Metal assessment and cellular accumulation dynamics in the green macroalga Ulva lactuca

Abstract

We have tested Ulva lactuca Linnaeus as a metal biomonitor by measuring the concentrations of metals copper (Cu), cadmium (Cd), zinc (Zn), and mercury (Hg) in its biomass and in nearby sediments, within impacted and non-impacted sites in central Chile. Moreover, through Cu exposure laboratory experiments, we observed the dynamics of intracellular and extracellular Cu accumulation in two populations of U. lactuca. Highest metal levels in U. lactuca were associated with human activities; the exception was Cd, with high levels in the control site, although this could be explained due to the important nearby upwelling conditions. Laboratory experiments showed that more of the 90% of the total Cu in the two populations of U. lactuca was accumulated intracellularly, without intra-specific differences. Biomonitoring with U. lactuca provides a positive representation of metal status, which is reinforced in combination with metal measurements in sediments. Weak patterns in metal exclusion suggest the use of different strategies to counteract metal excess in U. lactuca, for instance, associated with the syntheses of metal chelators and the antioxidant metabolism.