You may well be asking – “So, what in the world is Sargassum, and what possibly could be the problem?”
Sargassum is a genus of brown macroalgae (might commonly be called seaweed) that can float at sea owing to the presence of berry-like, gas-filled bladders that provide buoyancy (Photos 1 & 2). Numerous species of Sargassum are present in the tropical and sub-tropical oceans of the world.
In the western North Atlantic, the so-called “Sargasso Sea,” located south of Bermuda and east of Florida and the Bahamas, takes its name from the large masses of floating Sargassum that occur there. This was an ocean area that early western European navigators tried to avoid for fear of having their sailing ships becoming entangled in the floating masses.
Sargassum is not new to San Pedro beaches. What is new is the hugely increased volume of Sargassum that is washing up daily on Belizean beaches and elsewhere in the Caribbean. Reports of increased Sargassum throughout the Caribbean date back to 2011, with the primary source traced to South Atlantic waters off northeast Brazil and the mouth of the Amazon River. That’s a long and tortuous ride to Belize, but satellite images confirm this. Causes for the “Sargassum explosion” are not fully known and understood, but increased nutrient loading in coastal waters and warming ocean waters likely are contributing factors. You can check online for more information about the bigger picture – there are plenty of recent posts!
The big problem along coastlines like that of Ambergris Caye is that the Sargassumwashes into the very shallow waters of the beach zone and then gets stuck there (Photo #3). The Sargassum bakes in the shallow water, dies, and settles to be bottom, where the sheer mass of the algae smothers the underlying, naturally occurring beds of turtle grass that are so important to the nearshore ecosystem. Even worse, the decaying mass sucks up all available oxygen in the shallow water column, resulting in very nasty water and fish kills.
Significant fish kills were reported earlier this spring at several locations along the ocean-side coast of Ambergris Caye. The Coral Ed team has noted that the numbers of fish around the docks of Amigos del Mar (our long-time dive operators) are low, and the large sting rays that all enjoyed watching in the past now are MIA! As stated earlier, the Sargassum also is a real problem for beachfront hotels and restaurants plus for San Pedro city government officials in terms of the costs of Sargassum removal and disposal (photos 4 & 5) and “what to do next.”
“Tropical Paradise” is very much an overused phrase for resort islands like Ambergris Caye. The citizens of “La Isla Bonita” face many challenges, both economic and environmental. Some issues are within direct control of the city council and environmental managers, including over-development, traffic control, trash removal, and over-fishing. Others, such as the threat of hurricanes, deteriorating coral reef health, and the “Sargassum crisis,” are global issues beyond direct local control. How both island residents and the global community address these challenges are open questions, with answers to be determined in the future. In any case, my guess is that no local city council or island-planning group could have seen the “Sargassum crisis” coming…
By Al Curran