Abstract

Mercury (Hg) is a toxic metal that biomagnifies through food webs, posing ecological and human health risks. The anchovy (Engraulis ringens), a key forage fish in the Humboldt Current System, sustains major fisheries and transfers energy to top predators. However, spatial patterns of Hg accumulation in this species along the Chilean coast remain poorly understood. We quantified total mercury (THg) in 179 adult anchovies collected along the Chilean coast between 18 degrees - 39 degrees S and evaluated biological (length, mass, trophic position) and environmental (latitude, coastal proximity) drivers using generalized additive models. THg ranged from 7.7 to 56 mu g/kg dry mass (mean 26 +/- 9 mu g/kg). The final model, which included latitude and trophic position, explained 39.5% of the variance in THg concentrations. Latitude was the dominant predictor, while trophic position had only a minor, non-significant effect. Two spatial hotspots of elevated THg were detected near 21-24 degrees S and 33-36 degrees S, likely linked to industrial emissions and regional oceanography. These results indicate that spatial environmental gradients, rather than diet, govern THg variability in anchovy. This baseline information is essential for ecological risk assessments and supports spatially targeted strategies to mitigate marine pollution, particularly in industrialized coastal zones.