The removal rate in the gills was 75.57%, and in the muscles was 21.17%. Therefore, treatment with immobilized algae is an efficient and promising method for treating copper toxicity in aquatic environments.