Trace Element Concentrations in Macroalgae from a Coastal Lagoon in the Southeastern Gulf of California, Mexico

Macroalgae are valuable bioindicators of water quality because they can bioaccumulate trace elements (TEs) at high concentrations and respond sensitively to changes in environmental TE levels. Here, we quantified Zn, Cu, As, Cd, Hg, Se, and Pb in several macroalgal species from Navachiste lagoon (Gulf of California, Mexico). Overall, TE concentrations followed the order Zn > Cu > As > Cd > Hg, whereas Se and Pb were below the limit of detection. Among the elements analyzed, Hg was the only TE that differed significantly among macroalgal species (p < 0.05), with lower concentrations in Ulva lactuca than in Gracilaria parvispora and Sargassum sinicola. Because G. parvispora was collected year-round, it was used for seasonal comparisons; TE concentrations did not differ between rainy and dry seasons (p > 0.05). These results support the use of G. parvispora as a bioindicator of current TE contamination in Navachiste lagoon, Mexico.