Ecological patterns of trace and essential metal bioaccumulation in marine fish from the Gulf of California, Mexico

This study evaluated trace and essential metal concentrations (As, Ag, Co, Cr, Li, Mn, Ni, Se, Sn, U and V) in marine fishes, representing distinct feeding guilds (Balistes polylepis, Stegastes rectifraenum and Kyphosus vaigiensis) from La Paz (LAP) and Santa Rosalía (STR), Mexico, to describe bioaccumulation patterns and assess environmental and ecological variability. Arsenic showed the highest concentrations, with marked interspecific variability that may be related to differences in feeding ecology and metabolic capacity, although its toxicity is likely reduced due to the predominance of organic forms. Essential metals (Co, Cr, Mn, Ni) generally remained within natural background range, while Mn peaks in STR were associated with seasonal runoff. Selenium exhibited high bioaccumulation (BSAF > 14), reflecting its strong affinity for muscle tissue and suggesting high environmental availability, with potential implications for trophic transfer. Elements like Li, V, and U occurred at low concentrations, with U showing patterns consistent with biodilution across species. Spatial differences suggest that metal distributions are primarily influenced by natural factors, including regional lithology and species ecology, although higher metal pollution index values in STR indicate the influence of historical mining activities. Both location and species identity were significant predictors of metal variability and suggest potential inter-metal associations. Overall, the results highlight the importance of integrating ecological, geochemical, and physiological factors in interpreting metal dynamics in marine ecosystems.