Evaluation of lead exposure effects on tissue accumulation, behavior, morphological and hemato-biochemical changes in common carp, Cyprinus carpio

Background: Heavy metal pollution, particularly lead (Pb), poses a significant threat to aquatic ecosystems and their inhabitants, threatening their delicate balance and long-term viability. This study highlights the urgent need to mitigate heavy metal pollution in aquatic ecosystems.

Objective: This study investigates Pb(NO₃)₂ exposure effects on tissue accumulation, behavioral abnormalities, and hemato-biochemical parameters in common carp (Cyprinus carpio), a widely distributed freshwater fish species.

Methodology: Fish (115 ± 5.23 g) were exposed to various Pb(NO₃)₂ concentrations for 10 and 20 days, representing control (0 %), 25 %, 50 %, and 75 % of the LC₅₀ equivalent to 19.33, 38.66, and 58.0 mg/l, respectively. The standard manual procedure was used for blood sampling. The lead concentration in fish tissue was determined using an atomic absorption spectrophotometer.

Results: Results revealed that fish gills showed significant (P < 0.05) increase in Pb(NO₃)₂ after 10 days, further rising after 20 days. Liver concentrations also rose significantly (P < 0.05) with prolonged exposure and increasing Pb levels. Muscle had lower concentrations. Hematological parameters (RBC, WBC, HB, HCT) decreased with higher Pb(NO₃)₂ levels. Behavioral and morphological changes were significantly more pronounced in the exposure groups when compared to the control group. Hepatic enzyme activities (AST, ALT), glucose, and lipid levels increased, while total protein decreased.

Conclusions: The study highlights Pb(NO₃)₂ harmful effects on common carp, impacting tissue accumulation, hematological parameters, and biochemical disruptions. It emphasizes the need to monitor and mitigate heavy metal pollution in aquatic environments to safeguard freshwater organisms and ecosystems, and to further increase our understanding of Pb toxicity in freshwater ecosystems.