Effects of chronic exposure to sediments from the Zarzis area, Gulf of Gabes, measured in the mussel (Mytilus spp.): a multi-biomarker approach involving oxidative stress and neurotoxicity

ABSTRACT

The hereby study was conducted to assess the chronic biological effects of potentially contaminated sediments collected at the Zarzis area, Tunisia, on the marine mussel species (Mytilus spp.). Useful information can be provided through the analysis of biomarkers that allow inferring about the presence of pollutants and their adverse effects, contributing for a better assessment of ecosystems' quality and functions. Three sampling sites were chosen taking into account the putative impact of different human activities at several sites located in Zarzis area, compared to an unpolluted reference site, located in Afurada, Vila Nova de Gaia, Portugal. Physical-chemical characterization involved the survey of metals (Cd, Cu, Cr, Hg, Zn and Pb) and polycyclic aromatic hydrocarbons (PAHs), whose toxic effects are involved in the onset of oxidative stress. Biomarkers involving oxidative stress and neurotoxicity were quantified in hemolymph, gills, and digestive gland tissues of Mytilus spp. following the chronic exposure to the distinct sediments. Organisms exposed to sediments collected at the Zarzis area presented the highest values of the tested oxidative stress biomarkers and a significant inhibition of AChE activity in comparison with the unpolluted reference site. This set of results suggests that biomarker responses representing different biological endpoints in Mytilus spp. are useful for the assessment of environmental pollution effects, namely by PAHs and metals. Our results suggest the presence of these chemicals in specific sampling sites whose sediment caused evident biological responses in mussels.

KEYWORDS:

• Mediterranean Sea
• pollution
• sediments
• mussels
• biochemical effects

Acknowledgments

We are grateful to the ‘Erasmus Mundus Programme’ for providing scholarship to R. Ghribi through the ‘Battuta’ program (Building Academic Ties towards Universities through Training Activities) dedicated to the development of relations between Europe and North Africa through grants of excellence between the two regions. The Tunisian Ministry of Higher Education and Scientific Research also supported this research study. This work was conducted in the framework of Researcher FCT Program (Operational Program for Human Potential, QREN, EU; IF/01744/2013) which hired Bruno Nunes. Thanks are also due to Fundação para a Ciência e a Tecnologia, namely to the project ECO-R-pharmplast - Ecotoxicity of realistic combinations of pharmaceutical drugs and microplastics in marine ecosystems”, (reference POCI-01-0145-FEDER-029203). The authors are particularly thankful to Prof. Abdelmajid Dammak for his contribution to correct grammatical errors and to improve the English writing skills of this paper. This research was also financially supported by CESAM (UIDB/50017/2020+UIDP/50017/2020), by FCT/MCTES through national funds (PIDDAC), and by the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. This research was supported by national funds through FCT – Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020.

Disclosure statement

The authors declare that they have no conflicting interests.