Trace metals pollution and trophic position of three sea urchin species in the Gulf of California.

Sea urchin species are ecologically important in the Gulf of California and are becoming popular as a local fishery due to their commercial value. The most abundant species are Echinometra vanbrunti, Eucidaris thouarsii, and Tripneustes depressus. The objective of this study was to evaluate cadmium, lead, copper, zinc, and iron concentrations, as well as stable isotope values in these sea urchin species in the Santa Rosalia mining area (STR), in three sites: Punta Gorda, Punta el Aterrizaje, and Punta Salina. The highest Fe concentration (100.2 mg kg^-1) was found in E. vanbrunti, while the highest concentrations of Pb (15.1 mg kg^-1), Cu (14.5 mg kg^-1), and Zn (347.7 mg kg^-1) were recorded in E. thouarsii, and the highest Cd concentration (10.8 mg kg^-1) was found in T. depressus. The main health risk of trace metal pollution in STR may be caused by Cd and Pb. δ¹⁵N and δ¹³C values were higher in E. thouarsii and T. depressus, respectively; E. thouarsii has the highest trophic position. Specimen size was not related to metal concentrations, but a positive relationship was observed between specimen size and isotopic values in T. depressus. The three species showed different bioaccumulation patterns for the metals analyzed. Additionally, collection sites and seasons play an important role in the variability of metal concentration.