Doñana National Park survey using crayfish (Procambarus clarkii) as bioindicator: Esterase inhibition and pollutant levels

Utility of carboxylesterase and acetylcholinesterase inhibition as pesticide exposure biomarker was studied at Doñana National Park (SW Spain) in crayfish (Procambarus clarkii). Activities were measured in animals from reference sites or potentially exposed to pesticides, and their reactivation studied after dilution or 2-PAM treatment. Crayfish from affected sites had significantly less carboxylesterase and acetylcholinesterase activity than reference ones. No significant differences were found after dilution or 2-PAM treatment, showing that inhibition was irreversible. High pesticide levels were found in water and/or soil at rice growing sites, and lower levels at other affected places. High metal levels existed at rice growing sites and lower at other affected and at both reference sites. A combined effect on esterase inhibition of pesticides and metals is proposed. This field study suggest that the rice growing areas near Guadiamar stream are most polluted, followed by strawberry and citrics growing zones near Partido and Rocina streams. However, no correlation exist between the pesticide concentration at different sites and the extent of esterase inhibition, indicating that other factors could affect esterase response of animals from polluted sites.