Sargassum in Isla Mujeres

There is an invasion of Sargassum algae on the Carribean beaches, which started in 2011 and shows no signs of abating. The phenomenon is known as Sargassum inundation, and has an environmental impact on sea life which get caught into the masses of algae. It is also a major annoyance for tourists all over the Carribean. The reason is thought to be man-made, a combination of warmer waters and an influx of sewage and fertilizer carried by the Amazon river into the ocean. A recent article about this phenomenon is here .

Sargassum has a venerable history. It was first observed and described by Columbus on his voyage to the Americas. It used to be localized to Sargasso Sea, an area of the Atlantic Ocean delimited by currents but with no actual shores. A second patch appeared off the coast of Brazil and this is thought to be one of the sources of the recent invasion.

In mid-January spent a week on vacation in Isla Mujeres, just off the coast of Yucatan Peninsula from Cancun, and had a closer look at this phenomenon. It may be a seasonal thing, but in mid-January the Sargassum was just a modest presence on the beach. The local Q Roo newspaper "Por esto!" noted that the amount was not something to worry about.

I found an in-depth study of the species of Sargassum here . This distinguishes between two species: S. fluitans (two forms) and S. natans (four main forms). The inundation is attributed to S. natans VIII (one of the four forms of the latter).

Jeffrey Schell kindly provided detailed identifications of the algae in the images as a mix of S. fluitans III (dominant) with smaller admixtures of S. natans I and VIII.

Posted on January 27, 2019 08:34 PM by danp2