Assessment of effects of metal contamination and abiotic factors on fatty acid composition and biochemical biomarkers activity in the liver of Chelon ramada collected from two ecosystems on the Mahdia coast, Tunisia

Abstract

This study aimed to assess metal contamination and abiotic factors during spring and autumn in two ecosystems, the open Sea area (S1) and the fishing harbor (S2), located on the Mahdia coast (Tunisia) using the thin-lipped grey mullet, Chelon ramada, as a bioindicator, with the main objectives of evaluating the relationship and combined effects of these parameters on liver fatty acid composition and relevant malondialdehyde (MDA), catalase (CAT), and acetylcholinesterase (AChE) activity, informing on the pollution status in these ecosystems for appropriate management procedures, and validating the use of C. ramada as a bioindicator for contamination assessment programs in Tunisia. The results revealed a significant increase in Pb, Cu, Zn, and Cd concentration in sediments, water, and liver at S2 during spring. In addition, significant variations in temperature and salinity were observed between S1 and S2 during spring and autumn. Moreover, a significant high increase in saturated stearic acid (SFA-C18:0) and both polyunsaturated arachidonic (ARA, C20:4n-6) and eicosapentaenoic (EPA, C20:5n-3) acids at S2 during autumn and spring, respectively. Furthermore, significant high activity was found at S2 in both MDA and CAT during spring and in AChE during autumn. Accordingly, the S2 ecosystem appeared more contaminated than S1, but the impacts of contamination during autumn were mitigated by significantly higher temperature and salinity. These findings provide important information for environmental assessment programs in Tunisia and should help formulate more stringent management procedures for the discharges of the harbor, shipping, fishing, and industrial activities into the ecosystem of Mahdia fishing harbor (S2).