Microplastic Contamination in Four Carnivorous Cultrinae Fish in Dianshan Lake, China

Microplastic (MPs) contamination in freshwater ecosystems threatens aquatic biodiversity. We investigated MPs ingestion in four sympatric Cultrinae fish species from Dianshan Lake, China, using gastrointestinal tract and stable isotope analyses. MPs were widespread, but abundance was low (1.25 ± 2.36 items/ind.). Fibers dominated and consisted mainly of polyethylene terephthalate and polyester, likely derived from fishing gear and domestic laundry. Cultrichthys erythropterus showed the broadest trophic niche and highest MPs diversity, suggesting that opportunistic feeding increases exposure to diverse polymers. MPs abundance was not related to trophic position (Cultrichthys erythropterus: P = 0.24; Culter dabryi: P = 0.07; Culter mongolicus: P = 0.09; Culter alburnus: P = 0.77), providing no evidence of biomagnification among the examined Cultrinae species. However, MPs abundance was negatively correlated with condition index in three species, but not in Culter alburnus. These findings suggest that trophic niche width may be more closely associated with MPs exposure than trophic position within the examined fish assemblage.