From urbanization to bioaccumulation: A comparative study of metal pollution and biomarker responses in Donax trunculus along a touristic coastal area in Morocco

Abstract

This paper examines the use of the edible bivalve, Donax trunculus, as a bioindicator of metal pollution (Cd, Pb, Cu, Zn, and Cr) resulting from beach urbanization related to touristic development in Morocco. The study aim is to conduct a two-year investigation to compare a period of moderate urbanization (2018) with a period of high urbanization (2019). Particularly, the study investigated the occurrence and bioaccumulation levels of metals in D. trunculus as well as the response of four biomarkers in this sentinel species. The results revealed that metal bioaccumulation in the studied bivalve increased due to the intensification of anthropogenic activities associated with urbanization, particularly for cadmium. Similar findings were observed for the metal pollution index, which reached higher values in the second year. Overall, the hazard associated with human consumption was not significant, however, the risk was more probable for children and during 2019. In the second year, the examined biological endpoints demonstrated varied responses, including induction for glutathione-S-transferase and malondialdehyde, inhibition for catalase, and stability in acetylcholinesterase activity. Consequently, statistical analyses revealed a relationship between the bioaccumulated metals and the response of biomarkers. Further management considerations are required in the study area to minimize the occurrence and the risks of metals. Likewise, additional in situ and ex situ scientific investigations must be implemented to provide deeper findings about the sources, occurrences, magnitudes, and toxicity of metals in the touristic coasts of Morocco.