Microplastics (MPs) are pervasive contaminants in aquatic ecosystems, yet experimental evidence of their trophic transfer within tropical African food webs remains scarce. This study provides experimental evidence of indirect trophic transfer of microplastics from Artemia salina to Oreochromis urolepis, a cichlid species of ecological and economic importance in African inland and coastal waters. A simplified two-level food chain was established by exposing A. salina nauplii to fluorescent polyethylene microplastics (10–20 µm; 1, 10, and 100 mg L⁻¹) and subsequently feeding them to juvenile O. urolepis under controlled laboratory conditions. These concentrations were selected to represent a range of exposure levels commonly used in laboratory studies to assess concentration-dependent responses. Rapid uptake of MPs occurred in A. salina, with over 90% of nauplii ingesting particles within three hours. Fluorescent particles were subsequently detected in the intestinal tract of O. urolepis, confirming successful dietary transfer and revealing a clear concentration-dependent increase in MP occurrence and burden. Behavioral assessments following a 7-day dietary exposure showed only minor and non-significant effects on feeding latency, feeding success, and swimming activity, indicating limited short-term functional impairment under the tested conditions. Overall, these findings demonstrate that trophic transfer represents an efficient exposure pathway for microplastics in tropical fish and highlight the importance of incorporating dietary exposure and food-web interactions into microplastic risk assessments, particularly in African aquatic ecosystems where empirical data remain limited.
Dativa J. Shilla (Tue,) studied this question.