Scanning Electron Microscopy Unveils Profenofos as a Critical Stressor on the Gills of Channa gachua (Hamilton, 1822)

Aims: The widespread use of Profenofos, an organophosphate pesticide, in agriculture, has raised concerns about its ecotoxicological effects on aquatic ecosystems. This study investigates the impact of Profenofos on the gill morphology of Channa gachua, a freshwater fish species, using scanning electron microscopy (SEM) to elucidate ultrastructural changes.

Study Design: Healthy specimens of Channa gachua (dwarf snakehead) were collected from local freshwater bodies. The average length and weight of the fish were 12–15 cm and 20–25 g, respectively. Channa gachua specimens were exposed to sublethal concentrations of Profenofos (0.5 mg/L and 1.0 mg/L and 2.0 mg/L) for 21 days, and gill tissues were subsequently analyzed to assess morphological alterations.

Methodology: Channa gachua were exposed to sublethal Profenofos concentrations (0.5mg/L, 1mg/L and 2 mg/L) for 21 days. Gill tissues were dissected, fixed in 2.5% glutaraldehyde, and dehydrated using an ethanol series. The samples were critical-point dried, gold-coated, and analyzed using scanning electron microscopy (SEM) to assess ultrastructural changes. Morphological alterations, including epithelial lifting, lamellar fusion, and mucus secretion, were quantified. Statistical analysis compared damage severity between control and treated groups. Results confirmed Profenofos as a critical stressor, highlighting its detrimental effects on gill ultrastructure.

Results: SEM analysis revealed significant Profenofos-induced damage to the gill architecture of Channa gachua. Key observations included the distortion of primary and secondary lamellae, epithelial lifting, and rupture of microbridges. These structural deformities were dose-dependent, with higher concentrations of Profenofos causing more severe damage. The fusion of lamellae and epithelial lifting was particularly pronounced, suggesting impaired respiratory and osmoregulatory functions. Additionally, the presence of mucus secretion and cellular debris on the gill surface indicated a stress response to the toxicant. The ultrastructural changes observed in this study highlight the detrimental effects of Profenofos on gill tissue, which could compromise the fish's ability to maintain physiological homeostasis. The damage to the gill epithelium likely hinders oxygen exchange and ion regulation, potentially leading to hypoxemia and osmoregulatory imbalance. These findings underscore the role of Profenofos as a critical stressor in aquatic environments, with implications for the health and survival of fish populations.

Conclusion: This study provides compelling SEM-based evidence of Profenofos-induced gill pathology in Channa gachua, emphasizing the need for stricter regulation of organophosphate pesticides to protect aquatic biodiversity. The results contribute to a deeper understanding of the ecotoxicological impacts of Profenofos and highlight the importance of using advanced imaging techniques like SEM to assess environmental stressors on aquatic organisms’ invasive independent predictors for screening esophageal varices may decrease medical as well as financial burden, hence improving the management of cirrhotic patients. These predictors, however, need further work to validate reliability.