NOAA’s National Centers for Coastal Ocean Science (NCCOS) scientists are examining the presence of pollutants and trace metals within Sargassum – a brown macroalgae – found along Florida’s southeastern coast, Puerto Rico’s southwest and southeast coasts (Culebra), St. Thomas, and St. Croix.
In recent years, Sargassum inundation events have become more frequent and are a nuisance along the coast. Massive amounts of this macroalgae have been washing up in excess along beaches, causing foul odor, beach closures, and infrastructure damage – inevitably impacting the blue economy. These obvious issues pose incredible inconveniences, but little was known about the chemical contaminants present within Sargassum.
NCCOS scientists, in collaboration with local partners, collected Sargassum samples from about 30 sites for analysis. NCCOS scientists at NOAA’s Hollings Marine Laboratory in Charleston, South Carolina analyzed all samples for a suite of trace metals (silver, aluminum, arsenic, barium, beryllium, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, nickel, lead, antimony, selenium, tin, titanium, and zinc), and a suite of legacy organic contaminants (dichlorodiphenyltrichloroethanes [DDT], Polycyclic aromatic hydrocarbons [PAH], Polybrominated diphenyl ethers [PBDE], polychlorinated biphenyls [PCB], and various pesticides).
Chemical analyses showed that a subset of persistent organic pollutants and trace metals were present in Sargassum samples, with PCBs detected most frequently among organic contaminants. Sites with the highest number of detected organic compounds also showed the highest concentrations of inorganic elements. Major elements such as aluminum and iron were most abundant, while mercury and several other trace metals were present at low concentrations.
NCCOS will continue to work with local partners to collect samples and evaluate contaminant patterns across the Caribbean Basin’s coastal and offshore locations. These findings will be integrated with complementary regional Sargassum research efforts, and provided to coastal managers as they develop procedures for Sargassum removal. Learn more about this project and ongoing efforts.
Partners in this effort: University of Puerto Rico, Jobos Bay National Estuarine Research Reserve, U.S. Virgin Islands Bioimpact (St. Thomas and St. Croix), Florida Department of Environmental Protection, and Nova Southeastern University.
NOAA is authorized to advance the scientific understanding and assess harmful algal bloom events through the Harmful Algal Bloom and Hypoxia Research and Control Act (33 U.S.C. §§ 4001 et seq.).