Habitat selection overrides trophic transfer: modeling microplastic ingestion in Mediterranean fish assemblages

Abstract Microplastic (MP) pollution has emerged as a major environmental concern in marine ecosystems, yet the ecological mechanisms governing MP ingestion in fish assemblages remain insufficiently quantified. This study investigated the relative influence of habitat preference, feeding behavior, trophic level, and biological traits on MP ingestion in 11 fish species ( N = 297) collected from the highly industrialized Iskenderun Bay, Northeastern Mediterranean Sea. Because MP abundance data exhibited substantial overdispersion, both Poisson and Negative Binomial Generalized Linear Models (GLMs) were evaluated, with the Negative Binomial framework demonstrating markedly superior performance based on the akaike information criterion (AIC) and dispersion diagnostics. The final model identified habitat-related exposure pathways as the dominant predictors of MP ingestion. Relative to the benthopelagic reference group, demersal species exhibited significantly higher expected MP abundance ( β = 0.99, p < 0.001), whereas pelagic-neritic species showed significantly lower MP loads ( β = − 1.13, p < 0.001). Gastrointestinal tract (GIT) weight was positively associated with MP abundance ( β = 0.16, p < 0.001), suggesting that anatomical retention capacity may influence particle accumulation. In contrast to conventional biomagnification expectations, the trophic level displayed a significant negative relationship with MP abundance ( β = − 0.47, p = 0.0047), indicating a potential trophic dilution pattern. Residual diagnostics performed using the DHARMa framework indicated satisfactory model adequacy, while zero-inflated models did not substantially improve model performance. The findings suggest that habitat-mediated exposure, particularly sediment-associated pathways, may exert stronger influence on MP ingestion than feeding behavior alone. Overall, this study highlights the importance of combining ecological trait analysis with robust statistical modeling approaches to understand MP uptake dynamics in Mediterranean fish communities.