Factors affecting arsenic and mercury accumulation in fish from the Colombian Caribbean: A multifactorial approach using machine learning.

In marine ecosystems, arsenic (As) and total mercury (T-Hg) represent two of the major pollutants, particularly in fish due to their ecology and the affinity of these metal(loid)s with biological cycles. This study assessed the influence of total length, total weight, relative condition factor, and trophic levels of ten marine fish species from the Colombian Caribbean on As and T-Hg accumulation in muscle tissue, as well as the differentiation in accumulated amounts based on fish habitat type. In this context, Balistes capriscus exhibited the highest As median (7949.08 μg/kg), along with Thunnus atlanticus (1567.15 μg/kg), Haemulon flavolineatum (1469.26 μg/kg), and Euthynnus alletteratus (1191.55 μg/kg), exceeding the maximum permissible limit of 1000 μg/kg for human consumption. Evaluated factors displayed complex and non-linear influences on As accumulation: trophic level > total length > relative condition factor > total weight, where all factors except total weight described a negative effect. Conversely, for T-Hg, influences were markedly linear and monotonic: trophic level > total length > total weight > relative condition factor, with all factors exerting a positive effect. The habitat plays a crucial role in the cumulative patterns of As, with demersal fish significantly differing from pelagic and reef-associated species. Results indicate that the accumulation of As and T-Hg in muscle tissue may be mediated by a multiplicity of factors inherent to the species' morpho-physiology and the chemical activity of each pollutant in the ecosystem, along with the feeding ecology and niche occupied by these organisms.