In the current scenario of global change, heavy metal pollution is of major concern because of its associated toxic effects and the persistence of these pollutants in the environment. A new study is the first to evaluate the changes in heavy metal concentrations worldwide in brown algae over the last 90 years (>15,700 data across the globe reported from 1933 to 2020).
The study findings revealed significant decreases in the concentrations of Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb and Zn of around 60–84% (ca. 2% annual) in brown algae tissues. The decreases were consistent across the different families considered (Dictyotaceae, Fucaceae, Laminariaceae, Sargassaceae and others), and began between 1970 and 1990. In addition, strong relationships were detected between these trends and pH, SST, and heat content.
Although the observed metal declines could be partially explained by these strong correlations, or by adaptations in the algae, other evidence suggests an actual reduction in metal concentrations in oceans because of the implementation of environmental policies.
In any case, this study shows a reduction in metal concentrations in brown algae over the last 50 years, which is important in and of itself as brown algae form the basis of many marine food webs and are therefore potential distributors of pollutants.
Credit: Aboal J. R., Pacín C., García-Seoane R., Varela Z., González A. G. & Fernández J. A., 2023. Global decrease in heavy metal concentrations in brown algae in the last 90 years. Journal of Hazardous Materials 445: 130511. doi: 10.1016/j.jhazmat.2022.130511. Article (subscription required).
Information provided by: Ocean Acidification International Coordination
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