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They discover that the “green tide” of Algarrobo would be composed of at least five species of algae

May 14, 2024

An interdisciplinary group from the Milenio SECOS Institute and the Andrés Bello University, achieved, for the first time in Chile and the South Pacific, the morphological and molecular characterization of the species that make up the so-called “green tide” in Algarrobo, a proliferation of macroalgae that affects to the commune throughout the year. Although the causes are still being investigated, some of the species could have high biotechnological potential, as an alternative use and exploitation of the enormous biomass available.


For almost two decades, Algarrobo Bay has been affected by an excessive proliferation of algae called “green tide”, a phenomenon that has been increasing and whose causes are still being investigated. Throughout the year, sections of the bay that were previously clean sand are covered with a thick, smelly mantle of algae of the Ulva genus. When they decompose, they deteriorate the sector and negatively impact the community, affecting tourism, artisanal fishing and the ecosystem itself.

The problem is of such magnitude that the municipality has been forced to remove the biomass with heavy machinery, which in turn generates additional impacts on the beach. ​ In this context, a group of researchers from the Millennium Institute in Coastal Socio-Ecology (SECOS), the Andrés Bello University (UNAB) and other scientific centers in the country, have been investigating this phenomenon for more than two years in order to identify the species of algae and explain why this proliferation occurs.

Recently, they published their findings in the journal Plants, reporting the first characterization of green tides in Chile and the South Pacific, a publication led by Loretto Contreras, academic at the Department of Ecology and Biodiversity of the Andrés Bello University and researcher at SECOS and the CAPES Center. ​ “The importance of algae characterization may have different foci, but for the Algarrobo area it shows that green tides are multispecies, that is, it is an assembly of several algae that are complex to identify and evaluate at an ecological level, as well as their real impact. in the environment,” says Contreras.

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