First characterization and spatial distribution of microplastics in Sardina pilchardus fish gathered along the northern Tunisian coast

Abstract

The growing concern of microplastic (MP) accumulation in oceans presents a threat to marine life and ecosystems. The present study investigates the presence of MPs in Tunisia's most-consumed fish species, Sardina pilchardus, sampled from various sites along the northern Tunisian coast, including Tabarka, Bizerte, La Goulette, and Kelibia. From a total of 40 fish specimens examined (n = 10 per site), results revealed that 92.5 % had MPs in their digestive tracts, and 72.5 % had MPs in their gills. MP concentrations ranged from 1.1 ± 0.99 to 5.86 ± 3.39 particles per individual in the digestive tract and from 1.2 ± 2.25 to 4.00 ± 3.67 particles per individual in the gills. The highest MP concentrations were observed in sardines caught off the coast of Bizerte. MPs identified in three types as fibres, fragments, and films and in various colors, including black, clear, blue, red, green, and white. The majority of MPs found in both the digestive tract and gills were fibres. Additionally, the smallest size class (ranging from 0.033 to 0.5 mm) dominated in both tissues of the sardine. These findings raise concerns and serve as a reference point for understanding the extent of MP pollution along the northern coast of Tunisia. They also suggest considering sardines as potential bioindicators of marine plastic ingestion.